foundation depth and frost heave?

[WoodchuckDad]

I see the slab reccomendations as being about 5 inches...but I am wondering about frost lines, etc. Because of the grading I have to do on my site, I am going to have the foundation be 9 inches thick I still have some concern about frost heave. Anyone have problems of shifting from ground freezing?

[olddude]

Re: foundation depth and frost heave?

question's

did you disturb the dirt below the 9 inch's

second will pad hold anything else if so make sure they have a joint between them

what is the run off in the area does the water settle here or run off say form higher ground

[WoodchuckDad]

Re: foundation depth and frost heave?

I have actually only dug down 5 inches. Since I am increasing the grade it will bring the soil up to the heigh....perhaps above thepad. I am going to make sure my hole is level compact the earth with a hand tamper and put down a layer of gravel

[olddude]

Re: foundation depth and frost heave?

if you bring grade up over pad you risk water run off from seeping into the
ground below the pad if at all possible keep pad area highest that way all water will run off will flow away for pad area
just a thought if you keep the ground dry under pad frost heave should not be a problem

I'm not an expert just have about 20 years in construction
this is what I've seen done.

[Neil2]

Re: foundation depth and frost heave?

"Anyone have problems of shifting from ground freezing?"

So far, I have never seen any posts reporting problems with ovens due to frost heave.

A well reinforced slab will "float" and not be damaged by frost heaving.

[WoodchuckDad]

Re: foundation depth and frost heave?

to keep the pad up over the grade, I would have to build the pad about 20 inches thick. From the back of the pad to the front of it(86 inches) I have about 4-5 inches of climb. From the front of the pad to the to the point where the new patio area will join the edge of the cement around the pool, it is 17 feet and has a drop of about 10 inches.



I would like to put some kind of increased water drainage into the build...not sure how to do it.

[dmun]

Re: foundation depth and frost heave?

Your slab will do better, and be impervious to frost heave in most soils, if you have a layer of well drained crushed rock under it, rather than pour it on bare ground. If you dig down below the frost line and pour proper footings, then they should be on undisturbed soil.

[Millstone Man]

Re: foundation depth and frost heave?

You might want to add a french drain across the front of the foundation to catch and divert the runoff. Check out the drainage pipe stuff at HD/Lowes. Pretty cheep and well worth it in the long run.

[olddude]

Re: foundation depth and frost heave?

your fine as far as run off goes as long as you pad isn't the lowest point were water collects from pics you should be fine just add rock like you said

[WoodchuckDad]

Re: foundation depth and frost heave?

It's not the lowest, but only by about 4 inches I plan to put a length of french drain in front of it, actually ab out half way down the slope I was gonna do another one and then behind it, in the middle of that space I plan to do a 3rd. There have been a couple heavy rains over the years that pushed a bit of water under the garage door. I'd like to prevent that in the future and since I have worked my back into shape digging, I should do it all now.

[ThisOldGarageNJ]

Re: foundation depth and frost heave?

Everybody has bought up some good points,, I would go with DMUN and pour over gravel.. The French drain certainly wont hurt either.. you would want of course to pitch your slab to the drain aiding the runoff by giving it a place to go...

Cheers
Mark

[WoodchuckDad]

Re: foundation depth and frost heave?

How much of a pitch? currently I have it so that from front to back it is about a 1 1/2 inch to 2 inch drop over the 86 inches. I figured that would allow water to run off the slab and when I laid my first course of block I would mud them and make things level. Does that sound like too much pitch? I can still fix it since I have my forms in and my cement guy couldn't come tuesday like he was supposed to.

[ThisOldGarageNJ]

Re: foundation depth and frost heave?

This is what I found WCD.. which seems to be a pretty general rule,,

To eliminate standing water on your slab, it should be sloped away from existing structures (such as your house and garage) a minimum of 1/8 inch per foot, recommends the Portland Cement Association. If proper drainage is prevented because the concrete slab is wedged between two structures, you may need to install a drain that will collect the water at a low point in the concrete and divert it away.

Hope this helps
Cheers
Mark

[WoodchuckDad]

Re: foundation depth and frost heave?

Well that pretty much tells me my slab is sloped appropriately. Guess I will stop worrying and just get the darn thing done.

[ThisOldGarageNJ]

Re: foundation depth and frost heave?

The only thing worrying ever solved for me was... Ummmmm Hmmmmm ok, nothing... I agree It sounds like you are good to go,, Now just get the *&$#@ cement truck there

Cheers And good luck with your pour
Mark