Sheet rock mud on hardboard

[AndyS]

I have a room done in 4 X 8 sheets of hardboard, 1/4" thick, from Home Depot. The "rough" side is the room side. The "rough" side has a grain on it about like screen wire. The "slick" side is shiny.

Has anyone tried to use joint compound on the "rough" side of hardboard to coat or texture it ?

I am concerned if the compound will "stick" as well as to drywall, and whether I should wet the hardboard before applying it ?

Thanks for any informed opinions on this...

Andy in Eureka, Texas

[Steve Barker TB]

Informed opinion? Yes, you could skim coat it, BUT:

#1. but since it's 1/4" thick, it'll flex if someone touches it the mud will fall off.

#2. If you have sheetrock behind it, disregard #1.

#3. If you don't have sheetrock behind it, you are in violation of building code. Not that i EVER worry about that, but you are advised.

s

[PeterD]

Also consider that the backside may soak up moisture from the mud, warp, and appear wavey.

IMHO, rip it out and do the job right with proper sheetrock.

[Handplanes]

Joint compound sticks to glass - it will certainly stick to the textured side of hardboard. As others have said, the moisture from the compound might present problems. You might use a quick drying primer to seal the hardboard before applying the mud.

You have a bigger problem in what to do about the joints, and how much mud will be required. It might be more effective to install drywall over the top of the hardboard. As Steve said, depending on your location and code, hardboard might not meet the requirements.

R

[AndyS]

Andy comments:

My thanks to all who have posted now and in the future...

I have taken a square foot of hardboard and plastered it with joint compound....

When it dries, I will test it, flex it, beat it, and try to determine the "stickitivity"..... and I'll try to report back here what I have learned... It'll take at least a day.

I don't understand why hardboard can't be used as panelling or why it would be prohibited by code. It is not prohibited where I live, and I'd like to know the reasoning for why some codes would not permit it.....

Thanks,

Andy in Eureka, Texas

[jamesgangnc]

Wallboard has a higher flame rating. Fire propigates through it more slowly. Hardboard does not meet code in this use. I would rip it out and do it right. Your test is only going to test the immediate adhesion. You also need to consider issues of mosture absorbtion and differing expansion/contraction rates.

[Handplanes]

You are not required to understand code requirements, or to agree with them. You are required to conform to them. The reason hardboard is not acceptable as a wall sheathing is because of flame spread ratings.

Georgia Pacific's site lists "wall and ceiling panels" as uses for hardboard, but that is for paneling which is required to be on top of plaster or drywall to meet code requirements. There are hardboards that meed the flame spread rating requirements, but unless your product is marked as such, it doesn't.

[Dave in Houston]

I agree that the BEST course would be to remove the wallboard and install new drywall. The hardboard should come down in whole sheets.

If you insist on texturing the hardboard then Liquid Nails the joints as flat as possible with a putty knife. Roll the entire surface(s) with a coat of KILZ. Mud texture. Paint.

Dave in Houston