"sonar" (sono?) tubes instead of full basement for a 16'x26' home addition?

[eShirl]

A good idea, or too great a risk of greater overall, long term cost for a cheaper price tag today?

[Stinky The Clown]

1. Check . With . An . Architect . Or . Structural . Engineer

This particular issue is not unlike getting medical advice on the internets.

What is your soil? How many were you planning? What kind of footers? What concrete mix ought you use? Rebar or not?

Too many questions for amateurs to answer.

[hedgehog]

2. Here's what you want to ask your architect/engineer about:

http://www.sonoco.com/productsservices/tubescores.aspx

[Po_d Mainiac]

3. Up heyuh in the glacier State, it's tough to beat a full foundation.

But if you're close enough to the Statehouse, there might be enough excess hot air to keep the frost at bay.

I spent a couple summers jacking camps in the Belgrades. We did several that were on 6ft pours. (the old adage is get down at least 5ft to get below the frost) A long cold snap without snow cover (esp if the ground is damp) can drive the frost down 6-8ins every 24hrs.

It ain't pretty when one section goes South and the rest stays put.