Foundation decision

[builderboy]

Rather than use the existing foundation thread, I'll start my own. I have to make a foundation decision soon. I'm building in a relatively low area - not hard core flood plain but water flowing thru is possible from a nearby stream during extreme flood conditions. There will never be standing water on my land, just flowing thru to lower nearby land. I'm in Nova Scotia which has similar climatic conditions to coastal Maine with full winter conditions.  I want to build 2 feet above grade and cannot have a full basement. MY options are:

1) footing below frost and frost wall extending 2' above grade with a 2' crawl space from grade on up. My concern with this is crawl space humidity management. I don't want to incur the cost of conditioning a closed crawl space and the open vented space has humidity issues which concern me.

2)  A concrete contractor suggested same as above but fill the Crawl space with rock (tamped down) and pour a raised slab at 2' above grade. (requires burming up above grade outside)  This would eliminate the crawl space concern but I'm reading some negativity on slabs on the other foundation thread.

Opinions appreciated.

Thanks

[glenn kangiser]

It pretty well eliminates being able to change anything under the slab easily but is common down here with slab foundations.

You are not interested in anything like the Bigfoot foundations -?

[PEG688]

The water flowing thru part is a big concern I'd have .  Even with that raised compacted slab,  undermining would be quite possible .

Where you the one who asked about water flowing thru and how to devert it a week or so ago??

So site unseen , I'd try to create swales / mounds that should devert the water as much as possible  around the building .

I'd  use a big foot or similar footing / post & pier system that was hell for stout cross braced , so IF that water was carrying any debris   the bracing and post should withstand / shed off that debris .

Set the footings below your frost line . Use PT 6x6 post with stout metal concrete to post connectors , inbedded in the concrete of course. And stout post to beam connectors.  

I'd go with a light weight / almost "break away " metal roofing type skirting , and I'd vent it . I'd make that skirt easy to rip off / not stout so IF that water is worst than you've seen it and was dragging junk the skirt would peel off but the hell for stout post and pier would , hopefully, survive.  

I know your worried about a vented crawl space , which I don't quite understand if the venting is adquiate how would it trap moisture ??  N. S. is not New  Orleans  , so termites / high humidity are they that big a issue ??  

So a sort of 3 pronged plan .  

[Amanda_931]

I'm with PEG on the swales and ditches, mulch basins and maybe mounds upstream.  They can slow water down a lot.  Swales and mulch basins are useful in dry areas to concentrate moisture so that you can grow things that seem to take more water than your area has.   As well as slowing down erosion.

But any thing that slows down erosion is a good idea.  I've got to do that down by the barn.  Not quite sure how to start it, though.

[glenn kangiser]

You might look up the hill above the barn, Amanda,  and start by seeing what you can divert above it.  I read an article - linked it somewhere I think about water management beginning at the top of the hill - if you take care of it there and on down, then you won't have a problem at the bottom.  About a guy in China.  Don't remember the title - my mind is gone. :-/

[JRR]

Phlo Don Heal?

[glenn kangiser]

You almost had me there, JRR.

That may have been the title.  I think the author was Sum Ting Wong.

[Amanda_931]

Retaining wall with drains into a stock tank for irrigation will probably take care of it.

But I'd really like to hire that done.

Don't see many places to catch it below that, though.

[tc-vt]

A frost protected shallow foundation (slab foundation with polystyrene insulation boards buried around the perimeter) is another design option.  It has worked well for me so far in northern VT and is a good do-it-yourself project.

Some pictures are at

photos.yahoo.com/ny2vermont

Tom