More Musings of an Energy Nerd
How do you build a residential foundation in Fairbanks, Alaska? The answer depends on site conditions — especially soil conditions and the presence or absence of permafrost. The answer may also depend on whether or not you think the climate is warming. Juggling all these factors is tricky, which is why some Fairbanks builders who followed best practices for foundation design ended up with buildings that are now leaning or sinking.
From a construction viewpoint, Fairbanks has terrible soils. Some neighborhoods are underlain by permafrost that is hundreds of feet thick; in these areas, only the top few feet of soil ever thaw. Other sites formerly had stable permafrost — permafrost which is now melting. Still others never had permafrost — they just have unstable soils that are tricky to build on.
Even builders who have sought the advice of engineers have learned the hard way that an expensive foundation won’t always keep you out of trouble.
Difficult soils
If you drive through certain Fairbanks neighborhoods, you’ll see lots of examples of buildings that appear to have sunk or settled unevenly. There is no single explanation for all of these foundation failures; each failure is unique. But taken together, these failures represent a cautionary tale for foundation designers.
According to a 2017 news article by Emily Gertz on a web site called News Deeply, “Soils in Alaska’s second-largest city are marred by discontinuous permafrost. They’re unpredictable and dynamic and they shift and change, sometimes dramatically from season to season. … ‘There’s a lot of bad things happening with soils,’ said [structural engineer Tim] Henry. ‘I mean, compared to just four or five years ago, there’s a lot more [problems]. Seeing the properties that have been there for a long time and then move after 20 years, that’s real scary, because no…
Weekly Newsletter
Get building science and energy efficiency advice, plus special offers, in your inbox.
This article is only available to GBA Prime Members
Sign up for a free trial and get instant access to this article as well as GBA’s complete library of premium articles and construction details.
Start Free TrialAlready a member? Log in
5 Comments
Ah - that's where I left my vice-grips!
We just lifted the corner of our 1938 community hall. There wasn't room for jacks, but luckily it is next door to the fire hall and we were able to borrow air-bags from them to slip between the footings and beam. One scott-pack of compressed air later and the building was up 6".
I can honestly say the "vice grip holding the house together" is a new one for me. Fascinating take on geotechnical engineering complications in the North.
Thanks Martin; I’m sending this to family members In reference to our North country fishing camp where cribbing would be the perfect solution to our ever-falling piers. My brother in Fairbanks is looking at either replacing his shorter piers with 50’ ones or going 100’ to ledge for a much higher cost. And for the record, they use a holding tanks for both septic and water. His addition 30 years ago was the first place I saw European triple glazed tilt-turns.
Bob,
I'm glad at this article gave you some ideas. Good luck!
THe most interesting building jacking in the world is in Venice; where they use huge airbags to hold up
600 year old multi story buildings made of masonry while they replace the wood pilings that have held them up out of the mud for all of those years. Yet, it is not clear whether the old city will survive in an age of rising ocean waters
Log in or become a member to post a comment.
Sign up Log in