Advice on Foundation Excavation

[Egon]

Quote:
How do you do a perimeter drain when you can't get to daylight?
Might have to use a sump pump.

Sorry about the confusion. I meant place the pump in a well outside the walls just below the footer depth or frost depth.

 

[dave1949]

Thank you guys

I've understood all posted

My primary residence has perimeter drain going to daylight

The lot in York will not permit that to happen

I was thinking a perimeter drain would not be needed as there would be crawl space but on second thought I'm guessing the idea is for the perimeter drains to get the water away from undermining the footings

How do you do a perimeter drain when you can't get to daylight?

Joel

I would site the foundation elevation such that you create a 1/2" per foot surface slope away from the house in all directions for at least 30 feet.

30' X .5"/ft = 15" So, if you are starting with a level site, where the frost wall emerges from the soil is 15" above the site grade. The bottom of the footer needs to end up 4' below that level, or (48"-15" = 33" below site grade level.)

Since the footer is 8" thick, a standard 4' high frost wall would have 23" exposed above grade. Your bottom row of siding laps over that by about an inch, so from siding to dirt would be 22". (8" footer + 48" wall) = 56" - 33" below site grade level = 23". Hope my math is right 23" is three steps up with a 7" stair riser height.

A daylight drain should be run with a 1/8" to 1/4" per foot slope. You are looking for some place that is 33" lower than the bottom of your footer. At 1/4" per foot, it takes 132' to drop 33". (33"/.25")

If you can't find that on the lot, I guess my next choice would be to run your drain pipe out 50" or so in the lowest direction and let it run into a pit full of rocks lined and covered with a couple layers of filter fabric before backfilling.

I would definitely put in foundation drains. You want the crawl space as dry as possible. Sump pumps are okay but not maintenance free and you have to pump the water somewhere.

It could be you put in drains and hardly any water ever comes out of them, it depends on the water table and surface drainage. If you avoid gutters, as all Mainer's should , your roof will be draining into the ground next to your foundation anyways. You will not have a problem with that if you have good foundation drains.
Dave.

 

[dave1949]

The cheapest solution would be hire a 953 to dig you a shallow basement to the depth of the bottom of your footer. Stake out the excavation 34 x 50 and have the bottom of the excavation be close to 32x 48. Strip the topsoil, dig the hole, spread fill to the rough grade, put in the driveway. Use 10' lengths of thin wall PVC for footer drains. The roll pipe doesn't like to lay straight. Put a sump pit inside the foundation and connect outside drain to it. Fill inside of foundation with stones to top of footer. Pour 4'' slab.

The 953 can do a much better job in a day, than your tractor can do in a month.
Plus you will not kill your tractor. Once the dirt is loose you can kill your tractor backfilling, and trenching utilities.

That works too

The drawback to slabs in that area ( I used to live in Wells, two towns up the coast) is back in the 80's people were slopping in slabs that didn't hold up. They gave slabs a bad name. The real estate market is not kind to them. Most people prefer a basement around there.
Dave.

 

[SixHoeBob]

That works too

The drawback to slabs in that area ( I used to live in Wells, two towns up the coast) is back in the 80's people were slopping in slabs that didn't hold up. They gave slabs a bad name. The real estate market is not kind to them. Most people prefer a basement around there.
Dave.

What I meant was; Dig a hole, pour footers, build frost wall on footers, pour slab inside wall on top of footers. A crawl space without a concrete floor is a lifetime of agony. The floor helps keep the wall from pushing, and makes working in the crawl space bearable. Better yet is to have the crawl space walls 96" high. :thumbsup:

 

[2manyrocks]

If this home is arriving in two sections, you also need to be thinking about an interior section of foundation--either one wide enough to support both sections in the middle or two smaller ones unless the set up crew is good enough to set both sections and join them together "just right."

There are a lot of dirt crawl spaces out there. If you don't have your drainage right, however, down the road you may be blaming yourself saying, "why didn't I....."

Your best/easiest/least costly opportunity to get it right is now before you put a house on it. Corrective action later can be a pain.

 

[JoelD]

Thanks all!!

All posts are helpful, Dave thanks for keeping it super simple for me.

Also, I saw the insulated concrete forms for the firs time yesterday, yes they look very easy.

So I guess you'd form up the footer in a typical manner with 2x8's (google told me the 8 inches I guess code will determine), on undisturbed soil if at all possible. Pour, vibrate air out? then level off and let dry. Then stack up the insulated forms and then fill them with concrete? When you say pumped, does that mean it can't be poured into the forms?

The lot is 80 by 100, from the high point in the lot, to the low point in the lot is maybe 12 inches or so in slope. The longest run from foundation to lot line would be about may 30-40 feet.

I don't think there is anyway I can get to daylight from the footer. Sounds like a rock pit maybe the only option?

Another good point by more than one on the excess soil, a good thing is the road is private and is full of holes, could use some fill for that, likely to have excess fill.

Joel

 

[JoelD]

If this home is arriving in two sections, you also need to be thinking about an interior section of foundation--either one wide enough to support both sections in the middle or two smaller ones unless the set up crew is good enough to set both sections and join them together "just right."

There are a lot of dirt crawl spaces out there. If you don't have your drainage right, however, down the road you may be blaming yourself saying, "why didn't I....."

Your best/easiest/least costly opportunity to get it right is now before you put a house on it. Corrective action later can be a pain.

Good point on the center, I'd not thought of that. Typically how is that done? A piling of sorts?

Joel

 

[Egon]

Then stack up the insulated forms and then fill them with concrete? When you say pumped, does that mean it can't be poured into the forms?[/QUOTE

Using a concrete pump makes it easy to place the cement truck and reach the forms to be filled.

Will you be using rebar and have the walls tied into the footer?

For center support check with the modular supplier.

 

[Bigturk]

Also, I saw the insulated concrete forms for the firs time yesterday, yes they look very easy.

So I guess you'd form up the footer in a typical manner with 2x8's (google told me the 8 inches I guess code will determine), on undisturbed soil if at all possible. Pour, vibrate air out? then level off and let dry. Then stack up the insulated forms and then fill them with concrete? When you say pumped, does that mean it can't be poured into the forms.


A footer for ICF is a little wider than a typical frost wall. The ICF that I used was a total of 12 inches wide, with a concrete core of 6 inches and almost 3 inches of foam on each side. I poured footers 20 inches wide and used a 2x10 for thickness. Place vertical rebar every 2 feet or so, into the footer to tie the wall pour to the footer. A pumper truck cost me $450 extra but made the pour easy. The concrete mix for ICF is thinner and yes it can be poured directly into the ICF from the delivery truck. You need to be able to get to all sides of the pour. Get the footer as close to level and square as possible as this makes the ICF installation easier. Many contractors in my area are using ICF for additions and frost walls. Anyone with good DIY skills can work with ICF using basic tools. The added benefit to the ICF is that your frost wall is insulated, helping keep your floors warm.

 

[2manyrocks]

Good point on the center, I'd not thought of that. Typically how is that done? A piling of sorts?

Joel

Some folks pour a very wide continuous footer and also make their perimeter footers wide on the theory that whoever is placing the home may need a big "target" to hit. Some installers are good--others couldn't set a home on an airport runway.

This kind of shows the differences in regional practice. In middle TN, they'd pour footers, move the home on the site, and then block up to the home.