# how to join 3/16" hardboard floor edges?



## gfixler (Feb 21, 2009)

I'm helping a buddy buddy tomorrow to build a seamless wall. We're framing out a 2×4 stage floor with 3/4" ply on top, then on top of that goes a surface of 3/16" hardboard. Adding difficulty is that near the wall we're curving things up along curved plywood ribs (think fins with 90° circles cut out, ~3.5' radius), so the hardboard will be bent smoothly up those ribs to create a backdrop with no corner seam for his photo work. It's a big area - stage will be about 16' square, and the thing I'm most concerned about is the seams. The whole idea here is that this stage will be seamless, but I'm worried that over time the seams will shift, especially around the curve. I'll be lashing the framing together with strong, long screws, and really clamping and tapping everything into perfect alignment first, but the hardboard might still shift a little - just enough to show the seams through the paint after a year or two of wear and tear. We thought of things like tape (e.g. for spackling), but tape is going to show up through paint as seems, and wear out terribly and visibly over time. I'm looking for a few things here:

1) something to seal these joints that's hard, but gives a bit, and can be sanded and painted - this would help hold those seems together and smooth - something like a joint compound, epoxy putty, spackle, wood filler, etc

2) a primer we can lay down after sanding everything smooth that other paint will adhere to - he's going to be painting it with a roller as needed for photo shoots

3) a durable paint that we can apply in layers (i.e. so he can repaint without stripping), which won't flake or peel, even after lots of hard wear (exterior latex? I have no idea - not my area)

4) any kind of topcoat for the paint to make it super easy to remove footprints (it's a dirty warehouse - I'm envisioning a million black prints on matte paint, as we had in our cheap productions back in my school theater days) - this could also be a moot point if the paint is something easy to mop down and resilient to things like foot traffic - I'm kind of picturing the stuff they use in prisons that can't be chipped or peeled off, even with things like pocket knives - nice and durable, easily washable, not glossy (flash photos will be killed by gloss background), and able to be painted over again and again in different colors (mostly black and white)

I would greatly appreciate any help in this area. Thanks very much!


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## mdedm (Aug 18, 2009)

I've always used sawdust mixed with wood glue for a filler. I don't know if this would suit your purposes, though, as it may not be flexible enough. It might be worth some experimentation, though.


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## CharlieM1958 (Nov 7, 2006)

I'm thinking something like painter's putty?


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## Jack_T (Feb 6, 2010)

If your lumber is construction grade lumber it will probably continue to shrink as it acclimates to the warehouse. If you put the hardboard down on top immediately, the movement of the stage frame may pull the hardboard sheets apart regardless of how you have joined them. To minimize wood movement, in addition to screwing the plywood to the stage frame, you should use construction grade adhesive between the floor joists and the plywood subfloor.

If cracks do develop I would sand the surrounding area back to the hardboard, fill with wood putty, resand and repaint.

I don't know what covering to use on the hardboard.

Good luck, let us know what you decide to do.


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## gfixler (Feb 21, 2009)

Thanks, folks. I will take all of this into consideration and report back on what we decide at some point in the near future.


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## PG_Zac (Feb 14, 2009)

Gary,
If you're looking for tough paint, find an industrial paint supplier and ask for a two-pack epoxy paint. That stuff is HARD, and stands up to all sorts of punishment. The project I'm on at the moment uses this stuff in an acid atmosphere and it looks good after months of abuse from clumsy workers dragging crates around.


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## drewnahant (Dec 10, 2009)

I would position your hardboard so that your bend is in the middle of the sheets, and the seems are in the flat area, no stress, they should hold up well, and I would just make sure that all seems are bridged by the backing material, wheter that is the mdf, or the plywood ribs, attatch with construction adhesive so that it is fully supported ( screws or nails only attatch intermittently, glue will hold the seem better). it should last years without any visable wear.


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