Can you use cement board outside?

[paperfist]

I know kind of an odd question, it's cement after all. I've never heard/seen it be used outside.

I want to build a little waterfall for my 2 tub "pond" and the best idea I've come up with so far is to make a sort of stair stringer out of pressure treated. Cover that with cement board and then get some of those mosaic look alike stones and cover the cement board with that.

Anyone know if this will be a fail?

 

[DrPizza]

That doesn't sound like it woud fail, to me. I've done a couple of waterfalls - but I accomplished them by just building up a pile of mostly rocks, with either rubber roofing or thick black plastic hidden inside, collecting any water that trickles down backwards, and returning it to the waterfall/pond. Almost seems like the addition of hardibacker would be "overkill" for the project, though the stuff is cheap enough that it doesn't matter, plus would add some rigidity to it. I take it you're looking for a more formal look, rather than a natural look.

 

[Elixer]

I know someone who used Durock cement boards outside...
Did a quick look up, and it shows Warranty (30 years for interior and ten years for exterior applications) is transferable.

So, looks like it should work.

 

[paperfist]

That doesn't sound like it woud fail, to me. I've done a couple of waterfalls - but I accomplished them by just building up a pile of mostly rocks, with either rubber roofing or thick black plastic hidden inside, collecting any water that trickles down backwards, and returning it to the waterfall/pond. Almost seems like the addition of hardibacker would be "overkill" for the project, though the stuff is cheap enough that it doesn't matter, plus would add some rigidity to it. I take it you're looking for a more formal look, rather than a natural look.

No actually I wanted a natural look, but space is limited to about 4 sq' behind the first pond tub. *poor planning* I have some pretty large 6 - 12" stones they I pulled out of the ground while planting trees, but I haven't come up with a way to use them.

I was going to do it in a similar fashion to yours, but I wasn't sure if I'd get enough flow to actually have the water flow over the rocks and not just sort of muddle around them.

I also wanted to get a 20 gallon or so pail under the water falls so I'd have extra water capacity.

 

[paperfist]

I know someone who used Durock cement boards outside...
Did a quick look up, and it shows Warranty (30 years for interior and ten years for exterior applications) is transferable.

So, looks like it should work.

Thanks! I wasn't even aware that stuff had a warranty. I usually just tile over the stuff and forget about it.

 

[echo4747]

OP, I do know people are using cement board (along with steel studs) faced with stone or tile to build outdoor kitchens which are becoming quite popular now. I think cement board may work for your application too.

 

[WHAMPOM]

I think I remember a show where they applied cement board to enclose a porch to railing height, screwed to a treated wood frame and then glued fake stone over the cement board.