How much foundation settling is too much

[Goldwinger]

Hello,
I would really appreciate any thoughts on the scope of a proposed foundation repair solution on my house.

My living room floor has a very noticeable bounce and sag that has gotten progressively worse over the last 23 years (house was built in 1999). I called out an engineer who determined the floor joists and a support beam were under-supported and suggested sistering joists. It has been impossible to find someone that is willing to do this work of sistering joists. So I called a foundation company who offered an alternative solution of using additional pier supports with steel beams to reinforce the existing structure. As a side note, our city planning department said a permit would not be required in either approach since no demolition of the existing structure would be happening.

The person from the foundation company found a .9 inch deflection in the area of the sagging (shown as item #1 in picture below) and another area of deflection in the area of a kitchen island (item #2 in picture). We expanded the length of the island almost two years ago and had a large, heavy granite countertop installed. I was suspicious that something might be happening in this area but the flooring in this area is 3/4” hardwood flooring so it wasn’t as obvious.

The foundation company is reputable and while the representative that came to our house was knowledgable and helpful, he also had a salespersons approach. We question the need for the additional pier supports in the other areas of the foundation. His proposal would add eight more piers (in addition to the four we know we definitely need) and more than double the cost of the work. Is a .5” drop over a 15 foot distance a significant settlement amount and enough to warrant pier and steel beam reinforcement? Taking the two areas of concern we know we need to address out of the equation, do the other deflection numbers suggest the settling is not uniform and therefore more of a concern?

The picture that follows is a sketch of our foundation. The joists run north to south intersecting two very large support beams that run down the center of the house east to west. The numbers that are -0.5 are points along those large support beams.

Thanks in advance for any feedback on what the right thing is to do here.

 

[oldognewtrick]

First off, welcome to House Repair Talk.

Next, get a couple other estimates. I'd also suggest contacting a structural engineer and get their reccomendation. It's usually not very expensive to consult with them if they don't have to write a report. And, it could save much more than their consulting cost.

 

[tomtheelder2020]

I am a little confused. The title of your post indicates foundation settlement but your description indicates the problem is settlement (bowing) of joists that need, but don't have, foundation support in the middle.

How much settlement is too much (either foundation or joists)? If you think the settlement is significantly slowing or has stopped, then it is just a cosmetic question of what you are willing to live with. If settlement is ongoing, I would definitely want to stop it.

Sistering the joists (presumably including jacking up the sagged areas to restore level) sounds like professional handyman level work so the question is why you can't find anyone to do it. Are they too busy to take it on (common for many building trades in my area)? Afraid of liability if the repair fails? The answer to that question might help you find someone to do the work or might help you decide which option is best.

 

[bud16415]

I have lived in lots of old homes with bowed floors. When I look at houses I take a golf ball or marble and it gives a quick view of how bad they are. I think the OP phrased the topic foundation but the real problem is some homes built in that era were sized a little on the light side and with loading in a lot of weight and time things bowed or will bounce.



I would ask the OP if the basement is finished or plans of finishing and will all these posts be in the way?





Secondly does he want the floors stabilized or does he want them brought back up? Sometimes straightening that amount could cause other problems with inner walls cracking or doorways binding etc. Sometimes you can take some of the bow out and call it good enough and then turn to stabilize.

I had several bad spots in my old house and when I did work in the basement adding some walls I took that opportunity to fit the new walls very tight and that took all the bounce out above. I wasn’t trying to make load bearing walls but they are stabilizing.

 

[Goldwinger]

First off, welcome to House Repair Talk.

Next, get a couple other estimates. I'd also suggest contacting a structural engineer and get their reccomendation. It's usually not very expensive to consult with them if they don't have to write a report. And, it could save much more than their consulting cost.

Thank you. I contacted the engineer that came out initially and asked if he would review the suggestions of the foundation company but the engineer declined citing potential liability issues. He doesn't want to be linked to any company doing the actual work since he can't guarantee quality. I would feel better having an engineer review the plans so I will dig further into this. Having another party look at the foundation is a good idea and we do have another foundation company coming out in three weeks.

