Best Foundation Repair Method Slab

Frequently Asked Questions

1. QUESTION:
   What are the different types of home foundations?
   We are in the process of trying to sell a house that was built in the late 1960s. A potential buyer commented on the way the foundation was built. There is a space of about 1″ between the floor and walls. I was built this way and isn’t a crack. Is this normal? The buyer is complaining about potential water damage. Thanks!

   • ANSWER:
     Well, I’d have to ask for more details first, before commenting on this particular problem. For example… where is the gap? What is the floor made of? Are there any cracks in the foundation?

     During the 1960’s, here in the US, you began to see more and more houses built on concrete slabs. There are 2 ways to approach a slab home. The first is to pour a complete slab, usually 4 to 6 inches thick, and build everything on top of it. With this method, the floor actually runs under the walls, so there should be NO gap, unless you are measuring a gap between the wall covering, and the floor surface.

     The second method, is the way many ‘post and beam’ buildings, such as barns, are put up. Garages are often done this way too. Whether for a home, garage, barn, whatever, if the grade is sloped, or the pour is below grade, then the walls will be poured concrete to at least above the grade level. Once the footers (and if necessary, the walls) are poured, then the slab is poured INSIDE the perimeter of the foundation. A lot of basement floors are done this way too.
     Ive never seen a 1″ gap between a poured floor and perimeter foundation, or poured wall, though, if you mean the floor stops about 1″ away from the wall, horizontally.

     If the gap you are talking about is between the wall covering, and the floor surface (that is, you would measure the 1″ gap by holding a tape measure up and down), then there may have been some settling, or the wall covering was built with that much gap for a reason (maybe they intended to tile it later?)

     One important question… Have you HAD any water damage, or know about any in the past, if you have not owned the home since it was built?

     And, Its still your house, if you don’t want to deal with this individual, tell them to go find another house to buy.

     Your best option is probably to hire a foundation/concrete repair specialist to come in and look at the situation. They can tell you if there has been any settling, and how to correct it. They can also, if necessary, eliminate that gap for you. In the long run, if you really need to sell the home, this is probably your best option. (They can also tell you if your situation is common for your area)

     Your other choice is to give the buyer such a good price, they’ll buy it knowing they’ll have to correct any problems themselves. Be sure, if you choose that option, to get it spelled out very explicitly in a contract.

     I’d say call in that concrete foundation expert… if nothing is wrong, they can put that in writing for you. If there is a problem, they can tell you how to best go about fixing it.

     Good Luck

2. QUESTION:
   choose foundation repair method?
   Texas
   House 16 years old. Owner for less than 2 years. Extensive damage! 2 estimates: 1 for 12 piers (cement), 1 for 32 piers (steel). 500,000 house. Texas clay soil

   • ANSWER:
     It really depends on the size of the slab and the extent of the damage. For smaller jobs, you can get away with mud-jacking. For larger jobs, you might have to resort to piers and piles.

3. QUESTION:
   i need a professional method statement for isolated footing foundation & Slab on grade?

   • ANSWER:
     Designing it, building it, repairing it,, describing it? “For” is too much of a catch all phrase. Perhaps you could spare a few more words.

4. QUESTION:
   Is it foundation trouble?
   I am looking at homes and need to know if this is foundation trouble because I have an FHA loan, and I have heard they are pretty picky about the house. The home I like may have foundation problems. The dirt has come away from the back of the home and the small porch has separated from the back door, but the house itself is still on its slab, unmoved. You can see under the house because of this, and the concrete slab is fine. The home is on a hill and the back yard has retaining walls so it makes me think the backyard is eroding. There are no cracks inside or outside the home. Is it a major problem? I will try to get pictures soon.

   • ANSWER:
     This sounds more like the porch has settled, and not a foundation problem with the home itself. Still you can insist on its being repaired before you purchase the home.

     The most likely repair for this type of settling, would be what is called ‘mudjacking’, or ‘helical pier’ repairs. With the mudjacking, a foundation repair company would pump a cement slurry (a thick mud, made of cement) under the porch, bringing it back up to the level it was originally at. This is also a good method to re-level concrete patios, and floors (such as a garage floor). With a ‘helical pier’ type of repair, the company would literally, dig a small hole, 2 or more feet deep, next to the porch (or foundation, if that was what had settled), and they would install a ‘jack’ that is operated by filling it with cement.

     These types of repair are usually done by the same business, and this is much more common than it was, say 30 years ago. You can easily find a contractor close to your home by searching for “mudjacking”, or using a site like ServiceMagic their link is here – http://www.servicemagic.com/

     Again, this sounds more like a problem with the porch itself, and not the foundation – but a foundation repair company is who you would call to fix it.

