Foundation Question

[homeputter]

I will be building a 30'x26' garage later this year. Our County Building code only requires a footer depth of 18" for garages and out buildings less than 1000 sq ft. The frost level is 30". A footer of 30" is required for a cabin. The county could not give me a reason for the different requirement between a garage and a dwelling. The local contractor says "that is the way we have built garages around here for years and we have not seen any collapses."

Obviously, I don't want spend the money to go deeper if there isn't a good reason for doing so.

The load on a wall for a garage or for a 1 story dwelling would be the same. I am nervous about not having the footer below the frost level.

What do the Building Codes in other cold areas require for garage foundations? Don't they require footings at the frost level?
Are they any different than for a single story dwelling?
Thanks for any input.

 

[K'ledgeBldr]

The best alternative is "Frost-protected shallow Foundation". However, it's not approved in all jurisdictions- mainly because the local chief building inspector is 'old school' and new fangled ideas don't turn on light bulbs in his noggin.

http://www.toolbase.org/PDF/DesignGuides/revisedFPSFguide.pdf

Then again, it becomes a matter of cost- weighing one material against another in terms of the material itself and it's related labor.

 

[Kevin54]

I will be building a 30'x26' garage later this year. Our County Building code only requires a footer depth of 18" for garages and out buildings less than 1000 sq ft. The frost level is 30". A footer of 30" is required for a cabin. The county could not give me a reason for the different requirement between a garage and a dwelling. The local contractor says "that is the way we have built garages around here for years and we have not seen any collapses."

Obviously, I don't want spend the money to go deeper if there isn't a good reason for doing so.

The load on a wall for a garage or for a 1 story dwelling would be the same. I am nervous about not having the footer below the frost level.

What do the Building Codes in other cold areas require for garage foundations? Don't they require footings at the frost level?
Are they any different than for a single story dwelling?
Thanks for any input.

What type of foundation is the County talking about when they say you only need to go 18"? Could the 18" be possibly for a slab with the edges at 18". I would assume either a poured foundation or a block foundation would be below frost line.

I know that here in Ohio on a foundation we had to be at 36" to the footer. Michigan is something like 42". Not knowing where you are at makes it hard to really answer the question. There is more than likely others from your area that can answer the question better.

But if it were me, I would put the foundation to frost line all for the fact that all the houses are built that way. I would want the added security that nothing will go wrong on down the line. Maybe your county just looks at a garage as a secondary storage building and really don't put strict guidelines on it. I would be questioning why he couldn't give you a definite answer as to why the difference.

 

[ConCretin]

Assuming your new garage is not connected to an existing structure you can get by with less frost protection but it really depends on the soils you are building on. If you are on well drained, granular materials, the soil won't expand enough to bother. If not, you should consider going below the frost line or use some rigid insulation as shown in the link K'ledgeBldr provided. There's some good information in there.

Our frost line is 4' deep and I have a 28x32 building on monolithic slab over a gravel base. It probably moves up and down a bit with the frost but it's not noticable.

 

[brownbagg]

the reason a garage can get away with it, is because nobody lives in a garage, if it heaves, its no big deal

 

[Bondo]

I will be building a 30'x26' garage later this year. Our County Building code only requires a footer depth of 18" for garages and out buildings less than 1000 sq ft. The frost level is 30". A footer of 30" is required for a cabin. The county could not give me a reason for the different requirement between a garage and a dwelling. The local contractor says "that is the way we have built garages around here for years and we have not seen any collapses."

Obviously, I don't want spend the money to go deeper if there isn't a good reason for doing so.

The load on a wall for a garage or for a 1 story dwelling would be the same. I am nervous about not having the footer below the frost level.

What do the Building Codes in other cold areas require for garage foundations? Don't they require footings at the frost level?
Are they any different than for a single story dwelling?
Thanks for any input.

Ayuh,... 'round here, yer describin' a Floating Slab for the garage, where as a house needs a full foundation...

Frost depth is 4' here, 'n floatin' slabs are common for garages....
House foundations go 6' or 8' deep, or til ya hit bedrock...

 

[KELLHAMMER]

Makes no sense to not go to below frost for a garage. If it heaves, it could distort the building enough to keep doors and windows for opening or closing properly. Been there, done that.