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Small Cabin Forum / Cabin Construction / What are the options to keep heavy rainfalls from home on concrete slab?
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Myoldhomefallsapart
Member
# Posted: 18 Jul 2021 21:36
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I live in an area with sometimes lots of rain and really cold winters (Kansas).

A local construction company would build me a concrete slab for my 16 x 40 new home. But I don't want to take any chances with the heavy rains in spring.

Do you have any ideas or suggestions for me to keep water away from such a house, dear people?

gcrank1
Member
# Posted: 18 Jul 2021 22:58
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No matter if you are camping in a tent or building a house (no matter the size), you need to be on the high spot so the water runs away. This does not really mean you are the high spot in a low spot! That would make you an island.....for a while. Watching the water rise about you would be a sinking feeling.
Anybody used to doing slabs in your area should be well aware of the potential site issues, local conditions and requirements/permits & approvals before starting. If they arent, you dont want them.
The structure needs to have enough eve overhang and gutters & downspouts to take the roof water away from the house sides and slab and the ground should be properly sloped away also.

DaveBell
Member
# Posted: 18 Jul 2021 23:20
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Dig a small lake or large pond. Look at a topographic map to make sure it is downhill from your slab site. Pile the dirt on the 16x40 spot, 24x48 and compact it.

Brettny
Member
# Posted: 19 Jul 2021 06:30
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The ground should slope away from the slab in every direction. You may need to add a swale for this to work. Site prep is very important and if not done correctly can cost many times more later.

Myoldhomefallsapart
Member
# Posted: 19 Jul 2021 10:33
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Thank you all for your advice. The problem is that there is no high spot on this parcel. I may have to dig a pond and compact it.

But what do you think of French drains?

Or is it better to put the house on concrete piers? The house would be then higher up than with concrete slab, right?

Massive flooding here is considered "unusual", yet, two years ago, people with concrete slabs had to stay up two nights with buckets to keep their homes dry.

frankpaige
Member
# Posted: 19 Jul 2021 10:44
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If, it is that flat? You might consider having fill brought in? If you want a pond? That might be where your fill might come from? Compact, overhangs, soil sloping away, downspouts. Any ideas from the construction company? Inspector?

gcrank1
Member
# Posted: 19 Jul 2021 11:14
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In that case, you need (NEED) a site evaluation by someone 'skilled and knowledgable'.
I know, it complicates things. But, iffn ya start out wrong it is All Wrong from then on.

curious
Member
# Posted: 19 Jul 2021 11:43
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Is this a full-time home?

If neighboring properties have recently experienced flooding and your lot is flat, I would be certain to build higher than what has been done there in the past.

French drains work for their intended purpose but they are no solution to too much surface water.

Concrete piers designed by an engineer will work, in fact, done right, they can be very good. Done right means a full perimeter foundation footing that is as deep as the frost depth. Concrete or masonry piers are then built on that footing, everything ties together with rebar.

Or sufficient fill can be brought in to build a mound. That will require proper compaction. Then a normal slab can be built on that elevated ground.

Myoldhomefallsapart
Member
# Posted: 19 Jul 2021 16:46
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The problem is that my place is so rural that it is hard to find someone skilled and knowledgeable here.

Yes, it should become a full-time home.

We have one construction company here that doesn't even return calls and have a waiting list of 2 years to build anything.

I am 2 hours away from Kansas City. I might have to hire someone from there.

Concrete piers going 3 feet down against frost, is that enough?

Brettny
Member
# Posted: 20 Jul 2021 05:28
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If it's so rural you cant find help and its going to be your full time home I suggest you start going things your self as this is only step 1 in a long process of building and maintaining a property.

Myoldhomefallsapart
Member
# Posted: 20 Jul 2021 13:36
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Concrete piers going 3 feet down against frost, is that enough?

Brettny
Member
# Posted: 20 Jul 2021 13:44
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What's the frost depth?

ICC
Member
# Posted: 20 Jul 2021 16:38
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Quoting: Myoldhomefallsapart
going 3 feet down against frost

As Brettny asked, what is the frost depth for the location? That is the depth the footing needs to be in order to prevent uplift from freezing.

Curious made a good point though with the mention of a full perimeter footing with piers resting on that. Piers or posts as you often see done is not the best foundation. The idea of the full footing is to ensure the bottom of the piers cannot shift. Piers can and do rotate in the ground given the right, or the wrong, circumstances. The top end cannot shift as that is connected to the house. The bottom end could move because it is only held in place by the earth. Depending on the soil type, the moisture content of the soil and other variable environmental factors soil can become mushy or like gelatin.

So, you can probably do whatever you want, being out in the middle of nowhere, so to speak. The foundation method Curious mentioned will provide piers that will be the most stable. Just an FYI, FWIW, pier foundations are generally not approved by any building code, without an engineers input.

Myoldhomefallsapart
Member
# Posted: 22 Jul 2021 11:55
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Hi ICC,

Thanks for this.

I found one contractor here who would make me a slab foundation. Now I have to find one who makes me a full perimeter footing with piers resting on that.

It is nice to live in the middle of nowhere. But not when you need something.

gcrank1
Member
# Posted: 22 Jul 2021 18:00
Reply 


Why do you 'need' piers?
A way better set up is footings and a stub wall to size of the structure and support piers as needed inside that as needed for the spans involved.
Think traditional 'crawl space'. Anybody worth their salt who does 'crete down there should be able to do that.

Myoldhomefallsapart
Member
# Posted: 23 Jul 2021 08:33
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Thanks, gcrank1. I wish I could do this myself. It is hard to find any handyman around here.

ICC
Member
# Posted: 23 Jul 2021 10:09
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Have you asked that one contractor who has done slabs if he can bring in fill and properly compact it to make a flat top mound to place a slab foundation on?

If there was a chance of repeat flooding as has recently happened I would not want a crawl space that could be inundated with water. So my thoughts would be to elevate on a raised slab on a raised filled mound or to elevate on engineered piers. A friend has a home in Louisiana that is on a pier foundation that elevates the house some 4 or 5 feet above grade. Poured concrete piers that are continuous from footing to floor.

Myoldhomefallsapart
Member
# Posted: 24 Jul 2021 00:04
Reply 


Yes, I asked him, ICC. He said that cinder blocks would be the best solution for my foundation. We can get some flooding but nothing like Louisiana.

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