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Old 09-19-2020, 08:04 AM
 
Location: In a secret bunker under the Cannery
1,060 posts, read 875,130 times
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having seen a lot of damp and musty basements while searching for homes here in Iowa due to the high water table and the many structural issues that seem to be common with basements. largely due to the clay content of the soil from what I'm being told and reading on the internet. I was wondering what people's thoughts are on Piers for a foundation?

seems like piers that provide a crawl space might be preferable to a slab.

basements seem to be just one more thing to be a problem or am I completely mistaken?

welcome any input

thanks so much
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Old 09-19-2020, 08:20 AM
 
Location: IN
21,712 posts, read 38,101,484 times
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Quote:
Originally Posted by robojester View Post
having seen a lot of damp and musty basements while searching for homes here in Iowa due to the high water table and the many structural issues that seem to be common with basements. largely due to the clay content of the soil from what I'm being told and reading on the internet. I was wondering what people's thoughts are on Piers for a foundation?

seems like piers that provide a crawl space might be preferable to a slab.

basements seem to be just one more thing to be a problem or am I completely mistaken?

welcome any input

thanks so much
Or just look at homes in northern Iowa, an area that has no clay soils, problem solved.
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Old 09-19-2020, 08:39 AM
 
Location: In a secret bunker under the Cannery
1,060 posts, read 875,130 times
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we're pretty committed to the southern part of Iowa but thank you for the input

I did not know there was such a difference in the soil composition up north

Last edited by robojester; 09-19-2020 at 09:06 AM..
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Old 09-19-2020, 12:34 PM
 
Location: Bloomington IN
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The reason you don't really see pier foundations in the northern half of the U.S. is because of frost heave. As the ground freezes and warms the concrete piers can shift. You're also raising the house off the ground which will allow for cold and hot air to go under the house even if the space is covered by siding or something around the perimeter. Any plumbing run under the house will have the potential to freeze. Same if here are heating ducts--it will be harder to heat.

Traditional crawl spaces have concrete or concrete block fully supporting the house beams and blocking the crawl space area. Traditional crawl spaces will have the same water issues as basements, but it's often harder to get into them to make repairs.
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Old 09-19-2020, 05:21 PM
 
Location: North Alabama
1,057 posts, read 2,022,352 times
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Quote:
Originally Posted by rrah View Post
Traditional crawl spaces have concrete or concrete block fully supporting the house beams and blocking the crawl space area. Traditional crawl spaces will have the same water issues as basements, but it's often harder to get into them to make repairs.
And the footings for those crawl space walls must be below the freeze and frost heave depths for the location. The concrete/concrete walls that pass through the frost heave zone should ideally be sheathed in some manner to lessen the soils grip on them until they rise above ground level. If you take care not to excavate beneath the house to below the surrounding existing soil levels there should be no moisture in the crawl space. The higher above ground you go with the supporting walls of the crawl space, the easier it will be to make repairs and run pipes and heating ducts.
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Old 09-20-2020, 08:34 AM
 
Location: In a secret bunker under the Cannery
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thank you all for the input

the one we plan to go look at was built in 1995 so I'm hoping it's fairly up to standards

I guess we'll see
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Old 09-20-2020, 06:04 PM
 
Location: In a secret bunker under the Cannery
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put in an offer so we'll see what the inspector has to say
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Old Yesterday, 10:41 AM
 
Location: Iowa
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Well, it's doable but keep it high enough so you can crawl under there to work on it, and you probably will be working on it more often than you think. Not sure what you're going to use for skirting on the outer perimeter, but keep it as airtight as possible, and well insulated. I know on mobile homes, the skirting is very important to keep the pipes from freezing. Snakes, small critters and spiders will find there way in there with great ease. Binding of the skirting where it meets the ground might be a problem too, in winter season.

What I like about piers, you can dig and pour them yourself, frost footings are 42 inches in Des Moines, but for the water & sewer lines, I might go a little deeper just to be sure, especially the main water line. All the plumbing will probably need insulation sleeves and heat tape may be necessary.

I built a large room addition on my home with existing crawlspace, and decided to go with poured walls, but did not dig out for a basement. I kinda wanted a basement, but factoring in wasted space for the stairs, the codes for egress windows and door for fire exit, and how many problems people have with basements, this swayed me to sticking with crawlspace setup. Also, with crawlspace, the pressure is somewhat equalized on the walls because the ground is same height on both sides of the wall after you backfill. So the walls will not push in over a long period of time. I also like having my laundry and water heater upstairs in a dry air environment, where the humidity cannot do damage. I still have the same water heater from 1997 and it works fine, and the one before was over 20 years old and still worked, but was too small.