 

[Goldwinger]

I am a little confused. The title of your post indicates foundation settlement but your description indicates the problem is settlement (bowing) of joists that need, but don't have, foundation support in the middle.

How much settlement is too much (either foundation or joists)? If you think the settlement is significantly slowing or has stopped, then it is just a cosmetic question of what you are willing to live with. If settlement is ongoing, I would definitely want to stop it.

Sistering the joists (presumably including jacking up the sagged areas to restore level) sounds like professional handyman level work so the question is why you can't find anyone to do it. Are they too busy to take it on (common for many building trades in my area)? Afraid of liability if the repair fails? The answer to that question might help you find someone to do the work or might help you decide which option is best.

I titled the post as foundation settlement because the foundation company report stated we have "significant foundation settlement". But your question brings up the point that the areas of the most deflection are a result of sagging joists and not the result of sinking piers. So if -.5 inch over 15 feet is not considered significant settling, maybe we don't have a settlement issue and it's more that a foundation company looks at things through the lens of a problem being settlement since they only offer foundation services and not carpentry services. In regards to finding a handyman to help, I live in the Seattle area and labor is very tight. The focus seems to be on kitchen/bath remodels, decks, etc. and they don't want to do crawlspace work. Only foundation companies have interest and respond to our inquiries. Thanks.

 

[oldognewtrick]

Thank you. I contacted the engineer that came out initially and asked if he would review the suggestions of the foundation company but the engineer declined citing potential liability issues. He doesn't want to be linked to any company doing the actual work since he can't guarantee quality. I would feel better having an engineer review the plans so I will dig further into this. Having another party look at the foundation is a good idea and we do have another foundation company coming out in three weeks.

If you have the engineer write a scope of work, then you can have several companies bid the work based on his recommendations. Then, you have a level playing field.

 

[Goldwinger]

I have lived in lots of old homes with bowed floors. When I look at houses I take a golf ball or marble and it gives a quick view of how bad they are. I think the OP phrased the topic foundation but the real problem is some homes built in that era were sized a little on the light side and with loading in a lot of weight and time things bowed or will bounce.



I would ask the OP if the basement is finished or plans of finishing and will all these posts be in the way?





Secondly does he want the floors stabilized or does he want them brought back up? Sometimes straightening that amount could cause other problems with inner walls cracking or doorways binding etc. Sometimes you can take some of the bow out and call it good enough and then turn to stabilize.

I had several bad spots in my old house and when I did work in the basement adding some walls I took that opportunity to fit the new walls very tight and that took all the bounce out above. I wasn’t trying to make load bearing walls but they are stabilizing.

Neat idea about the golf ball. We have a lot of wood flooring so that would be easy to test out.

We have a crawlspace and not a basement. There are a lot of things in the way so the steel beams (that will be attached to the pier supports with brackets) won't be continuous and will be broken up around the obstacles (beams, ducting, etc.)

I am concerned about wall cracking and such. So far, that has been very minimal although some are popping up around the top of door frames (only vertical and on one side of the doorway though so maybe that is normal after 23 years and sheet rock related?). We would want at least the area that has the floor sagging brought up (measured at .9 deflection). It's a very noticeable dip in the floor. The report states they will raise this area 1/3 inch. The proposal for the other areas is to just support at the existing state and not bring up the beams/flooring. If they go slow enough with the other areas, could we avoid cracking altogether or is it unrealistic not to expect some? We have a tiled bathroom floor on the second floor above much of this work so we are also concerned about that being affected.

 

[bud16415]

Is the house built on a continues footer and wall around the perimeter or is it built on block piers each having their own footing?



Different areas of the country I see this done different ways and some of it has to do with frost line depth. Where I live even a house with a crawl space has a full footing and full walls and most even have a poured floor in the crawl space. That’s the reason almost all just go with basements. We see crawl space where there are high water tables.



Is your crawl space have a floor or just dirt?

Any chance you are thinking of making this a DIY project?

