In the California Bay Area where we work, we see a great number of improperly built retaining walls. In this article, we’ll talk about what retaining walls are, why they often fail, and how to make sure you hire someone who is doing the job right. Let’s jump right in …
What Exactly Is A Retaining Wall?
For the purposes of our work, a good definition of a retaining wall is a structure made of wood, concrete, brick, block, etc. whose function is to retain soil or other materials where the height of those materials is greater on one side than on the other.
Retaining walls are often installed to hold up soil outside of the building adjacent to patios or in sloped areas of the yard, or they are used for foundations where the interior grade is lower than the outside level such (in excavated basements, for example).
When the height of the material (generally soil) that is higher on one side causes uneven forces on the wall, then the wall is subject to either overturning or sliding. A retaining wall is designed to resist those forces, usually with the use of an L-shaped footing (for concrete walls) with a base approximately 1/3 to ½ the height of the wall to prevent overturning, and a notch (or keyway) at the end of the footing extending farther down to prevent sliding. These walls are heavily reinforced with rebar to give them greater strength.
Here’s an example of a foundation retaining wall in a basement prior to a concrete pour showing the footing, the keyway, and the rebar:
Here’s similar retaining wall in the rear yard of a home:
This type of retaining wall works well when the area on the downhill side of the wall is level, e.g. when there is a patio below, or a basement under the house.
When there is a slope on both sides of the wall or the soil on the downhill side is in poor condition, we will often drill piers (usually to a depth around twice the height of the wall, depending on the soil conditions) and install steel I-beams set in concrete to perform a similar function. By drilling deep into stable soil, this type of wall will resist sliding and overturning as well (see below).
Why Most Retaining Walls Fail
Most concrete retaining walls that are in your yard fail due to three reasons:
Lack of drainage
Older walls, especially those around 4’ or less in height, were built as “gravity walls”, which means they had little if any footings and were designed to stay up based upon their mass and weight. This will often be sufficient for many years, but eventually they start to lean and at some point fail due to movement of soil behind them–often related to lack of drainage. This is an example of a typical leaning gravity retaining wall. All the trees and vegetation behind the wall did not help matters, as roots and their expansion helped push this wall down over time.
All vegetation was removed and we rebuilt the wall with a French drain behind it to relieve future water pressure from behind the wall. That drainage pipe was brought under the sidewalk and out to the street, as you can see in the picture where there is new concrete at the sidewalk and the curb. The rebar extended in the footing for the wall (below the dirt in the space between the sidewalk and the wall). We added a stucco texture coat to the concrete for low maintenance and to create a finish similar to the stucco on the house.
Wood Retaining Walls
The picture below shows what typically happens when wood retaining walls fail:
More than likely these posts are shallow (often 2’ deep rather than the suggested 4-6’ deep average) and not able to withstand soil movement. Since the wood posts are set in dirt, they will often rot at the ground level due to exposure to moisture, and this will occasionally occur in a relatively short time (5-10 years) if they go with new growth redwood which is not very resistant.
Wood posts should be set in concrete above the ground level so they are not exposed to a lot of water. These walls often lack drainage as well. They depend on water to weep out between the wallboards. Sometimes they have drainage holes that clog. Installation of a drainage mat or a proper French Drain will ensure more effective drainage over the long term.
Here’s another before and after of a properly constructed wood wall (that we built), with deep posts set in concrete and proper drainage:
This wall had drilled piers about 15’ down. Walls built with shallow piers are done primarily to save money and avoid drilling, but they do not fare well over time.
Bottom Line About Building Retaining Walls in California
Most concrete retaining walls in Bay Area CA where we work fail due to inadequate footings, lack of drainage, and a lack of reinforcement. For wood walls with posts, it’s generally shallow piers, lack of drainage, and the lack of pressure-treated wood members. Modern properly engineered walls are more expensive, but are more economical in the long term since they should last a lifetime rather than requiring frequent reconstruction if they are done improperly.
I moved to the Bay Area in 1978 to go to school at Cal.
The weather back in those days was very different. Summers were foggy days until the afternoon when the sun popped out. The fog went away in the Fall and we had Indian Summers and that was usually our hottest weather. Winter started in October and lasted until March or April with off and on rain with mild temperatures.
Since then the weather has been a lot more erratic (most likely due to climate change, say experts).
Less fog, warmer weather in general, and periods of drought interspersed with periods of extended rainfall. And anyone who lives near the Bay Area in California knows that when it does rain, it rains a lot. Sometimes and inch or two in an hour, or more. The normal yearly cycles are extended out so that we can have several years of dry weather before getting substantial rainfall.
The question is …
How is this affecting your home?