About the piers, I had to dig out 2 piers to support the main beam, which was a cantilever type beam supported by the new wall on one side, and 2 piers, so the piers had a lot of weight on them. I wanted the beam out of the way so there was more useable space and I wouldn't bang my head on it, when moving things in and out, as it was high enough to walk with a crouch down there. The piers were only about 7 foot apart from each other. Within 6 months a crack appeared above door in new room addition and I discovered one of the piers was sinking. Over a period of 7 years, that sucker sank almost 1 1/2 inches, the other one was just fine and never sank at all. Every couple months I had to get the bottleneck jack out, go down there and put in another shim to properly support the beam. The drought year of 2012 was especially bad. Eventually it quit sinking and I put in a new 6x6 support post. Wouldn't you know, that pier raised up about 1/4 inch over the next couple years and I had to take it back out and trim off a little piece, lol. It has remained stable the past few years now, and I patched and painted the crack above door and it has not reappeared.

I think it's worth it to rent the form panels from construction supplier and go with poured walls and forget about the skirting and all the aggravation those 15 or 20 piers might cause you. I hired a guy with backhoe to dig trench for 500 bucks, built forms for footings 16" wide x 8" deep with rebar, hired pump truck with hose to fill them (I was the guy on the hose), set up forms on top of footings and built a rebar skeleton inside forms as I assembled, and blockouts for crawlspace door and dryer vent, and hired boom truck to pump in concrete, I did the actual pouring and was the guy standing on top of forms guiding the hose. It was not fun but in the end, I paid about 3k for the foundation, 3 walls, one 24 wide and the other 2 were 16', poured all at once. Seems like I used around 5 yards of concrete for the piers & footings, and 12+ yards for the walls, can't remember exactly. I had to do a lot of reading and use plenty of math skills for the project, with lots of cussing mixed in at various points of the project.

There were some small 1 and 2 inch pits visible on the outside walls, I filled them with white silicone caulk, and painted the walls white with foundation paint, looks good. Could have used vibrator but you don't want the large aggregates settling to the bottom as this compromises strength of wall. 15 years out, I only have one tiny crack where they made me block out for 2 small 12x8 vents close to the corners, which compromised the rebar strength a tad where corners join. Looks great where it joins with the old foundation, and helped strengthen the old foundation so it is more stable now. I drilled holes in old foundation at the junction, and inserted rebar with strong epoxy to connect.

Last edited by mofford; Yesterday at 11:41 AM..
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Old Today, 10:39 AM
 
3,600 posts, read 1,236,880 times
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Quote:
Originally Posted by rrah View Post
The reason you don't really see pier foundations in the northern half of the U.S. is because of frost heave. As the ground freezes and warms the concrete piers can shift. You're also raising the house off the ground which will allow for cold and hot air to go under the house even if the space is covered by siding or something around the perimeter. Any plumbing run under the house will have the potential to freeze. Same if here are heating ducts--it will be harder to heat.

Traditional crawl spaces have concrete or concrete block fully supporting the house beams and blocking the crawl space area. Traditional crawl spaces will have the same water issues as basements, but it's often harder to get into them to make repairs.
Your first statement is incorrect, by code, all footing have to extend down below the low frost line in each different geographical area. For instance, in SW Virginia the footing must be 30 inches below grade, in Northern NY, it’s 4’-6” below grade. Each different building department will have their own footing bottom depth which is calculated as being 12 inches below historical freeze data.

You statement regarding cold air being able to circulate under the first floor of a living space in a house is definitely correct. Perimeter walls are a definite benefit!
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Old Today, 05:05 PM
 
Location: In a secret bunker under the Cannery
1,060 posts, read 875,130 times
Reputation: 765
this one was manufactured and set up in 1995

we will be getting both the normal Home Inspection as well as a inspection from a structural engineer

thanks for the tips about sealing it up tight I have seen both sides of the ventilation argument on the internet but sealing it up to prevent freezing makes a lot of sense especially to someone like myself who grew up in Minnesota

thanks for such a thorough answers and so much information!

Looks like we will be closing in early Nov
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