Cement backerboard for risers/stages

Does cement board even have strength in this way? It doesn't seem super sturdy.

I have still a lot to learn about Home Theater construction but, as a contractor, I would never use cement boards as the only flooring material for a riser or spanning a framed floor, if that is what you are asking. That is not it's intended use. You could perhaps use it on top of a layer(or 2) of plywood or OSB to add extra mass but I will leave that with someone with more specific knowledge of riser construction to answer.

100% agree that cement backerboard should go over a plywood base, But then you need to consider how carpet will be attached. Not sure you can easily use carpet staples.

You could use it for vertical faces.

A place to save money is the base for the riser, You can use smaller boards for all the interior joists and just do some mid span supports. For example if you are using 2x12s for the perimeter you could use 2x6 or 2x8 for all the interior joists.

BIGmouthinDC said:

100% agree that cement backerboard should go over a plywood base, But then you need to consider how carpet will be attached. Not sure you can easily use carpet staples.

You could use it for vertical faces.

A place to save money is the base for the riser, You can use smaller boards for all the interior joists and just do some mid span supports. For example if you are using 2x12s for the perimeter you could use 2x6 or 2x8 for all the interior joists.

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Wouldn't a carpet installer just use the same nails and tack strips as they would on a normal concrete floor?

Rojolo said:

I have still a lot to learn about Home Theater construction but, as a contractor, I would never use cement boards as the only flooring material for a riser or spanning a framed floor, if that is what you are asking. That is not it's intended use. You could perhaps use it on top of a layer(or 2) of plywood or OSB to add extra mass but I will leave that with someone with more specific knowledge of riser construction to answer.

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This was my thought. Have a 3/4 layer of OSB and a 2nd layer of cement board.

gimmepilotwings said:

Wouldn't a carpet installer just use the same nails and tack strips as they would on a normal concrete floor?

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Maybe, this is uncharted territory for me, ask a carpet installer.

BIGmouthinDC said:

Maybe, this is uncharted territory for me, ask a carpet installer.

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Might not be worth the $150 in lumber.
Glad I was able to put you in uncharted territory.

gimmepilotwings said:

With lumber prices still high, has anyone used/considered cement boards instead of OSB for their risers/stages? You can save about 50% over lumber prices using this instead.

Thoughts?

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Lumber prices are coming down. Just wait.

squared80 said:

Lumber prices are coming down. Just wait.

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My carpet installer will be here in about 2 weeks so unfortunately I can't wait. c'est la vie

I suppose you could make the cement board layer the bottom layer and put the plywood on top.

Yeah, not sure it is worth the trouble of cutting the cement board as well...