I'm trying to come up with a good detail at the doorway of an industrial building. I'd planned on having the perimeter grade beam come up about 6" above the slab on grade and leave the slab on grade 'floating'. But at the doorway, throw a couple of dowels in and notch the gradebeam down 6", or would you notch it further and run the slab over top at the doorway. It's been a while since I've designed a concrete foundation and I can't remember what is (or if there is a) standard way to detail the door openings.
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Slab on Grade at Doorway
- Thread starter chris457
- Start date
If you are in an area where frost heave is a concern, you are asking for trouble of you don't dowel the doorway stoop into the building and provide a perimeter frost wall.
The dowels will prevent the stoop from heaving and blocking the door at the doorway and the frost wall will prevent frost heave and keep the stoop from becoming unlevel (preventing the door from swinging open)
The dowels will prevent the stoop from heaving and blocking the door at the doorway and the frost wall will prevent frost heave and keep the stoop from becoming unlevel (preventing the door from swinging open)
We usually drop the perimeter grade beam below the slab and have the slab extend over the grade beam to the outside face of the grade beam.
This results in a single slab joint (between interior slab and exterior pavement) instead of two twin joints on either side of the grade beam, with the grade beam top exposed.
As far as heaving, if we drop the grade beam and extend the slab over the top, there is a concern (as MotorCity mentions) of the earth just inside the grade beam freezing and heaving.
However, you can and should have perimeter insulation placed on the inside face of the grade beam anyway (in non-door areas) and this insulation (usually 2" thick rigid in our region) would extend up the inside face of the grade beam and turn horizontally under the slab for 2 feet or so. This protects that dirt from heaving to some extent.
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This results in a single slab joint (between interior slab and exterior pavement) instead of two twin joints on either side of the grade beam, with the grade beam top exposed.
As far as heaving, if we drop the grade beam and extend the slab over the top, there is a concern (as MotorCity mentions) of the earth just inside the grade beam freezing and heaving.
However, you can and should have perimeter insulation placed on the inside face of the grade beam anyway (in non-door areas) and this insulation (usually 2" thick rigid in our region) would extend up the inside face of the grade beam and turn horizontally under the slab for 2 feet or so. This protects that dirt from heaving to some extent.
Check out Eng-Tips Forum's Policies here:
faq731-376
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