Most of our local soils consist of a lot of clay below the topsoil. This clay will expand and contract seasonally, causing doors to stick and then not stick, cracks to appear and disappear around doors and windows, most of which were seasonal and fairly limited.
Because the wet and dry cycles are becoming more dramatic, their effects on your home are increasing.
The primary issue is the lack of drainage in most of our older homes–both downspout drainage and sub drains (French Drains), combined with the age of our foundations systems. Intermittent rain in reasonable amounts will often not cause issues, but in larger quantities we are seeing settlement which can be more dramatic, leading to more interior cracks, larger cracks, more water in basements and crawlspaces, and more deterioration and failure in older foundations.
Since most homeowners do not monitor the areas under their homes, these issues do not come to their attention until they see cracks or water inside the living spaces.
And homeowners are seeing a lot more of this.
When the issue is primarily surface water, the problems may pop up right away, seemingly out of nowhere, during rain events. The subterranean water issues will often increase as the rainy season goes on and the soil becomes saturated and the water table rises.
Earlier this year during a particularly rainy month, I received about 50 calls in one day regarding basements that had flooded where homeowners had lived there for 30 years or more with no water in their basements.
So what can you do about it?
The answer is nothing new other than what I have been preaching all along–there just is an increased urgency based upon the changes in weather.
Old foundations need to be repaired or replaced so that you have proper reinforced concrete of appropriate dimensions that is in good condition so that your building will be properly supported and settlement will be minimized.
And proper drainage needs to be correctly installed so that water will not affect the foundations and lead to settlement.
Once this work is completed your home should weather the storm and give you peace of mind down the road.
If you live in our service area of Oakland, Berkeley, Piedmont, or Alameda and are having foundation or drainage issues, fill out our estimate form and we’ll come out and take a look for you and help you make sure you get the job done right the first time.
If there’s one thing I’ve learned in my nearly 40 years as a structural contractor, it’s that lack of preparation and research is the #1 reason homeowners end up getting burned on foundation projects like basement digouts.
In this article, I’ll tell you about some common pitfalls to avoid when choosing a Bay Area basement digout contractor.
Let’s jump right in …
There are couple of paths you can follow when you are digging out under your house to create new living space:
1. Hire a Contractor for the Whole Project
One approach is to hire a contractor for the entire project. This includes the structural and remodel work from start to finish.
The advantage of this is to have a more seamless job with all of the details being considered in the design and execution of the work.
This could be done either with a design-build company that handles everything, or hiring an architect to do the design and having contractors bid the work with a general handling all of the construction.
This tends to be a more expensive solution for homeowners, as most general constructors subcontract out this work.
2. Hire a Foundation/Structural Specialist for the Basement Digout
The alternative is to hire a foundation or structural contractor to do the dig-out and relevant structural work, and then to bid out the remodeling separately.
Why would you want to do this? For several reasons:
You save money (as much as $50,000-100,000 on larger jobs) by getting more competitive pricing on the remodel work, with clients generally acting as their own contractors and hiring subs, carpenters, etc. to deal with the more detailed parts of the project.
You have more personal control over the design and work or to spread it over a longer period of time to keep the budget under control.
If You Decide on Option #2, Here’s What You Need to Know
It’s important to consider the relationship between the initial project and the future remodel, both in terms of what needs to be considered in the initial job that will affect the remodel, and how these projects are viewed by the various building departments and the pitfalls to avoid moving forward.
It would probably be easiest to illustrate this using an example of a project we are currently working on in Oakland …
The owner had an existing basement with an average ceiling height of around 6.5’ that was being used mostly as storage, but which she wants to convert to living space in the near future. She has a plan of how she wants everything laid out: adding a couple of bedrooms, 2 baths, family room, laundry, and garage, and has hired us to do the structural.
We had our engineer draw basic plans for new foundations, drainage and slabs with a new ceiling height of 8’. In our plans we show this space remaining as unfinished basement.
The City of Oakland does not allow you to create new finished space, including things like bathrooms and bedrooms, kitchens etc. (some of which may not be legally allowed due to zoning regulations) without proper permitting. Generally, they will allow you to add storage, office space, utility areas, etc., if these spaces are already partially finished but the ceiling height is increasing, but in our case we just showed it as unfinished basement before and after.
The primary things we had to consider were the locations of future doors and windows and locations of plumbing that would go under the slab (i.e., drain line for bathrooms).
In this project we had the rear door shifting over (affecting the foundation), and we had to install sleeves in the foundation in the areas of the planned bathrooms for drain lines to be done during the remodel. Since we had a basic design of where things were going to be, we were able to determine that we had sufficient height in the locations of the bedrooms for future egress windows required by code.
