crushed rock, pier block foundation

Started by busted knuckles, October 15, 2011, 04:31:16 PM

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busted knuckles

Hi everyone, great website. I recieved some time from work to start building a small home. I has intended on pouring piers. Now the weather is pretty cold, probably too cold to allow concrete to set at its own pace. I read about digging the hole and using crushed rock with a concrete block on top to support the beam.

This is the question,  would it be better, or good, to first line the hole with a landscaping mesh to keep soil from penetrating the crushed rock? Possibly forming a lump of conglomerate,  subject to frost heaving. Looking forward to your replies.
you know that mugshot of Nick Nolte? I wish I looked that good.

PA-Builder

I see you didn't post your location ... where are you, and how cold actually is it there?  There are techniques that will allow you to pour concrete in cold temps.  I would much prefer a concrete footer/pier below the frost line vs. a crushed rock footer under most circumstances.


busted knuckles

Hi, I added my location. It is in the Okanagan valley in B.C.
you know that mugshot of Nick Nolte? I wish I looked that good.

UK4X4

Crushed rock with a french drain was one of the recomended foundations for me in colorado, with a prefab concrete structure sat on top

not just a couple of blocks


sadly it won't work in my location due to spring run off and too much soil movement

It was fundamentally recomended for the frost heave- but there's more going on in my area than just that

there was no netting or anything - just the drains beneath

John Raabe

Crushed rock that is well drained in stable soil can serve as a footing for PT wood foundations, PT wood piers and concrete piers.

See what is holding up well for buildings built in similar sites to yours.

Your choice can be further influenced by:
• Soil type (no clay)
• Slope (natural drainage on all four sides is best) and
• Expense & size of the building (the more money you will spend on the building above the more you should put into the foundation).
None of us are as smart as all of us.


busted knuckles

Thanks for the replies, I am pretty sure there is clay in the soil, there certainly is in the surrounding areas. It is going to be a 16 x 20 structure with a second floor. I am not sure it would be a loft, as the walls on the second floor are going to be 4' tall.

Little bit of background, the land has been in my family for years, I am not that familiar with the soil content. I suppose this might be a good time to do the glass jar water/soil separation test? Or is that too old school?

I am a gunsmith by trade, with a few years of machining background. I have never built a house, but have done some construction. I will be honest, I have been looking at plans, building techniques online. I think I would be best off with poured piers.
you know that mugshot of Nick Nolte? I wish I looked that good.

John Raabe

Piers have worked well for most folks here, but clay soils can freeze and move piers around. This can be a problem for poured and block foundations as well, but not usually as much.

It would be a good idea to do a bit of testing on the soil.

Here are some guidelines on a simple soil test:

• Does it drain? Did a hole down to footing depth. Keep pouring several buckets of water in until the soil is fully saturated. Fill the hole up to the top with water and see if it will drain in 15 minutes or less. (Best done in wet season when soil is fully saturated.)
• Does it have expansive clay? Dig out some of the saturated soil at the bottom of the above hole. Is it slippery when you rub two fingers together or is it gritty? If you pack it into a jar and mark the top of the soil level and then put it in the freezer, does it expand as it freezes?

If it fails the first test and turns out to be expansive, then you are likely to have foundation problems, especially with shallow pier foundations.

If you do a basement or crawlspace foundation (PT wood or concrete) AND it is properly waterproofed with the footings at or below frost level AND you put in footing drains and backfill with drainage material such as crushed rock, THEN you can likely build a solid foundation even in poor soil. That is why this is the default foundation type that most inspectors want you to build.

If your soil drains well and is not expansive then you have little chance of frost heave no matter what type of foundation you build. You have more options.
None of us are as smart as all of us.