I’m currently designing a walk-out basement for the back of my house. The house s on clay soil, and has some minor settling problems (drywall cracks above the corners of the doors, etc.). A lot of the houses in this community have this kind of problem, especially the older houses. Anyway, I was considered as part of the slab to drill some piers down into bedrock if it’s not too expensive. My father-in-law, who will be the contractor for the project, thinks that a slab won’t budge and that piers would be overkill. I’m not so sure, I think a slab might move in the heavy clay soil we have. Who is right?
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Listeners write in about removing masonry chimneys and ask about blocked ridge vents, deal-breakers with fixer-uppers, and flashing ledgers that are spaced from the wall.
Featured Video
Highlights
Fine Homebuilding Magazine
Fine Home Building
Follow
-
Fine Homebuilding
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial Now -
GBA Prime
Get instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
- Home Group
- Antique Trader
- Arts & Crafts Homes
- Bank Note Reporter
- Cabin Life
- Cuisine at Home
- Fine Gardening
- Fine Woodworking
- Green Building Advisor
- Garden Gate
- Horticulture
- Keep Craft Alive
- Log Home Living
- Military Trader/Vehicles
- Numismatic News
- Numismaster
- Old Cars Weekly
- Old House Journal
- Period Homes
- Popular Woodworking
- Script
- ShopNotes
- Sports Collectors Digest
- Threads
- Timber Home Living
- Traditional Building
- Woodsmith
- World Coin News
- Writer's Digest
Replies
I'd consult a soils engineer. It depends on what kind of clay it is. If it is an expansive clay like Bentonite you need professional advice anyway. If it isn't one of the most important things to do is to create a drainage plane under the slab with at least 6" of 3/4" clean sharp stone and perf pipe to a sump pit. I'd also use both fibermesh and wire mesh, or possibly rebar in the slab.
Jeff
if the clay stays wet, you will be fine, If the clay stays dry you will be fine, but if wet clay dries or dry clay wets, then you have major headaches.
I have busted out many slabs that has a big gap between the dirt and slab, maybe they did not compact the dirt too well. I have seen many garage slabs poured with the footings, they seem to have the biggest crack in the middle. The slabs with the least amount of cracks are poured after the stem walls are up, with perimeter felt joints, fully compacted dirt and deeply scored joints. So, I would recommend a floating slab.