What’s the best type of foundation system for small additions?
workdog2
| Posted in Energy Efficiency and Durability on
What’s the best type of foundation system for small additions (20′ x 28′) & (18′ x 16′)?
Just a straight trench or formed “T” ? Better slab or crawl space ? How to finish & insulate inside of crawl space flooring & block ?
Guess I’m looking for the best solutions for a foundation for small additions here in Michigan as stated above.
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Replies
Kurt,
In your climate zone, most contractors would choose between a concrete slab and a crawl space foundation. The site, the existing grade, and the drainage may affect the decision about how to proceed.
To build a crawl space wall, I would excavate to below the frost depth and pour concrete footings. Then I would pour concrete stem walls. (Concrete block walls have more problems than poured concrete walls.) I would insulate the crawl space walls on the interior. For more information on crawl spaces, see Building an Unvented Crawl Space.
Here is a very inexpensive and non-invasive foundation system that is slowly gaining popularity. What is holding it back is typically conservative builders and structural engineers.
http://www.pinfoundations.com/green.htm
If your jurisdiction requires a soil report, then you may be able to find a geotechnical engineer who can work with the engineers at Pin Foundations and get the plans stamped.
The floor insulation and vapor control details are important: http://www.pinfoundations.com/docs/DP%20SKIRT%20WALL%20PRL%20TO%20JOISTS.pdf
In most cases, this system means:
1. No excavation contractor
2. No concrete contractor