Foundation Watering

Foundation Watering : In some areas of the country, including parts of Texas, there is a lot of expansive clay in the soil.

Many people assume that concrete is a very rigid substance, and relatively speaking it is strong, but concrete will bend. If you could pick up the slab of concrete that your home is sitting on, and support it only from the middle, you would see the edges of the concrete sagging or hanging down several inches lower than the middle where it is being held up. This “experiment” would show that concrete indeed does flex. It is the flexibility of concrete that causes cracks in the interior walls and in the brick walls on your home. It also causes doors to stick or not latch, and windows to stick. If your concrete slab flexes too much, it can even crack.

The expanding and shrinking of the expansive clay soil under your home is what causes the foundation to flex. Expansive clay soils can exert as much as 5500 pounds per square foot of pressure on your home’s foundation. Since the moisture level in the soil changes most significantly around the edges of the home, it is around the edge where most of the pressure will be exerted as the soil goes from dry to wet. Then during a dry spell, as the soil begins to dry out, the soil will contract. This will then cause the edges of the foundation to sag as they have little support underneath. Over time, this cycling of the soil from dry to wet and from wet to dry, and the resulting flexing of the foundation, can damage your home.

This settling can cause wall cracks, doors to not operate properly, and some unlevelness in the floors. These issues are mostly just cosmetic and annoyances. But, if the movement is significant and is allowed to continue, then this flexing of the concrete can cause some real damage such as cracks in the foundation and broken piping. In order to protect your home, it is essential to protect the foundation and minimize the movement/flexing that it is forced to undergo. The most critical factor in accomplishing this is to minimize the moisture changes in the soil around your home. Foundation watering is the simplest method that has been developed to achieve this.

How to Water Your Home’s Foundation

Watering your home’s foundation may sound like an odd thing, but if done consistently and correctly, it is probably the single most important thing that you can do to protect your home’s foundation. It is critical to minimize the wet and dry cycles to which the soil around your home is subjected. Since it is impossible to keep the soil around your home dry, then it is important to keep it wet –  and you can accomplish this by watering the soil around your home’s foundation.

The term “foundation watering program” is actually a misnomer because you do not want to water the foundation. You want to water the soil next to your home’s foundation. In fact, it is critical that you do not allow water to pool against your home’s foundation as this can cause more problems. On many homes with expansive clay soils, there is a gap between the soil and the concrete foundation during dry seasons. When you set up your watering system, it is imperative that you don’t allow large amounts of water to go down into this gap as this will cause additional damage to your foundation.

Here are the basics of a foundation watering system. You set up soaker hoses about 12 – 18 inches from the perimeter of your home, and run water regularly through these to keep the soil damp around the home. This always-damp soil will be more stable and will minimize any expansion and contraction of the soil and thus minimize the extreme forces to which your home’s foundation will be subjected.

How to Set up a Foundation Watering System

To set up a watering program, you will need to set up soaker hoses all the way around your home (excluding concrete areas such as sidewalks and driveways). You can hire someone to do this for you and it will likely cost $2000 – $3000, or you can do it yourself for about $300. Here are the steps to take to set up your foundation watering system.

1. Determine how much soaker hose you will need. Take into account the flatwork (concrete areas) that will not need soaker hose. You can go over or under concrete using regular water hose or pvc pipe. You can purchase a tool that will help you to easily tunnel under the concrete and run pvc pipe. (You don’t need to water under sidewalks or driveways because concrete does a pretty good job of keeping water from evaporating from the soil underneath the concrete.)
2. Decide if you will use one or more hose bibs (outside water faucets) for your foundation watering. Take into account the concrete that you will have to go under or around and decide the most efficient route to take. You may want to use hose bibs in both the front and back yards and possibly go both directions from each hose bib as this may allow you to avoid the concrete altogether.
3. Purchase the following items: (All prices and photos are from The Home Depot)
   1. Enough soaker hose to go around the home
   2. PVC pipe and fittings for the concrete areas.
   3. A “Y” or splitter (a metal one should last longer than plastic) for each hose bib that you are going to use. The splitter will allow you to still use your hose bib for other purposes since the soaker hose system will be connected year-round. (About $10)
   4. An electronic watering timer for each hose bib that you are going to use. This will allow the system to water the foundation automatically without you having to think about it. (About $40)
   5. A hose thread pressure regulator for each hose bib that you are going to use. Most public water systems supply water at pressures ranging from about 50 – 100 psi. If you use water at a high pressure with your soaker hoses, then most of the water will be dispersed into the soil in the first few feet of the soaker hose and the remainder of the soil will not be watered at all. Lowering the water pressure to 20 – 25 psi will ensure a much more uniform distribution of the water. ($5 – $10 each) 
   6. An anti-siphon device for each hose bib (about $28). 
   7. Yard Staples. These will be used to hold the soaker hose in place if you choose not to bury it. (About $12) 
4. Decide whether you want to bury the soaker hose or leave it on the surface. Here are the pros and cons to leaving it on the surface:

Pros- 

• The system is much easier to setup because you don’t have to trench around the entire home.

