I am changing my ceiling over to a cathedral and I need to support the new ridge beam down to the floor. My question is do I need to be concerned with the frost line when I pour a cement pad in the crawl space to support the new post? The crawl space is unheated and location is in Massachusetts. How deep do I need to go? Does the frost line come into play when installing a support structure in a existing unheated crawl space
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support post in crawl space
- Thread starter JeffS
- Start date
my250r11
Sawhorse
Check with local AHJ for frost depth, in general thou yes needs to be below frost line.
FLSTF01
Registered User
If the crawl space is not ventilated to the exterior, has frost-protected wall surrounding it and has conditioned space above it, you do not need to go the 42 or so inches below grade. Frost will not get into an area inside of exterior frost walls, especially with no moisture in the ground there. For that matter, think of a detached or attached garage with a footing for a lally column- 24 x 24 x 12 inches deep-not down 42 inches (or whatever your local frost depth is) like the bearing frost walls supporting the structure.
Now, if the crawl space is open to the exterior, like an enclosed screen porch might be, than yes, you need frost protection.
Now, if the crawl space is open to the exterior, like an enclosed screen porch might be, than yes, you need frost protection.
Msradell
Sawhorse
Yes, that makes a significant difference. Most AHJs will make you go to the normal frost depth for your footings in that situation. Since it will be no heat in any part of the structure it all will be able to normalize at or near the ambient temperatures.
TheCommish
Registered User
since it is unheated all structural support should go below the frost depth, If you do some and not others there will be unequal heaving potential. The little save by not doing the job right will be out way the frustration and expense of fixing it.
Remember if we can afford to do it right; how can we afford to fix it.
Remember if we can afford to do it right; how can we afford to fix it.
Francis Vineyard
Registered User
Do you have an edit button?
FLSTF01
Registered User
By three season cottage, I presume it is sitting on piers and not a full frost wall. if that is the case, then you will need to pour your new footing down to 42 inches or your local frost depth.
The cottage is sitting on a standard cinder block wall foundation. I'm guessing about 5 cinder block high. Not sure what's under cinderblock walls maybe crushed stone. Their is no insulation on the walls The cottage was built in the the 50's. from what I can tell the other supports in the crawl space are just cinder blocks sitting on the ground
FLSTF01
Registered User
If it were mine, I would dig it deep so you don't have to deal with it.