 

[tomtheelder2020]

Joists can only sag if the span between piers is too great, in which case the easier solution might be additional piers, or if the piers are settling under the weight of the joists. It was not my primary area of practice but my 37 year career as an engineering geologist gives me theoretical, and some practical, understanding of foundation settlement. If the perimeter foundation was settling, while the interior piers remained fixed in place, the floors above the piers would be bowed up. Therefore, IF there is foundation settlement, it must be the interior piers settling. For that, there are only two likely scenarios. The first is bearing failure, where the overloaded footing shears the soil and pushes laterally, resulting in settlement. The other is consolidation of soil below the pier; the soil is squeezed into a denser state, again resulting in settlement. Bearing failures happen but are relatively rare in residential construction. In either case, the most direct solution would be to dig new deeper footings under the piers (or adjacent to the existing ones). If the problem is consolidation, and the under-compacted soil is deep, that could be a more difficult problem - but potentially solved by a footing that is wider but not deeper. You should clarify with the engineers exactly what they think is happening. If they don't dig into the soil to examine it and collect soil samples at least as deep as the footings they are guessing (though guessing based on experience in that specific area can be pretty accurate).

Digging new footings in a crawl space is difficult, dirty work done mostly, if not completely, by hand*. The companies you are talking to may simply not have any employees willing to do that kind of work. Keep asking around and ask specifically about new interior footings. Thinking outside the box, if you can get a design for new footings from an engineer you might find a landscaping contractor with employees willing to dig in difficult conditions. The downside of that solution is that, if it doesn't work, the engineer will deny responsibility because you didn't use an appropriate contractor and the contractor will deny responsibility because they just built it the way you specified. Whoever you use, make sure they are licensed and insured - you don't want to be sued if one of those laborers gets hurt on the job.

If it was my house, I would just put screw jacks (NOT hydraulic) on a couple of concrete pads in the sag area, then jack the joists up a half inch or so. That will removed load from the existing piers so I would drive wedges to restore the load onto them. It might be necessary to dig down a little to be sure the concrete pads are on firm soil. A year or two later, if settlement hasn't resumed, a ton of money was saved. If the sag is back to where it was before, you are back to where you started but not out that much time or money. Oh, and if the screw jacks do fix the problem, I would probably replace them with foundation piers - sometime in the next 10 or 20 years**.

*Drilled or driven interior footings can be done. I have never seen it but understand it is generally considered an option of last resort.

**Of course, the jacks would likely collapse under earthquake loading but if it is a M8.5 on the subduction zone you will have bigger problems than a sagging floor.

 

[Goldwinger]

If you have the engineer write a scope of work, then you can have several companies bid the work based on his recommendations. Then, you have a level playing field.

I think it is wise to pull in an engineer again as you suggest. When I had an engineer come out last Fall to look at the sagging issue, I didn't realize another part of the floor around our new-ish expanded kitchen island was "sinking" as well. Once the foundation company pointed it out, I can feel it. So I didn't have the original engineer look at this area because I didn't see this problem. Now that I know I have a bigger problem, a re-call appt would be a good idea. On a side note, around here the foundation companies still want to come out and look before they'll bid. I tried to make it easy to get bids by sharing the engineering report with the foundation companies up front but that only got me appointments. Thanks.

 

[Goldwinger]

Is the house built on a continues footer and wall around the perimeter or is it built on block piers each having their own footing?



Different areas of the country I see this done different ways and some of it has to do with frost line depth. Where I live even a house with a crawl space has a full footing and full walls and most even have a poured floor in the crawl space. That’s the reason almost all just go with basements. We see crawl space where there are high water tables.



Is your crawl space have a floor or just dirt?

Any chance you are thinking of making this a DIY project?

The house has a perimeter footing (all around) and interior to the house are probably eight or so large concrete pads that the house also rests on. The perimeter of the foundation is fine with no cracks and, thankfully, no one mentioned settlement there. The floor is dirt with plastic on top. Apparently no water or moisture was found. We have a pretty temperate climate in Seattle and have maybe twenty or so days that make it (mostly) just below freezing. I was considering DIY when I thought the problem was limited to just the floor sagging in one room and was trying to get bids to decide if the effort was worth it but then the foundation company came up with other areas they think need reinforcement and that eliminated my DIY thoughts. Thanks.