The new central foundation was done below the slab level to allow for a central wall where we could add future openings wherever we saw fit rather than having to decide now on their exact locations. Instead of adding seismic upgrades now as part of the structural work, that was deferred to the remodel, since insulation, electrical, etc. would be behind any plywood sheer walls that would go in and would require their removal later.
Our experience with complete basement remodels and related permitting issues and how they vary from one city to another allows us to anticipate in advance issue that might come up later in the remodel, or might cause the dig out plan to get rejected by the City up front and complicated and future remodeling plans.
In Summary: How to Choose the Right Bay Area Structural Contractor for You
A well-organized project with the structural and remodel that are separated, can easily save a client $50,000-100,000 on a larger basement job if they want to manage their own remodel project.
But it is crucial that elements are not left out of the structural work that would cause problems later on, or require demo or redo of structural work, particularly if under slab plumbing issues are not considered early on.
And making sure proper drainage is done as part of the work is critical. Some structural designs leave in the current foundations and excavate in front of them to add additional foundation. In this scenario drainage is often ignored … until it causes major problems in the newly finished space in the next wet winter!
One of the most frequent questions we get at Jim Gardner Construction is some variation of the following:
Why are there cracks in my house? Why are my floors not level? What should I do about it?
In this post we’ll break down typical causes and solutions for interior and exterior cracks so you can make an informed decision about how to take care of these issues the right way.
Common Causes of Cracks in Your Home
Cracks on the interior and exterior of your home, and floors out of level, are generally a symptom of structural issues down below. Since most people spend very little if any time in their crawlspaces, they are not seeing what are often some fairly obvious deficiencies that are causing these problems.
The root cause of the problem most often occurs with drainage issues (this is especially true in our service area of Oakland, Berkeley, Piedmont, and Alameda CA).
Inadequate surface and subterranean drainage systems cause water to travel under your foundations, and with older concrete with no rebar, they can develop cracks and shift or settle. At the exterior walls, this often occurs adjacent to downspouts that are not connected to any underground piping and are allowed to drain freely next to your house (not good).
When this happens, water can spread throughout the crawlspace, or when you are on a slope water will often pop up in the crawlspace after moving under the foundations and will cause dampness, mold and settlement in certain areas. Settlement can also occur at interior piers that are often shallow, or affect retaining walls on the downhill side of the crawlspace, causing moisture issues in finished or unfinished basements.
Foundations will generally settle at the outside perimeter due to poor drainage, and this can cause floors to sink, sloping towards the outside. Sloping at points in the interior is generally caused by interior pier or central foundation settlement, and can sometimes be exaggerated by structural inadequacies created by work done in the crawlspace (generally framing that has been removed or modified to accommodate plumbing or heating ducts that has caused weaknesses at those locations).
Cracks on the interior usually occur around doors and windows, or at openings in walls that have a lot of weight being supported above them and are poorly supported below. These cracks often occur at the corners of these openings at the headers above doors and windows where the weight is concentrated.
How to Fix Cracks in Your Home
Proper drainage is key to preventing additional movement. If French drains and downspout drainage are inadequate or non-existent they should be installed ASAP. If the foundations are damaged or are in poor condition, they should be repaired or replaced. Improper framing should be repaired. Interior piers should be installed that are of proper dimensions to provide adequate support for the loads above.
Once these corrections are made, any future settlement related problems should be minimal. Leveling can then be completed, though this is often not a simple process. The stucco has to be cut at the exterior and the floor lifted, and sometimes damage will occur to the interior or exterior in the areas being leveled, in relation to the degree of lifting required.
If the floor slope is substantial this may be a priority, but we minor sloping (generally figured at less than an inch per 10’) sometimes you can get away with leaving it alone.
This is more of a cosmetic than a structural concern, so your tolerance for the unevenness has to be weighed against the complexity and cost of the leveling work.
Sometimes it makes more sense to level the floors on the inside by adding various thicknesses of plywood and patching material and installing new flooring. This is easier in scenarios where floors are already scheduled for an upgrade.
Long story short, leveling, drainage and foundation and structural repairs should generally be done first before any substantial interior cosmetic work is done.
Clients often have recurrent cracking on the interior that occurs seasonally and is difficult to deal with because it comes and goes. Once the drainage and structure are fixed then cracks will be much less likely to recur and interior cosmetic repairs should no longer need to be redone … saving you a lot of money in the long-run.
If you live in the Oakland, Berkeley, Piedmont, or Alameda area and would like a quote on getting your home’s cracks fixed once and for all, contact us for a quote.
If you own an older home in the Bay Area, your front porch porch should be a big area of concern.
Here’s why …
Porches can look okay from our normal vantage point (up above) and not appear to be in distress.
