Pier and beam house question

[TFM]

About 3 years ago, I purchased and old Victorian house that had been moved onto a lot and set on piers.  I believe he piers are concrete poured in place, and approximately 2 feet square.  Quite a few piers are under the house.  There are not too many pier and beam houses in my town here in Central Texas, and I've noticed a few movement issues in my home - a few cracks in the sheetrock, sticky doors and the like.  Is this to be expected in pier and beam houses?
Tim

[Robert Adams]

It's common in all houses here in tx because of the extremely high clay content of most of the soil here. At least with pier and beam you can correct the problems easily however with a slab it's a mortgage loan to fix... 


     Whatever spots that sink just get under there and jack them up and shim them. Add extra floor joists or sister beams as needed. Unfortunately here in tx pier and beam was popular up until the late 60s. The issue is few were done well and I have yet to see any crawlspace here proper height and properly sealed. 

         Our house was built in 1960 and in this small area the soil is pure sand and many houses were built pier and beam. The piers are round concrete who knows how deep and 7' on center. There will always be some sinkage in sand and we had some cracks and sagging appear a couple years ago because of the earthquakes we were had due to the waste water injection wells. 
       In the areas with clay I have seen houses heave after heavy rains and sink in the summer. I have seen separately poured pads and porches heave up to 3" in the fall after a hard rain and dry summer. So basically here if you don't have cracks and sticky doors you will eventually it's just the soil here and house foundations aren't built to handle it. Though the post tension slabs do handle it well longer but it's not uncommon for voids to eventually form under them over time (poor compaction and uneven expansion of soil).

[Wild Turkey]

Which part of Texas?

There's several different soil types in that state

[TFM]

About 3 years ago, I purchased and old Victorian house that had been moved onto a lot and set on piers.  I believe he piers are concrete poured in place, and approximately 2 feet square.  Quite a few piers are under the house.  There are not too many pier and beam houses in my town here in Central Texas, and I've noticed a few movement issues in my home - a few cracks in the sheetrock, sticky doors and the like.  Is this to be expected in pier and beam houses?
Tim

Thanks for the replies fellas.  Wild Turkey, my home is in Boerne, about 25 miles NW of San Antonio.  Although a lot of places around here have limestone rock about 8" below ground, I think I may be atop an old river bed as I'm about a block away from the Cibolo river and the dirt here is pretty sticky and black.  I'm betting that it was deposited here thru the ions as the riverbed turned  back and forth as they do thru geologic time.

Robert, thanks for the info.  I'd suspected that these problems are common with pier and beam homes.  I guess that slab construction overtook pier and beam due to the relative increasing costs of labor in the overall building expenses?  Anyway, I'll crawl under the house and have a look during the holidays.  Main problem I can foresee is that I had the underside (under the floors) sprayed with foam insulation last year in an effort to increase energy efficiency.  Hopefully that won't hide the sags too much.  If you have any more tips as to what to look for, I'd appreciate it!
Tim

[Robert Adams]

Thanks for the replies fellas.  Wild Turkey, my home is in Boerne, about 25 miles NW of San Antonio.  Although a lot of places around here have limestone rock about 8" below ground, I think I may be atop an old river bed as I'm about a block away from the Cibolo river and the dirt here is pretty sticky and black.  I'm betting that it was deposited here thru the ions as the riverbed turned  back and forth as they do thru geologic time.

Robert, thanks for the info.  I'd suspected that these problems are common with pier and beam homes.  I guess that slab construction overtook pier and beam due to the relative increasing costs of labor in the overall building expenses?  Anyway, I'll crawl under the house and have a look during the holidays.  Main problem I can foresee is that I had the underside (under the floors) sprayed with foam insulation last year in an effort to increase energy efficiency.  Hopefully that won't hide the sags too much.  If you have any more tips as to what to look for, I'd appreciate it!
Tim

           
              Yeah slab construction is cheaper and faster and personally I hate any type of suspended floor. I like a solid concrete floor under my feet. I hate the deflection, creaks sagging and other issues that suspended floors have no matter how well they are made.  Also pier and beam is quite pricey to do correctly these days. Basically you treat it like a short basement which is really what it is. Concrete runs around $90 a yard and only the plumber has to run his drains and the water feed through the slab. All water feed is done above slab now. And if it's a post tension slab like most houses the slab uses little concrete and is much less likely to crack over its life.  

          Your insulation would have been better done on the exterior wall and then encapsulating the crawlspace. It requires much less insulation and leads to better humidity control under the house and makes repairs easier in the future. Tease a look at the building science web site as they have a very good writeup on best practices. 
          If you do spray foam then basically everything needs to be covered in foam. If the joists aren't they will condense water and cause rot. 

               Don't be surprised to not only find sags but to find some areas that are raised up a little. Also many times doorways and walls will dip down cause back then they thought that thick subflooring was suitable for walls. They didn't care if there was a floor joist under a wall that ran along with the joists. In fact many were built with the walls between floor joists because they could run the electrical straight down under the house to the next wall instead of through the attic. 
              I'm so glad they don't build houses like they used to....

[Lynden]

In road construction lime is used to stabilize clay soils by mixing lime with the subsoil and compacting. Clay soils can also be stabilized by pressure injecting a lime slurry.

http://www.concreteconstruction.net/how-...or-soils_o -- (3) explains pressure injection

RamJack has a San Antonio office. Call them and explain your situation. Ask them if there is an affordable way to stabilize the soil under your piers and perimeter foundation.

https://www.ramjack.com/ram-jack-solutio...injection/

[Snipe Hunter]

There's going to be movement in a home. Particularity in a new home or a home on a new foundation. Unfortunately, it's a pain but things do settle down after a while.

A lot of houses were lifted a couple feet (three cinder blocks higher) in my area after the last tidal surge flood from Hurricane Ivan (iirc). Every one I've inspected has stress cracks in the sheet-rock at the tops of doors and windows. Several have stuck windows and binding doors.