21 Jan December 2020 – Without a Good Foundation, Trouble is Lurking
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December 2020
Number 82
We at Willis Sinclair hope you had a very nice
Thanksgiving.
We also wish you the very best
Christmas and New Year
possible.
From the Desk of Willis
Hello everyone! We hope you and your families are all healthy and well. No doubt this has been a very trying year for many in having to deal with all of the dynamics of the virus.
We are truly blessed that all of my immediate family has managed to stay healthy so far. We are also very fortunate to have been able to maintain steady work for all of our usual workers this year. No one knows what the future may hold but we remain optimistic that things will be back to “normal” or even better than normal very soon.
Speaking of “normal” what does that even mean? Normal to most people would be what they are accustomed to doing or having happen on a daily basis. While most people view “normal” as nice (because it’s predictable), we need to make sure we don’t get stuck there and refuse to change for the better. We also have to be careful of those who want to institute a “new normal” that may not be good for us or very much to our liking. Everyone’s “normal” will be a little different and part of what makes America so great is our freedom to decide what is normal for us and not have a “normal” imposed on us.
I often consider the appropriate use of certain words like “normal”, “exceptional”, “marvelous”, “incredible”, “amazing”, “remarkable”, etc. Most people think of those words in a positive light to describe something that is good. Interestingly, all of those words (except “normal”) could be used to describe this year 2020. It truly was exceptional (was unlike any previous year), marvelous (we can only marvel at how it unfolded), incredible (too extraordinary to be believed), amazing (we wonder how it could have happened), and remarkable (worthy of being noticed). I dare say we Americans have taken notice and hopefully will all make positive changes in order to prevent another such year. If that were to happen then we could actually look back on the year 2020 as a really good year that helped us grow better and stronger.
This month we are discussing the importance of good foundations. While our newsletter is focused on homes, a lot of the same principles apply to people and their lives. I believe that in order to have a meaningful and productive life you have to have a good foundation to build upon. The stronger your foundation the more you are able to build on it. I was given a good, strong foundation by my parents and have worked hard to strengthen it for my children. My hope and expectation is that my children will be able to quickly achieve and then surpass my accomplishments in life. For me the future looks bright and exciting, no matter what’s going on in the world around us, because I believe that many people, who were raised on good foundations, will be taking an increasingly active role in the future of America!
Foundations
| He is like a man building a house, who dug deep and laid a foundation on the rock; and when a flood occurred, the torrent burst against that house and could not shake it, because it had been well built. But the one who has … not acted accordingly, is like a man who built a house on the ground without any foundation; and the torrent burst against it and immediately it collapsed, and the ruin of that house was great. — From an ancient text. |
Foundations are one of the most important parts of your home. Once the home is constructed, important parts of the foundation cannot be seen, so it is critical to follow the construction (or have a dependable builder). There are several building department inspections during this phase, but the inspectors are human and cannot catch everything. Nor can they insure changes are not made after the inspection.
There are several functions the foundation serves. It supports the home, it provides an anchor for the home, it provides a platform for the home to be built upon and in many cases, it protects items under the home (wiring, plumbing and HVAC equipment) from damage due to rodents.
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There are little (and not so little) creatures out there that would love to nibble on your wires. That is not a good thing. A solid foundation wall and rat slab will hinder these critters. A rat slab is a two or three inch thick slab of concrete poured in the crawlspace to keep animals from burrowing under the footer to gain access to the crawlspace. |
As the introduction text states, it is good to build on bedrock, but here in the Lowcountry where bedrock is very deep, that is not practical. (There are places we have put down 60 foot long pilings and not hit bedrock.) Since bedrock is out of reach, the next best solution is to use a large footer to distribute the weight of your home over a large area. This keeps the pressure on the soil to a minimum. (This same principle is why very heavy (60 ton or 120,000 pound) army tanks use tracks and not wheels. The tracks distribute the weight over a very large area and thus reduce the pressure on the ground.)
Not only are the footers large, the soil where the footers are to be poured is also tested (a soil compaction test is done by an independent, licensed engineering firm) to confirm the soil is compact (solid) enough to support the home.