However, when viewed from below (in other words, from a structural perspective), we find that many are close to failing.
Given the health and safety ramifications of a porch that’s in bad shape, it makes sense to figure out if there are any issues during any visit to the crawlspace and to come up with a plan of action for any needed repairs.
In this article, we’ll tell you what to look out for and how to choose a contractor that does the job right the first time.
If Your Front Porch Is Falling Apart, This Is Probably Why
As is the case with drainage and foundation issues, water is usually the primary culprit in porch deterioration and failure.
The waterproofing between the framing and concrete was only tar paper back in the day, with a limited life span. And since concrete becomes somewhat porous over time, along with minor cracks and voids in the concrete and stucco that allow water in, moisture can cause the tar paper to deteriorate, leading to damage to the framing and sheathing underneath.
Since old framing was typically redwood, there’s limited moisture resistance, which leads to dry-rot. Damaged framing can then lead to settlement of the unreinforced concrete slab and steps above, leading to cracks, and then causing further moisture infiltration and ongoing damage.
The extent of damage will often determine the suggested solution to the problem. If the structural damage is minor and the concrete above is still in reasonable condition, we can sometimes get away with adding additional pressure-treated (AKA moisture-resistant) framing under the porch landing and stairs to stabilize things and prevent further movement. If the concrete is badly cracked, with no remaining waterproofing and significant framing damage, there becomes a point where total replacement is warranted.
How to (Properly) Replace a Front Porch That’s Failing
In a replacement scenario, there are many complex steps involved (most contractors will skip one or more of these):
We remove all of the old concrete, waterproofing and framing. If the porch foundation is deteriorated, settled badly and is in poor condition it should be replaced as well.
We install new upgraded pressure-treated framing, generally a lot beefier than what was there originally.
We then install pressure-treated plywood sheathing, and on top of that we install a bituthene waterproof membrane, a major improvement over the prior tar paper.
Metal flashing is installed where the porch meets the house and where the stairs meet the sidewalls, prior to new lath and stucco repairs.
Rebar is added to the new concrete for additional strength and stability.
Current code dictates that any areas on the stairs or landings with drop-offs of 30 inches or more requires 42-inch guardrails with maximum 4” spacing between members. This is generally achieved with metal railings or reconstructed stucco sidewalls, but this can be a design challenge given the fact that the original guardrails were often non-existent and stucco walls were often very low.
Fortunately, we have several solutions to meet current code that are aesthetically pleasing.
The combination of new foundations, new pressure-treated framing, waterproofing and reinforced concrete and upgraded railings will provide the proper safety and longevity to the porch and stairs that was previously lacking.
If you’re a homeowner in Oakland, Berkeley, Piedmont, or Alameda and you need your front porch repaired or replaced, fill out our estimate request form and we’ll get back to you right away if we feel we’re the right fit for you job!
One of the most common questions we get from customers is:
What do foundation and drainage projects cost?
If you need foundation repair or drainage work done and you live in the Bay Area, chances are you’ve gotten prices that are all over the map.
And the truth is, the costs of doing foundation and drainage work can be really confusing. As is the case with a lot of structural projects, the confusion often stems from a lack of a well-defined scope of work.
In this article, we’re going to share something our competitors in our service are of Oakland, Berkeley, Piedmont, and Alameda wouldn’t dare put in print: cost ranges for foundation and drainage jobs!
We’ll also share some insider tips for making sure you choose a contractor that doesn’t turn your dream house into a nightmare.
Let’s get started …
How Most Foundation and Drainage Repair and Replacement Jobs Start
Most foundation and drainage projects start as a result of a report created during the home purchase or after, or signs of damage or concerns either in the crawlspace (if it is easily viewed) or cracks, sloping floors, or other issues in and around the home that seem to be a sign for concern.
The actual cause of these problems usually requires a detailed crawl in the often tight, poorly accessible areas under you home- places that are often not carefully explored. During our estimates we try to look thoroughly in all the key areas under your house, since what you notice above is generally a reflection of what is happening under your house.
From the structural perspective, the most common reports generated during a house sale are often poor or incomplete types of information. A few examples …
The Home Inspection Report is highly detailed but very general.
The Termite Report has solutions that are primarily to alleviate termite and dry-rot problems which are often poor structural solutions.
It is rare to get a good Engineering Report on a building (because it can be expensive), and even then it is often technical and confusing. And there is very little if any good pricing associated with these.
So you know you have a problem, but you’re not exactly sure what it is or what it costs. Next, you go contractor hunting …
How Most Homeowners Choose a Contractor
Due to the fact that very few contractors are structural specialists, and most contractors doing drainage/foundation work tend to be inexperienced, you usually end up dealing with generalists who do not have a good handle on the nature of your problem.
