Frost Protection For Retaining Walls and Fences

[bookowski]

Situation: Small rear yard that will be lowered such that is approximately 24" below the adjacent yard on each side. On top of the small retaining wall there will be a new fence, possibly brick masonry but possibly something more flexible.

Is the minimum frost depth required for situations like this? That's 4ft in my case. The code states 'for buildings and other permanent structures'. It is quite a bit of work to excavate a continuous trench 4ft in addition to the 2ft lowering of the yard - this will require engineered sheeting and shoring drawings for the building department. I am just wondering if this is excessive for a fence and small retaining wall. What is the risk of not adhering to this and going with say 24"? Frost heaving may damage the fence? Any chance of it leading to instability of the wall?

 

[dik]

Check with the building official... if you don't mind it moving you may be able to use less than 4'. 4' is more permanent.

I don't like to use brick in contact with soil.

Have you considered segmental pre-cast walls?

Dik

 

[bookowski]

Thanks. If it is a brick fence I would still be using a concrete wall that extends above grade, probably 8", and then the wall would sit on top. and the wall would get a brick face. Just wondering what people typically do in this situation, it seems very costly for a fence.

 

[MiketheEngineer]

Versa-lok or equal

 

[cvg]

it's even more costly to knock it down and re-build it after a few years. but this is the way contractors think, warranty is only 1 or 2 years and they are long gone. build your "fence" right the first time

 

[bookowski]

That's the question, is it really the 'right' way to do it? The wall will only be about 20ft long. With the footing/retaining wall assembly I would think the it would be rigid enough to move as a whole and not crack anything sitting on it. It would not be tied into any other components. I just don't want to be overly conservative if it's not necessary.

MiketheEng - I have recommended versa-lok, thanks - they just wanted to know the requirements if they did not go this route.

 

[CANPRO]

you could always insulate for frost protection... 2'x2' trench shouldn't be a big deal.

 

[cvg]

option a) the soil is not frost susceptible, then there is little risk of heave
b) place a layer of non frost susceptible soil below the footing
c) use 4 feet deep round pile footings to support your wall