     The other option would be to tear off the porch, and rebuild it – if it is a small porch, this might be cheaper than repairing.

     Good Luck

     Oh, just an afterthought here – If you have an FHA loan, then the FHA will send an inspector out to look at the home before you buy it, and they would flag something like this for repairs before they would approve the purchase. If you can see under the foundation of the home itself, then it is likely they would require that to be filled in too.

     Good Luck and Best Wishes

5. QUESTION:
   plumbing test on cracked foundation-followup?
   I’m having trouble finding links on methods of sewer pipe repair. Can they be repaired from inside the pipe or must they be dug out and repaired? This is a floating slab.

   Thanks

   • ANSWER:
     No they must be dug up and repaired

6. QUESTION:
   Do I need to repair foundation?
   I had a foundation repair company come out and they told me I needed to get it fixed because the front of the house was .5 to 1.7 inches dropped in some areas. I do have many hairline cracks on the sheet rock and 2 big ones on the ceiling and one one the wall. My home is 12 years old. The strange thing is he told me if we don’t normally water the foundation consistently it is better to not water at all. (you got me) . I have a feeling all repair companies will say I need to fix it. Is the drop really that significant to have to fix?

   • ANSWER:
     By reducing and defining the amount of settlement from your previous question it would appear that although you have an issue it is not a catastrophe. Since you have big cracks in the wall and ceiling corrective work would appear appropriate. The cracks will not get better without repair work. You may want to follow the suggestions I made previously about how to proceed.
     If your house was a slab-on-grade foundation it would be possible to have a mud jacking company come in and lift the slab back into position and then proceed with the wall and ceiling repairs. But as I remember you noted the foundation contractor had suggested the use of piers to correct the settlement. This would indicate that either you have a cast in place concrete or concrete block perimeter foundation with probably a crawl space under your floor. By jacking up the floor to its proper elevation and installing piers for support the settlement can be corrected. That from what we know from the info provided that would probably be the most economical solution.
     By watering the foundation consistently you would have been trying to take over for mother natures responsibilities in keeping the soil at a consistent moisture content to keep the moisture under your footings at a consistent level. I have no idea how you could do this successfully since you would have to adjust your amount of watering on the weather conditions and the soil moisture content below the footings. The surface moisture content is not indicative of the moisture under the footings in that they are a foot or two under the surface. The moisture at that level is also effected by the ground water level that rises and falls. Don’t try to mess with mother nature you have no idea how much or how little water is needed under the footings.
     It would appear with that much settlement in only one area of your house, that area of your house was built on top of a clay seam that was not isolated by use of a good granular fill which would have minimized any settlement due to clay shrinkage if the clay should dry out more than its condition when the footing was placed. It is understood that when clay drys out it can shrink in volume and its load bearing capacity will actually increase in its new lower position under the footing. So when it drys out the footing will settle and move to a lower position. The footing and support wall will both crack to allow the settlement. Now lets say you add enough water to saturate the clay under the footing. Although the clay will have a tendency to expand, with the footing load on the clay, the path of least resistance for the clay to expand is to the sides and down from the footing. It will not raise the footing. (This is different from the mud jacking method where adequate pressure is applied to the mud jacking material to push to the sides and down with adequate pressure until adequate resistance is achieved that it is easier to lift the footing than to go out the sides or down.) To continue, now you have wetter clay under the footing than is normally there and the water dissipates to the surrounding soil. With the water leaching out the clay drys out. What happens when clay drys? It shrinks and your house’s footing drops again. This is why once you get settlement on a clay soil it will continue to settle unless the problem is corrected, mud jacking or additional support such as a pier / piers on a stable base, not clay. If the clay is down deep enough under the foundations or the piers its poor foundation support qualities are neutralized for all intents and purposes.
     The repair companies will tell you it needs repaired because if all is factual information that you provided the problem will not fix itself and can get worse. If you have the foundation issues fixed, I would wait for at least a couple weeks before I started any interior wall and ceiling repairs until the house stabilizes. It will take a little time, winds rain, temp changes etc. until the house settles into position.

7. QUESTION:
   Structural engineering question?
   First the background: I want to build a house using CEBs, Compressed Earth Blocks. (If you want to know more about the CEBs check out thes link: http://www.adobemachine.com)

   They are considerably heavier than conventional building materials. Each block is 10″wide x 14″long x 4″ thick. They will be stacked with the 10″ side facing out and thus will make a 14″ thick wall course. The exterior walls will be two courses thick with a small chase between them to allow for electrical and plumbing. The interior walls will be one course.