That’s not good.
And it’s even worse with drainage, because most drainage contractors lack the knowledge and experience to handle more complex drainage jobs. Then you layer on top of that the guys who are trying to sell you the version of the job they are most comfortable with (not the one that’s the best solution for you) and you end up on the “Contractor Ferris Wheel” with the ride stuck in mid-air … and eventually going downhill from there.
There is a better way though–a smarter method for those of you who want your foundation to last and your house to stay dry.
Let’s look into foundations and drainage separately in more detail so you can better understand what we’re talking about …
How do you even know if you need a new foundation?
It’s a basic question, but surprisingly there’s not a simple answer.
We evaluate foundations mostly on visual inspection and minor probing of their condition–the number of cracks, the relative size and depth of the footings, grade issues, but most importantly the relative strength of the materials.
Unbeknownst to many, the real enemy for foundations is water (as it is for most construction materials).
Concrete is somewhat porous, and over many years older concrete will degrade if subject to a lot of moisture because of drainage related water. 10-20% (or so) of the older foundations we look at have concrete that is so poor you can pull chunks of it out with your hand. Clearly not a good sign if the plan is for the foundation to support your big heavy, home.
And given the fact that most wet foundations last around 100 years in our service area and most of the homes were built between 1910 and 1930, and that they have little if any rebar in them, many foundations need replacement.
I grade them on a scale of 1-10. 1-2 means “you better replace it ASAP”, but beyond that it becomes more of a judgment call. 3-5 is more of a question of longevity–if you plan on living in the home for a long time, we usually recommend replacing the foundation and installing proper drainage. If a prospective customer wants get the heck out of Dodge and pass this problem on to the next person, then oftentimes they’ll pass on a big, expensive project (but this usually comes back to bite them when they try and sell the house).
Ok, now that we have that out of the way let’s talk costs …
Foundation repair and replacement costs in the Bay Area are primarily driven by the lineal footage of the foundations, but also by things such as access, exterior items next to the foundation that need to be removed and replaced to do the work (such as patios or stairs), and most importantly by the height of the foundations.
Access to the site can also be an issue. If it is up on a hill 50 steps from the street the work can be much more difficult, resulting in more labor hours and a higher estimate. If you have basement walls vs a crawlspace, the height of the foundations will be another cost driver. A 6’ wall will cost 3x or so what a 2’ foundation on a level lot will cost.
In real dollars, a simple foundation replacement for a small house in the flats will typically be $30,000 – 40,000, where a larger house in the hills with a developed basement and large foundation retaining walls could be as much as $200,000.
As most genealogists would tell you, “it’s all relative”. But you should be aware of these factors when considering the prices you are being given for this work. And your contractor should be able to give you a sense of how these costs are derived. If he/she can’t, that’s a big red flag.
To generalize, a large percentage of foundation projects we do fall into the $40,000 – $60,000 range, but again there are a lot of factors.
Next, let’s talk drainage …
The type of drainage, its depth and location are key issues driving drainage cost. Due to the substantial presence of groundwater and the need for French Drains as well of downspout drainage, I have a tendency to recommend both elements as a part of most of my drainage quotes (unless there is an obvious surface only water problem).
From experience we have learned that partial systems often fail due to water re-routing itself over time (that’s a whole different discussion), or inadequate depth of the work or improper waterproofing and poor detailing of the membrane system and piping.
French drains need to be installed below the lowest floor elevations of where the water is getting in to provide a safe long-term solution. Depending upon whether this drainage is around the entire house, or in the crawlspace and around the house, it can vary from 3’ to occasionally 10’-12’ deep in extreme cases (see our gallery at the bottom of this page for some examples).
With deeper drainage work we are required to do shoring and other OSHA approved methods for providing safety in deep trenches. This requires specialized equipment, such as aluminum trench shoring, and specialized training. Not all contractors have this in place, putting their employees and you the client at risk.
And as with foundations, drainage project costs are determined by depth, access, exterior elements that need to be removed and replaced, etc. What often gets missed, but plays a big role in whether or not to do this work, is the current condition of the foundation.
If the foundation is in fair condition or better, and if it could get a 20-40-year reprieve on its lifespan with good drainage rather than needing to replace in it a much nearer term without drainage, than the cost of good drainage is a great investment.
So how much do drainage projects cost?
As a general range, houses of small to mid-size with short crawlspaces and mostly dirt around them average around $35,000 for complete drainage systems. Houses with full basements and stairs and patios that need to be removed and repaired can run up to $80,000, with drainage 8’ deep all around.