Cons-

• About 10% of the water will evaporate rather than soaking into the soil.
• The hose does not stay in place as well as when a trench is used.
• The hose is more susceptible to damage such as from a mower.

If you are going to leave the hose on the surface then you will use yard staples to hold it in place. If you decide to bury it then you will need to dig a trench about 4” – 8” deep and 12” – 18” away from your home’s foundation.

5. Place an anti-siphon device on each hose bib that you plan to use. Thread a timer onto the anti-siphon device, then thread the pressure reducer onto the timer. Set the pressure on the reducer to 20 – 25 psi.

6. Next, thread the soaker hose onto the pressure reducer and begin laying it either into the trench or along the ground 12 – 18 inches from the foundation using the yard staples to hold it in place. IMPORTANT NOTE: There is a flow restrictor in the female end of the soaker hose. This is a plastic disk with a small hole in it. You MUST remove this restrictor from each hose before installing it. If it is not removed, you will not get proper flow through the hoses.

7. Depending on how you are running your hose, you will either terminate the soaker hose when you come to concrete or you will transition to regular water hose or to PVC. If you are terminating and are near the end of your hose, then you can simply put a cap on the hose. If you have a lot of hose leftover, then you can cut off the hose to the desired length and fold it over and clamp it, or you can insert a threaded fitting that you can screw a cap onto. If you are going to transition to regular hose or to PVC, I recommend that you ask someone at your local hardware store for advice on the proper fittings that you will need. IMPORTANT NOTE: When you have to make a corner with the hose, make sure that you do not kink it as this will restrict flow. Either make a slow rounded corner or cut your hose and add a 90-degree fitting.

8. Once you have all of your hoses run, and before you cover your trench, turn on the water and let it run for about 10 minutes. Then check along the hose to make sure that there are no leaks. Also, check and make sure that you are getting water along the entire length of each of the hoses. Check especially at the end of each run to see that you are getting water all the way to the end of each hose. If you don’t have water flowing out somewhere along the hose, then you will need to figure out the cause and correct it. Perhaps there a leak or blockage somewhere.

9. Once you are satisfied that there are no leaks, and that there is even water flow all along the hose, then you can cover the trench if you dug one. When covering the trench, do not pack the dirt so tightly that you risk squeezing the hose closed or partially closed since this would obviously restrict water flow.

10. Now, you are ready to set up the timer(s). How often should you run your soaker hoses? You obviously need more water during hot, dry weather than you do during the cooler months. Small amounts of water several times per day is better than a longer watering time once per day. I would suggest that you set the timers to run water for about 15 minutes twice a day, between about April and September. You can run it about half as much in October, part of November, and March. You may not need to run it at all from November to February. Running the hoses early in the morning or late at night will minimize evaporation. So, set your timers and forget about it – for a while.

11. How do you know if you are underwatering or overwatering your foundation? After about a month, go out and dig a hole about 2-feet deep in a couple of areas near the foundation. Take a handful of soil and try to make a ball out of it. If it is similar to playdough and holds its shape well, then it is just right. If it just crumbles apart, then the soil is not getting enough water. If the soil is actually wet and you can see and feel the water, then it is too wet. Make adjustments as necessary and leave it alone for another month or so and then check it again.  If may take two or three times to get it set just right, but once you do, you won’t have to keep digging these test holes.

Once you have set up your foundation watering system, you will likely not see any immediate changes. It may take up to six months before you will begin to see the changes that your foundation watering system are making to your home. Eventually, you should see some cracks closing up and some doors and windows that operate better. You should also see the cracks in the soil, and the gaps between the soil and foundation starting to close up.

Once you have the system operating, all you should have to do is to change the amount of watering as the seasons change. I would recommend that you check the dampness of the soil every three or four months. An easy way to do this is to use a long screwdriver. In several areas around the home, stick the screwdriver into the ground as deep as possible. If it goes easily into the ground and comes out basically clean, then the soil wetness is just about right. If you cannot push the screwdriver into the soil without a lot of effort, then the soil is too dry. If the screwdriver comes out wet, then the soil is getting too much water. Make the appropriate adjustments, and check again in a couple of months.

Your home’s foundation is its most important system, because without a good foundation, you do not or will not have a home for long, so you must protect the foundation. Setting up a foundation watering system is a do-it-yourself project that can be completed in a weekend, and a system that is properly set up and maintained will help to protect your home’s foundation for many years. If your home is built on a slab-on-grade foundation, and the soil is expansive clay, then this is one of the most important DIY projects that you can undertake. It will help to preserve your home’s foundation and its value for years to come. If you have any questions about foundations or how to water your foundation, please leave a comment or reach out to me. 

© 2020 Mike Morgan

This article was written by Mike Morgan, the owner of Morgan Inspection Services. Morgan Inspection Services has been providing home, septic and well inspection services throughout the central Texas area since 2002. He can be reached at 325-998-4663 or at mike@morganinspectionservices.com. No article, or portion thereof, may be reproduced or copied without prior written consent of Mike Morgan.