The foundation stem wall (top gray box) is supported by the footer (horizontal box above yellow). The footer is typically 2 feet wide here in the Lowcountry. The soil compaction test verifies the soil beneath the footer will be sufficient to support the home.  |
It is fairly common for homes to have various piers beneath them to support long spans. One issue that sometimes arises is the pier which is poured on its own footer can shift or lean. This leads to problems such as cracked drywall, sagging floors, sticking doors and other problems caused by poor support. The solution to this problem (which we always do) is to connect all of the footers so there is one footer under every wall and pier. This makes the likelyhood of a pier shifting virtually zero. If we are not building your home, make sure your builder pours a continuous footer.
 It is fairly common for homes to have various piers beneath them to support long spans. One issue that sometimes arises is the pier which is poured on its own footer can shift or lean. This leads to problems such as cracked drywall, sagging floors, sticking doors and other problems caused by poor support. The solution to this problem (which we always do) is to connect all of the footers so there is one footer under every wall and pier. This makes the likelihood of a pier shifting virtually zero. If we are not building your home, make sure your builder pours a continuous footer. |
The stem wall is typically CMU (concrete blocks) laid on the footer up to what will be the bottom of the floor system of your home. The blocks are then filled with concrete and a solid beam of concrete poured around the perimeter of the home. Since the frost level here in the Lowcountry is very low — probably less than an inch — stem walls don’t have to go very far below the surface at the lowest point.
Some stem walls are filled with compacted dirt and then have a slab of concrete poured over the fill dirt as well as to the outside edge of the stem wall. This construction is called a raised slab because the slab is raised above the surrounding ground level. If the stem wall area is not filled, but remains open, a crawlspace results beneath the flooring system. Code typically says this height needs to be at least 24″ so workers can move around under the home.
The advantage of a raised slab is the cost and typically the time to build. The floor is solid which sometimes is not too pleasant to walk on. Sometimes, a sleeper system (flooring on plywood subfloor supported by 2x4s — sleepers) is added above a solid concrete floor to somewhat soften the floor. The big downside of the raised slab is that all of the plumbing drain lines must be under the slab. Other utilities may also be beneath the slab, but with plumbing drain lines, there is little option. Mechanical items below the slab are fine unless something fails. If a leak does develop and you discover it, you need a jackhammer to get to the source.
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A raised slab will be poured over the fill dirt inside this stem wall. The plumbing drain lines have not been buried yet, so none are visible. The steel rebar (from the footer) will be bent over and embedded in the slab to solidly tie the slab to the foundation.
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A crawlspace allows easy access to the utilities (unless they are buried in insulation). With a crawlspace you can either insulate the floor or seal and insulate the perimeter. Sealing the crawlspace typically costs about the same as insulating the floor and leaves the wiring and plumbing exposed in a protected environment.
If you look at foundations (or other concrete structures), you will see steel bars or mesh where the concrete is to be poured. The steel is to reinforce the concrete. The bars (called rebar and sized in eighth inches — #4 rebar is 4/8″ or 1/2 inch in diameter) provide much of the strength. Typically there are two or three running around the footer. Rebar is also placed in the footer and routed up through the stem wall to the concrete cap which is poured around the top of the stem wall.
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This is the crawlspace beneath a home we built. It has a rat slab. The height is about 32″ (4 concrete blocks each 8″ high). There are some piers visible on the left side. |
Why use steel if concrete is so strong? Steel is used because concrete is strong in compression only. It is difficult to crush concrete. Under tension (pulling), concrete is not very strong (about 10% of its compression strength). Steel, on the other hand, is very strong under tension. A #4 rebar will hold about 11,500 pounds. Three (typically in a footer), would then have a tensile strength of 34,500 pounds.
At the top of the stem wall, J bolts are embedded in the concrete. Their purpose is to provide an attachment point for hurricane tie downs. Since the tie downs reach up to the top plate of the home, the foundation serves as a solid anchor for the home. Just how solid? It is not uncommon for a foundation system to have 100 cubic yards of concrete. Each yard weighs about 4,000 pounds, so a foundation made of 100 cubic yards of concrete weighs about 400,000 pounds (not counting the concrete blocks and steel). The concrete is also embedded in the ground, so the hold down force is significantly greater than just the weight of the concrete. In most storms even if the house is blown away the foundation will remain.
Foundations might not seem as important as interior finishes, but they are definitely critical to your home’s integrity. We expend a lot of effort on the things you don’t see in your house (foundations, framing, etc.) so that you can enjoy the things that you do see, problem free, for a long time. When hiring a builder it’s important that you hire one who cares as much about the longevity of your home as the appearance. Call us for any of your home needs, we care.
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