As is the case with foundations, jobs on hillsides can be substantially more time-consuming, leading to additional cost. Most drainage systems are hand-dug, since they need to be placed adjacent to the house foundations so that waterproofing can be effective. Small electric jackhammers are the tools of choice, but the work is labor-intensive, usually requires a large crew, and involves removing huge amounts of soil (30-50 tons of soil removed is not unusual in a drainage project).
But as with foundations, whoever is bidding the work should be able to explain how the cost is generated.
Sometimes the amount of items surrounding the perimeter of the building can be substantial, with removal and replacement costing as much as the drainage work itself. In the 80K example above, we needed to replace a substantial brick over concrete staircase and landing, which is 15K of that project cost, along with portions of the rear patio.
If the contractor knows what they are doing and is honest, there should be a reasonable explanation as to how the pricing is arrived at that should make sense to you as a homeowner. If a contractor isn’t able to help you understand why a project costs what it does and explain what they’re going to do for your (large) investment in your home, then it’s time to look elsewhere.
At the risk of sounding like a crazy contractor, I want you to know one very important fact:
I don’t care if I get your job.
What I do care about is working with homeowners who are willing to do what it takes to implement a long-term solution to foundation and drainage issues.
I don’t want to come back and fix your job 5 years from now because it didn’t last.
This is particularly true with drainage, because drainage patterns change and partial solutions often prove to be ineffective over time as water will re-route itself as ground conditions change and will lead to other water issues where they weren’t previously.
With drainage and foundation work though, choose your contractor wisely. Ask questions. Talk to other clients of theirs who had similar issues. And most importantly, make sure they’ve done this type of work before (a lot of it).
If you have a foundation/drainage project and you live in Berkeley, Oakland, Piedmont, or Alameda, fill out our Estimate Request form and let’s see if we’re the right fit for your job.
If you are getting a lot of different answers and getting confused as to what to do, it is generally because the contractors don’t know the answers and are guessing. Most structural repairs are done by General Contractors without substantial experience or knowledge in this area. 90% of the jobs I look at generally have one way to do them right.
Most clients have no knowledge about their foundation and its condition until they begin to notice problems inside their homes- generally settlement cracks, sticking doors and sloping floors are indicators that something is amiss.
Though there is no cut and dry formula to show when a foundation needs to be replaced, there are a number of indicators which when looked at together should point the direction one way or another.
1. Are there drainage issues?
Drainage is the #1 culprit, and leads to settlement, cracking, and deterioration of concrete. Older concrete is somewhat porous, and water will soak into the material causing it to deteriorate. Since most older homes have nonexistent or improperly installed drainage systems, it is important to have the drainage issues addressed- either as part of the foundation work, or if the foundation is in decent condition to avoid an expensive foundation replacement project in the short term.
2. Is the concrete deteriorating?
By poking around with a screwdriver, we can see how intact the concrete is. Often concrete with lots of sand in the mix that has been subjected to drainage issues will be so soft it can be pulled apart with your fingers. This condition can be of major concern, as this concrete has very little strength and could liquefy in an earthquake. The harder the material the better. Appearances can be deceiving. Some of the ugliest concrete with lots of rocks and voids can be quite strong and is less of a concern.
3. Are there cracks?
A few cracks in older foundations is expected, but lots of cracks, especially one’s that are ¼” or larger can be problematic. Since older foundations typically do not have rebar in them, once large cracks occur the concrete can separate into sections that can rotate or settle independently from one another, causing settlement or shifting in the house above.
4. Is there rebar?
Most homes built before 1930 or so do not have steel reinforcement in them. Rebar helps to strengthen the concrete and hold it together in the event of cracking from settlement or earthquakes- cracks can still develop, but they remain hairline and don’t pull apart. The modern foundations we build have at least 5 pieces of rebar running horizontally, and verticals every 12” so they are heavily reinforced.
5. Depth and location of the concrete.
Often older foundations are not of sufficient dimensions to work effectively. If the footings are not at least a foot or more below the grade level they will be subject more to movement in expansive soils and drainage issues. If they are not 6” or more above grade there can be water issues at the framing level causing dry rot issues above. And if the soil is excavated on the interior of the basement or crawlspace too close to the foundations or if the footings are functioning as retaining walls and they are not designed properly they may settle or move, and they may create drainage issues leading to more settlement.
6. How old is the concrete?
Concrete from the early 1900’s that is still in place in older foundations is often in poor condition. Since most of the homes we work on in the East Bay were built between 1900 and 1930 this would definitely apply to them. Again, drainage, lack of rebar, improper dimensions, cracks etc. are much more pronounced in older foundations.