   Each of the blocks weighs about 40 pounds. Stacked as stated above that will create a wall that weighs 14,400 pounds per 10′ x 10′ section for each course and thus a 28,800 pound 10′ x 10′ section for the double course.

   My main question is: what is the formula to determine the thickness of the of footings and slab given the width of the walls and the weight?

   Once the floor plan is finalized and the interior walls laid out and the lengths of the exterior walls determined I want to be able to estimate what the foundation work and materials are going to run me.

   I would also like to build this with a flat top roof (a little slope for rain runoff of course,) and I would like the roof to be make of concrete. How do I do that? Do you pour it in forms in place or do you precast it in sections and then crane it into place? How thick can/should it be (I want it to be tornado proof?) What sort of support is required during construction and afterwards. The interior walls will provide some support but the rooms will be large and I am wondering if I will have to have support beams from the floor up or will I need support beams spanning from wall to wall at the ceiling (I-beams?)

   Also should I use foundation support piers (like the foundation repair guys drive down to bedrock when they repair a broken or cracked foundation?) I was wondering if that would help support something as heavy as this house is going to be.

   • ANSWER:
     These are all great questions! I really do enjoy designing the structures for all kinds of buildings, especially custom residential homes. This seems like it will be a great project by the way you describe it.

     First of all I want to suggest that you have a licensed structural engineer to work along side you during your design process. The questions you have posed here have fairly complex answers and you may not have thought of all the implications of your design materials yet.

     I would also like to suggest that you employ a geotechnical engineer to investigate the soil on your property. They will be able to determine just what types of loads can be supported and by what types of foundation. They can also help with suggested procedures for preparing the sub grade soil prior to laying a foundation if it needs any type of enhancement or modification to best serve your home’s needs.

     Lastly, I would suggest having an architect review your final design, they are aware of building codes for your area that you may have missed in your initial layout. They might even offer some good suggestions for details on how to waterproof the exterior of your building.

     Anyway, your initial calculation about wall weight is off by a lot, a 10′ x 10′ section of brick should only weigh 4,200 lbs based on your weights and brick sizes. Plus you didn’t account for the weight of your roof, nor for snow, construction, or wind loads. And it seems you are only concerned about the roof being tornado proof… that kind of a design needs to be a whole system approach (walls, foundation, roof, doors, windows, etc.). FEMA puts out some documents to recommend how to create a safe-room, but they don’t make for very pretty homes. I would instead suggest a single safe room made to FEMA standards or better and let the rest of the house blow away. Tornado force winds are too strong for typical construction methods.

     My guess is you would rather not pay the fees for design professionals to come along side and help… but if the building falls down a concrete roof will be devastating. Besides, your local jurisdiction likely requires that you adhere to a building code like the International Building Code. Rather than learn it on your own, along with all the structural design equations, I suggest building a design team to help your dream become a reality.

     Please contact me directly (check my profile for email link) and I’ll help walk you through some of the basics to help get your basic design off the ground before you go to talk to a local professional.

8. QUESTION:
   Foundation Repair Help?
   Hello,

   I kind of have 2 questions but both related to the foundation. We just moved into an older house and it has a stone foundation. Very small basement I guess you could call it a cellar. I’m in the process of raising the middle of the house and noticed that the foundation is in pretty bad shape. I was going to just buy a paint on water sealer when I noticed a lot of the mortar is falling off exposing the rock or it’s getting ready to fall off (very brittle). I read somewhere that you can just clean it up real good and re-mortar it. If so, is that pretty easy to do? I have never done this kind of work but I can be pretty handy and enjoy learning new things. Plus I don’t really want to pay a truck load of money to have someone do it. Do I just take the mortar and fill in all the holes as best as possible and smooth the outside into a good finish or is it more technical than that? Some of the gaps are maybe 5 inches wide and some kind of deep and just pointy rocks. If you’ve seen it before I’m sure you know what I’m talking about. About an 1/8th of the foundation is like this. Scattered around the walls.

   Second question: I’m going to put down some fill dirt around the outside of the house to ensure proper drainage away from the foundation. On the south side of the house the driveway rides along the house and just barely slopes downward into the foundation. Obviously causing a water problem right there against the foundation. I really don’t want to mess with the driveway unless there is no other way. Any suggestions on how to direct water away from the foundation when it’s just a slab of concrete?

   Thanks in advance and I hope I gave enough info.

   • ANSWER:
     Sounds like you have some serious issues but also like you have a good handle on them.

     It is important for the ground to slope away from your house as constant exposure to water will hasten the deterioration of a foundation. While stone foundations can be very strong, often due to their thickness they also tend to suffer differential settlement, leak and spald easily.

