Foundation on addition if no foundation on original?

[NoMN1955]

I have a 60 year old cabin in Northern Minnesota built on blocks all the way around the 20 x 24 structure but they only go a foot or so below the surface and definitely not below the frost line.  It has not moved at all over 60 years.  If I put an addition on I'm thinking of including a basement, full foundation and everything.  Do I need to put a below frost line foundation on the existing cabin?

[ChugiakTinkerer]

Welcome to the forum!

The advice I've seen on the web is that the addition should have the same type of foundation as the original structure.  That way if there is any ground movement it should be consistent at the transition between old and new.

[MountainDon]

Welcome to the forum!

The advice I've seen on the web is that the addition should have the same type of foundation as the original structure.  That way if there is any ground movement it should be consistent at the transition between old and new.

Agreed. What are the local building rules?

[akwoodchuck]

Dig out under the existing cabin while excavating the addition, putting everything on one proper foundation, - would be my $.02....not too difficult really.....doesn't northern MN have really shallow bedrock?

[Don_P]

We go below frost depth in case the soil can heave, this soil obviously isn't trapping moisture. Sometimes you can vary from best practice.