When all of these elements are looked at together, it is easier to get a sense of how your foundation is performing in these key areas. In many situations, where I give the foundation an overall score of 1-3 on a scale of 1-10 the need to replace is fairly obvious. In the 4-5 area it often becomes a more difficult question, where the client needs to consider their resources, how long they plan on remaining in the home, etc. If the foundation is in fair condition but in need of drainage work which might add another 20-30 years to its lifespan, that is often a reasonable alternative course of work. When the condition is poor, however, it generally does not make sense to do a drainage only project, since that work would need to be torn out and redone sooner rather than later as part of an inevitable foundation replacement.
The bottom line is that water is the main culprit implicated in most of the damage created to the exterior of your home, and can lead to interior damage as well. Maintenance problems such as chipping paint and damaged trim, poor flashing details around windows, decks, porches and doors, a roof which is leaking or needs replacement, or the lack of a proper drainage system around the home will all lead to potential problems when water comes into contact with your residence. Rainfall and underground water sources such as creeks and springs, a high water table, irrigation systems, leaking water lines or broken or disconnected drain lines- all of these water sources can wreck havoc on your home. Lets discuss how the different components of your homes exterior are affected.
Many of the older homes in our area have foundations that are in poor condition.
But this is not merely a function of the age of the concrete. Since most of the foundations were installed without drainage systems moisture in the ground adjacent to them, whether from rainwater or subterranean water sources, is causing them to deteriorate. Concrete becomes porous over time, and the water will saturate the interior of the concrete and cause it to break down. Water in the soil adjacent to and under the foundation, in conjunction with the expansive clay soils present on most of our properties, will cause the foundation to move as the soil shrinks and expands between wet and dry periods. Since older concrete is generally unreinforced it can settle unevenly causing it to crack, allowing more water to enter causing settlement. This often appears as cracks in walls, ceilings, and around doors and windows, along with sloping floors. Installing proper drainage will help alleviate these types of problems.
In older homes the stucco was often brought all the way to the ground. Since there are boards behind the stucco that were in contact with the soil, this gives termites access from the ground. When the paint and caulking are not maintained water can get in around doors and windows, leading to dryrot. Poor flashing details around porches, decks and roofs and leaking gutters and downspouts can allow water into the building as well, and termites love warm moist spaces. Foundations should always be at least 6”-8” above the soil level to prevent termites from entering at the base of the exterior walls. Foundations that are in poor condition should be replaced with taller, steel-reinforced footings. For foundations in better shape, concrete termite curbs can be installed at the outside of the building to create this clearance, and they are a more reasonable alternative to replacement. Painting and caulking should be properly maintained and trim should be repaired or replaced if damaged. Gutters and downspouts should be repaired if they are leaking, and they should be properly sloped to drain properly, flashed and kept clean to make sure they don’t leak into the exterior walls.
When your foundations move for the reasons described above, this can lead to cracking and settlement on the interior walls and ceilings, doors and windows that stick or won’t close, etc. Sloping floors reflect foundation settlement or damage. By correcting the moisture problems first the interior damage should be minimized, at which point it will be appropriate to undertake repairs.
In summary, water is often the main factor leading to a large variety of structural repairs. Soil problems, earthquakes, and poor construction- these can also cause damage, but they are less common. Water is a subtle culprit that affects many older homes over an extended time frame, increasing with the age of the homes foundation. The sooner the maintenance issues can be corrected, the less they will affect the structure as a whole and the lower the ultimate cost of repairs will be.
We were recently doing some minor repairs to a set of front concrete stairs when they suddenly and inexplicably collapsed into a pile of rubble in front of the home. After overcoming my initial dismay, I began to consider what might have caused this dramatic event. If this were to have happened when the homeowner was entering the house they could have been seriously injured. From above and below the stairs appeared to be in reasonable condition.
On closer inspection it was clear the concrete steps had been patched in the past, allowing water to get into the support framing. The only waterproofing under the old concrete protecting the framing was building paper (tar paper), which has a limited lifespan when it is in frequent contact with moisture. Since the old concrete had no steel reinforcing (rebar), once it settled due to the poor support framing it actually broke up into several smaller pieces. The wood form material underneath the stairs concealed this cracking. Because of a lack of proper flashing where the steps met the stucco sidewalls, water got into the walls and rotted the studs. This framing made up the structure supporting the steps, but it was also concealed by the stucco. All it took was the removal of one 2×4 and the whole thing came crashing down. If you figure at least a couple of cubic yards of material you are looking at approximately 10,000 pounds of concrete!!!!
