How much water does it take to crack a foundation wall?

Answer 1

All houses do, even ones which have been newly built. What becomes difficult for most homeowners to see is the movement happening because of the weight of the house sagging down, or is it because of the foundation. I have written about inspecting a house for homeowners and investors, so I do not wish to go over that again; however, on several recent inspections, I found that I was repeating myself when it came to some repair items concerning foundations, mainly slab on grade foundations with post tension cables. I thought it might help to have one post collecting all of my recent comments to buyers to provide some guidance on how you may want to take care of your own foundation.

Want your foundation to stay in one place, then look up. On a home inspection two days ago, I came across one of the biggest problems for a foundation, and it was at the roof line, the gutter system. The gutter was filled with pine needles. Two story homes always seem to have gutters that never have been cleaned. Pine needles are the worst. In most of Houston, we have a clay soil that will expand when wet, and contract when dry. Correctly installed and functioning gutters will divert the rain water away from the home, so you do not have water ponding. Water ponding is where pools of water stay around the base of your home. A clean water will take the water to the downspout. The gutter has to be installed in such a way that water will flow to the downspout pipe on its own. Over time, a gutters support system can be weakened, and the water will pool in one spot. To see if this is happening to you, take a hose to run water through your gutters. If it does pool, then find a way to have the gutter lifted at that spot, so water will flow naturally. The next problem area on my inspection reports is typically how the downspouts discharge their water. In the photo, you can see that the pipe runs along the foundation into the ground. Downspouts should cause the water to flow away from the foundation. No downspout should ever run along the foundation. There should always be a splashguard or tube perpendicular to the house. Tip for working on gutters: when setting up your ladder, find a support bracket for the gutter (sometimes these are just pins into the fascia). Straddle your ladder over this bracket to minimize damage to the gutter by the weight being applied to it. Fasten the ladder with bungee cords to prevent it from slipping away.

Can you see your foundation? Most homeowners do not like the look of an exposed foundation, so they put garden beds or yard up to that level to cover it. Exposing your foundation has some benefits that having nothing to do with foundation maintenance. Termites do not like crawling up open areas. High ground level allows water to flow into the house through the exterior wall. These raise beds also keep water right by your foundation. Creating a drainage system along your walls, and exposing the foundation can help stop water from ponding there. The drainage system could be one of those perforated tubes running along the wall. Often this is called a "French Drain", but a French drain is actually a drainage system below ground at the base of your foundation. Another drainage method is having the landscape graded to allow water to flow away from the house. "How can I hide my foundation then?" Good question. When planning out garden beds, incorporate the drainage system, and leave part of the foundation showing. Six inches of foundation should be visible for brick or cement exteriors, and eight inches for wood. Then find plants that will cover this area of the foundation. Keep the plants spaced where at the full growth, they will be a foot away from the wall. This allows air flow, and it creates an open space that termites do not like. If you do not want a full garden bed, you could plant an ornamental grass in a strip along the base of the home.

We have dealt with water staying around your foundation, but what if it is to dry. When I was a little boy, I thought it was quite strange to see my grandfather "watering the house" after my grandmother had watered the garden. My grandfather went to all of the spots around the house where my grandmother had not watered. I asked home him why, and he reminded me that there was a drought. He did not want any area around the foundation not getting water, when one part was. I have found that this lesson of watering a foundation during times of drought has not been passed onto homeowners anymore. The idea is to prevent the ground from being too wet or too dry. With our frequent droughts in Houston, we have to remember that those trees around the home will be sucking up any available water, which will pull our foundation down. (At the time of this writing, Houston is six inches behind in its annual rainfall, which means the foundation needs watering).

My foundation has been damaged; what can I do? Last year, I saw a builder fix a cracked foundation with Duct Tape. I could not fathom his belief that this was an acceptable fix. Most often, I see items on the foundation which really do not call for a foundation repair, but they do worry my clients. A "corner pop" happens at the corner of the home; it is a crack at the foundation that will look like the corner of the foundation was being knocked off. The weight of the building, predominately the roof, will come down through a corner, causing a small piece of the foundation to crack. For the most part, these pops are not serious. Another crack caused by much the same thing runs along the foundation and a brick exterior wall. This happens because of weight being applied to the butter coat. The "butter coat" is a smooth coat of cement that covers the real foundation. This coat is fairly thin, and I see it being knocked off by people using lawn mowers. Revealing the rough foundation may look bad, but this is not a cause for concern. You can smooth over that patch with mortar mix. This leads me to one patch being knocked off that can cause a problem. You may have noticed these little cement bumps (caps) in your butter coat. Maybe this cap has been knocked off, revealing a cable end. These are the covers for post tension cable ends. These cables stretch through your foundation to improve its function, and they are under a good deal of stress. I would say that on 90% of the homes that I inspect that have this foundation, there will be cement caps missing from these ends. If this end rusts away, the cable can snap, ruining your foundation. I noticed that on homes built since 2006, a plastic cover is placed over these ends to help prevent rusting if the cement is knocked off. To repair this, you will first place an anti oxidant compound on the cable end. You can find a suitable substance at home centers, but I purchase mine at automotive part stores, since I use it when working on my old Beetle. After the compound has dried, you apply a new coat of mortar.

Lastly, some advice about foundation repair. Two situations arose recently where the homes had the foundation repaired, but other problems came about, because of this work. The foundation is being lifted during a repair, and this movement lifts the remainder of the house. This lifting will cause cracks in walls. An inspector should be able to tell the difference between cracks which indicate movement, and those that indicate foundation problems. If you did have your foundation repaired (or you are soon), you may want to prepare your self for some repairs to the walls. Mostly filling in cracks. The other problem that I saw had to do with an addition onto the home. The addition's foundation was separate from the main house, but the walls had been tied together through framing. When the house was lifted, a large crack formed between the house and addition. Since there were no other foundation problems, the crack needed to be filled. This kind of crack will also happen along garage floors of attached garages. An attached garage's floor is typically not part of the foundation; it is a slab, like a porch. Movement in a house happens; it is normal, and you cannot stop it. You can take a few steps to help your foundation out, and that can save you money in the end.