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I’m planning a patio in my back yard and want to incorporate a seat wall along the sides of the patio where the adjoining grade is a bit lower – by about 12″. The seat wall will be about 24″ high and about 24″ wide and made of mortared flagstone. Each wall will be 20 feet long.
I plan to build the wall atop of a footer. My question is – what’s the proper depth for the footer?
Some contractors say that a footer for the wall needs to be below the frost line. Others say that the footer only needs to be about a foot under the soil as long as it sits on top of gravel and is reinforced with rebar.
I live in Northern Illinois where the frost line is 42″ below the surface.
I’ve seen landscaped yards in the area with mortared retaining walls and appear to hold their own – and unlikely have a 42″+ deep footer.
What are the alternatives? Considering that sidewalks aren’t footed below the frost line, can a seating wall be built with the same design? I realize that sidewalks are broken into sections and perhaps I can do the same with the wall.
Replies
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I'm planning a patio in my back yard and want to incorporate a seat wall along the sides of the patio where the adjoining grade is a bit lower - by about 12". The seat wall will be about 24" high and about 24" wide and made of mortared flagstone. Each wall will be 20 feet long.
I plan to build the wall atop of a footer. My question is - what's the proper depth for the footer?
Some contractors say that a footer for the wall needs to be below the frost line. Others say that the footer only needs to be about a foot under the soil as long as it sits on top of gravel and is reinforced with rebar.
I live in Northern Illinois where the frost line is 42" below the surface.
I've seen landscaped yards in the area with mortared retaining walls and appear to hold their own - and unlikely have a 42"+ deep footer.
What are the alternatives? Considering that sidewalks aren't footed below the frost line, can a seating wall be built with the same design? I realize that sidewalks are broken into sections and perhaps I can do the same with the wall.
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Chris,
The contractor in paragraph 3 is probably on with his comments.
Your project wall is only 20 feet and 2 x 2 feet constructed with mortar and flagstones.
If it did crack and shift, it would be so minor that you would wonder what the fuss was about.
Use the money difference to take you wife out to a great dinner.
Good luck.