Front stair and landing replacements are becoming a significant part of our work, and with good reason. This dramatic collapse shows what can happen when the damage is severe, and why it might go unnoticed. With older concrete structures that show signs distress one should make test openings in the stucco and the support framing to look closely at their condition. If they are in poor shape it might make sense to consider replacing the whole structure. Sometimes new foundation work is required, but not necessarily. We would demo the existing concrete steps and support framing and replace the wood with new pressure-treated material, usually of a bigger dimension and with narrower spacing. This usually requires some detailing from our structural engineer to design the supports to modern engineering standards. On top of the framing we use pressure-treated plywood and then a bituthene roofing membrane for waterproofing, along with metal flashing at the sides adjacent to the wall framing. The final step is the steel-reinforcing for the new concrete. The end product is a much more supportive structure which will provide a safe entrance to your home for many more years to come.
Why A Watered Down Solution Can Do You More Harm Than Good
Having spent a lot of time in recent years reconstructing a number of ill-conceived drainage projects, it has become fairly obvious that there is a serious lack of knowledge on the part of both the installers and homeowners as to the ABC’s of a good drainage system. Unfortunately, putting in a poorly designed (and often inexpensive) system can create problems that weren’t there to begin with, leading to extensive repairs down the road.
One of my best examples came several years ago on a project we did in Oakland. The homeowner came to me complaining of settlement problems in their new kitchen. Tiles were cracking, and the floor and cabinets were out of level. This was on the main floor. At the basement level there was a large crack running the length of the house in the slab floor, about 4′ in from the outside wall. Obviously there were some settlement problems, but what had caused them?
After discussing the problem with my client, I learned that several years prior they had installed a drainage system (at the cost of around $3,500) that was level and around 2′ deep, with a slight slope towards the front of the house. It was obvious to me that this water had nowhere to go, and it was sinking into the ground adjacent to the house causing it to settle. What should have been installed was a system starting at the front corner of the house, below the level of the adjacent basement floor, starting at about 4′ deep and terminating in the rear yard in a drain-field at a depth of about 6′. This system would have cost them around $10,000.
Did they end up saving any money? Not after the $50,000 they had to spend to replace the damaged (brick) foundation, structural and framing repairs, new drainage system, stucco repairs, kitchen repairs, slab repairs, etc. (see the picture below). The contractor was long gone, and they were out of pocket a lot of money.
So what are some of the key points we need to know to avoid these types of problems in the future?
Don’t mix up your sources of water. In the Bay Area we need to consider both surface water and subterranean water as possible problems. The surface water (from your downspouts or patio drains) is transmitted through solid drainpipes to either a drain field or to the street (depending on your City regulations and site conditions), and the underground water is collected in perforated pipes by a deeper system commonly known as a French Drain. These pipes need to be kept separate in the system and not co-mingled. Inexperienced drainage installers sometimes dump the surface water into the French drain, which places excessive water into the trench that sometimes creates a bigger problem under your home.
Water runs downhill. It may sound rather simple, but the drainage system needs to be sloped correctly to its termination point. A general rule of thumb is 1/ 4″ per foot minimum for the downspout drainage, and 1/8″ per foot for the French drain. This often means that on a big system the end of the drainage is a foot or more below the starting point, and the trench needs to be sloped accordingly. On level lots this often requires sump pumps to be installed due to a lack of slope.
Place your drainage adjacent to your foundation where possible. When you can use an excavator to do the work, it may make sense to place the drainage away from the building if there is a substantial cost savings (versus a labor- intensive hand-dug system). Since most of our systems are hand-dug due to limited access, we like to put them up against the foundation for a couple of reasons. First, if the drainage is away from the building there is an increased possibility that some surface water will still get between the new drainage system and the building and go under the house. Second, by trenching next to the house we can attach a waterproofing membrane to the foundation that will protect the foundation from continued exposure to moisture. This may extend the life span of an older foundation. As long as you are careful not to undermine the foundation during excavation, digging next to the foundation should not be a problem.
Your French Drain should be deeper than the level of your problem. Subterranean water from creeks, springs, and other sources can run very deep, and sometimes runs year-round. If the drainage system that is built on the uphill side of a basement or crawlspace is not constructed to a depth below the level where water is getting in you cannot be sure that your problem is solved. In fact, it can sometimes make things worse if the trench now collects larger volumes of water that may enter the building. This principal is often violated because deep drains are substantially more expensive than shallow ones. Sometimes the drainage can be 6′ to 8′ down, or even deeper in certain instances.
Watch where you dig. Water always wants to seek a lower level, and it will find its way into your sub-area through any opening or penetration you create for it. I see a lot of situations where site drainage created as part of a landscaping project will create shallow trenches in the yard that bring water adjacent to the foundation, creating drainage problems in the basement or crawlspace that are new.
Make sure your drainage design plan is sound before embarking on any new drainage project. By paying attention to certain basic drainage principles and by doing the job right you will avoid a lot of problems in the future.