 

[Goldwinger]

Joists can only sag if the span between piers is too great, in which case the easier solution might be additional piers, or if the piers are settling under the weight of the joists. It was not my primary area of practice but my 37 year career as an engineering geologist gives me theoretical, and some practical, understanding of foundation settlement. If the perimeter foundation was settling, while the interior piers remained fixed in place, the floors above the piers would be bowed up. Therefore, IF there is foundation settlement, it must be the interior piers settling. For that, there are only two likely scenarios. The first is bearing failure, where the overloaded footing shears the soil and pushes laterally, resulting in settlement. The other is consolidation of soil below the pier; the soil is squeezed into a denser state, again resulting in settlement. Bearing failures happen but are relatively rare in residential construction. In either case, the most direct solution would be to dig new deeper footings under the piers (or adjacent to the existing ones). If the problem is consolidation, and the under-compacted soil is deep, that could be a more difficult problem - but potentially solved by a footing that is wider but not deeper. You should clarify with the engineers exactly what they think is happening. If they don't dig into the soil to examine it and collect soil samples at least as deep as the footings they are guessing (though guessing based on experience in that specific area can be pretty accurate).

Digging new footings in a crawl space is difficult, dirty work done mostly, if not completely, by hand*. The companies you are talking to may simply not have any employees willing to do that kind of work. Keep asking around and ask specifically about new interior footings. Thinking outside the box, if you can get a design for new footings from an engineer you might find a landscaping contractor with employees willing to dig in difficult conditions. The downside of that solution is that, if it doesn't work, the engineer will deny responsibility because you didn't use an appropriate contractor and the contractor will deny responsibility because they just built it the way you specified. Whoever you use, make sure they are licensed and insured - you don't want to be sued if one of those laborers gets hurt on the job.

If it was my house, I would just put screw jacks (NOT hydraulic) on a couple of concrete pads in the sag area, then jack the joists up a half inch or so. That will removed load from the existing piers so I would drive wedges to restore the load onto them. It might be necessary to dig down a little to be sure the concrete pads are on firm soil. A year or two later, if settlement hasn't resumed, a ton of money was saved. If the sag is back to where it was before, you are back to where you started but not out that much time or money. Oh, and if the screw jacks do fix the problem, I would probably replace them with foundation piers - sometime in the next 10 or 20 years**.

*Drilled or driven interior footings can be done. I have never seen it but understand it is generally considered an option of last resort.

**Of course, the jacks would likely collapse under earthquake loading but if it is a M8.5 on the subduction zone you will have bigger problems than a sagging floor.

Your mention of possible soil compaction underneath the interior piers got me to remembering that the foundation was poured in the late fall. Our rainy season usually flips on like a light switch around late September/first of October. The soil had to have been very wet and for at least a couple of months prior. It was also a very wet winter (we visited frequently as the house was being built).

Yes, I don't envy anyone that has to work in a crawlspace, not to mention having to dig holes for pier supports in such a tight area. Our crawlspace height is about three feet. Adding new piers (and steel beam supports in some areas) is what the foundation company is proposing. The piers they are proposing to use are adjustable by wrench so thanks for clarifying the difference. It's good to know you might have used a similar solution given similar circumstances.

 

[bud16415]

I’m 66 going on 67 and I would still conceder such a project as DIY but I would likely find a younger friend to help me and if that wasn’t available a couple older friends. With 3’ of headroom I think it is something workable and I assume you have access to get under the house.



With your climate and the area of concern being under a conditioned house and that the house is now actually fully supported and what you are wanting to add is stability more than anything else. It could be a project where you work at it a little at a time. I personally would design some mini support columns and find a local weld shop to fabricate them. maybe a plate steel base to spread out the contact area and then use 4x6 wood beams to span 3,4,5 joists to push against.



One thing about a DIY solution besides saving a lot of money is you could slowly crank things up going down there once every other month and giving things a turn.

This 1870s house we live in now I have been thinking of doing something similar. We have a basement but with fieldstone foundation and 6’2” head room it will never be more than an equipment space and root cellar and where we keep the outdoor folding chairs in the off season. I also added a good size kitchen island and the living room has some bounce. Having 3-4 posts down there wouldn’t hurt a thing. I just need to get the ambition to do it along with 200 other projects.

 

[Steve123]

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