     To re-point the stone the loose mortar will have to be removed as much as practical. But in some severe cases may cause instability. Therefore you may wish to work on a section at a time.

     A step more intense would be to install a surface bonding cement over the entire surface of the stone. This will also help to block water penetration. This cement has little fibers in it that act as reinforcement. This can tend to be a little rough finishing.

     A further level would be to pour a new wall in front (or behind) the stone foundation. This can also be reinforced with mesh or re-bar. This would add further support to a weak foundation. To do this you may actually put a form in front of the wall and fill the space with concrete.

     Any type of foundation waterproofing is most effectively done on the outside and most economically done on the inside. If the foundation is not deep you may consider digging on the outside forming up and pouring a supporting wall, surface bonding, and/or pointing from the outside. Once again you have to be concerned about a possible collapse. The risk will determine if you shore up the house, do a very narrow portion at a time or shore up the foundation inside and out. Only someone visiting the site with some experience or an engineer would be in a good position to make such a judgment call.

     There is also a method of epoxy injection for cracks in a foundation that may be worthwhile to research.

     Once you have taken care of the foundation and any back filling and want to resolve the driveway pitch you have several options. First if the amount you need to fill in is over 2″ then you can fill in with concrete and use a surface bonding agent between the two layers. If it is less than 1/2″ then you can use a surface cement like “top and bond” that are intended to be feathered out to a very thin taper. In between you can build up multiple layers of the bonding cement.

     Good luck with your project.

9. QUESTION:
   A concrete answer (front stoop)?
   Our 20-year-old front stoop is surrounded by brick (like the
   crust in a pie). The concrete center of the stoop (5’x5′) has
   gradually settled front to back by about 1 1/2″ to 2.” Can
   fresh cement bring the stoop up to snuff? If not, is there
   a concrete-like material loaded with plasticisers that would
   grip the surface of the old concrete and look attractive? In
   the end, will the old cement have to be broken up and be
   carried away only to be replaced entirely? I do not intend this
   to be a DIY project.

   • ANSWER:
     I would recommend a contractor that deals specifically in ‘mud jacking’.

     A contractor that does this type of concrete repair will come to your home, and pump a cement slurry under your existing concrete, to bring it up to the proper level.

     This method is used to repair foundations, or slabs.

     You can probably find someone in your area that does this type of work, it has become quite common.

     Good Luck

10. QUESTION:
    Basement cement pad not poured correctly?
    I have a working radon system which is supposed to pull air from under the basement floor. When standing in my basement, I can the air being pulled down where the basement floor meets the cinder block walls. My question is this: Is there supposed to be a gap between my floor and walls where air can be pulled from my basement? Was my concrete floor poured correctly?

    A bit more information: There is a small track that runs around the perimeter of the floor. The track runs to the sump pump pit. My assumption is that this is to channel water to the sump pump if required. As I look in the track, I see places where there does not seem to be enough concrete to finish the track. I see stones instead of finished concrete. My assumption is that when the pad was poured the concrete mix was not worked into the track and hence there is not a good bond between the floor and the walls.

    I poured some water in the track, and sure enough, the water did not run towards the sump, it ran down between the walls and the floor. This is the same path that the air is taking.

    Do I have a defective floor or is this a normal thing? Is the floor designed to let air and water in and out of my basement? Please let me know. Thanks!

    • ANSWER:
      Shrinkage is normal: The basement floor concrete is placed/poured last and even though it was poured directly against the wall (or perhaps some joint material), concrete shrinks as it cures and dries. It is quite normal for about a 1/16″ wide shrinkage joint to develop between the edge of concrete and foundation wall. The joint may even be a bit wider if excess water was used in the concrete mix, a common occurrence in residential work.

      Why Repair? Your situation would normally not present a problem (unless water or insects were coming in through the joint) but since you have a radon mitigation system installed, it is important for you to seal the joint at the intersection of floor and wall. You want the mitigation system primarily drawing radon impregnated air from beneath all of the slab, and that will not happen if it is also drawing air from your basement, as the exhaust fan is designed to remove a certain amount of air.

      The Fix: There are numerous methods and products available to seal the joint. I’d wire brush the entire length (to improve bond) and then use “Polyurethane Caulking For Repairing Cracks in Concrete”. You’ll probably want the tubes that are used in a standard caulking gun – you can also get the self-leveling type but be careful as it tends to flow to where you don’t want it. Polyurethane will bond much better than silicone and will expand and contract as the concrete does. Follow the directions on the tube. I give you much credit for recognizing that radon is dangerous over time and your system was not working quite properly.

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