Water is the REAL ENEMY for most homeowners!

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.

The Foundation
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.

Exterior Walls
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.

Interior Damage
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.

All Drainage Systems Are Not Created Equal

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?

  1.  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.
  2.  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.
  3.  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.
  4.  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.
  5.  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.

Solving Residential Drainage Problems

Drainage problems are quite a nuisance for many homeowners in the Bay Area. Flooded basements, garages, and water in crawlspaces and in finished spaces under homes are commonplace. Most people don’t know where to start to solve these problems, or worse yet may have had prior drainage work done that was either inadequate or in some cases actually made their problems worse. A basic understanding of drainage fundamentals may help homeowners make better decisions regarding future drainage work.

Drainage ABC’s

One of the most important things to understand is that there are two types of water that need to be managed- surface water and subterranean water. Surface water is water from roofs, downspouts, patio drains, and water that runs along driveways, walkways, etc. Surface water is primarily rainwater and causes problems during and shortly after it rains. Subterranean water comes from underground creeks and springs, irrigation lines and leaky pipes, or a high water table. Tree roots and fissures in the soil create conduits for water as well. This water is more difficult to manage because it is often not possible to determine its exact source or depth, or in what direction the water is traveling when it encounters your home. It often appears long after a storm and is sometimes present throughout the rainy season or even year-round. Subterranean water is a big problem for many hillside dwellings in our community. This is especially true in older homes where the concrete foundations are porous, shallow or may have some settlement and cracking, allowing for easier water infiltration.

The Correct Solution

To properly solve your drainage problems one must consider both types of water. When we suspect that subterranean water is contributing to a drainage problem, we will often install a subsurface drain (commonly known as a French Drain) in conjunction with our surface drainage. When we install drainage next to a foundation, we will also attach a waterproofing membrane to that wall. This acts as a secondary barrier against water and protects the concrete against further degradation from moisture. The water is then piped to the street under the sidewalk and through the curb either via gravity, or with a sump pump when the house is below the street level. Most building departments prefer that the water is not directed into your yard because it may end up in your neighbor’s yard if it is not properly absorbed into the ground.

Don’t Be Fooled

French Drains are commonly around 3′-5′ deep, but are occasionally much deeper. Substantial amounts of soil have to be removed and replaced with gravel as part of this process. This type of work is not cheap- it is certainly more expensive and involved than surface drainage. Yet it is sometimes the only way (and is often the best way) to keep a crawlspace, garage, or basement space dry while at the same time protecting adjacent foundations from moisture. Improperly designed or shallow drains can sometimes exaggerate the drainage problems and make them worse. It is best to consult with a contractor or engineer who has substantial experience with this type of work before embarking on drainage repairs. A properly designed and constructed drainage system should take care of your water problems and protect your home well into the future.

Written by Jim Gardner of Jim Gardner Construction Inc., a contractor, Piedmont resident, and specialist in residential foundations, drainage, and structural repair