Painted Durock (or hardibacker) for Heat Shield

[pen]

Came across a dangerous situation a buddy has that needs a heat shield on a dime.

Wondering if anyone is using straight durock (or hardibacker) with the 1 inch spacers for air space behind it, that is simply painted for a side heat shield.

If so, how's it holding up?

Was standard or high heat paint used?

Also, how brittle is durock? I've only ever worked with hardibacker before. Wondering if it would be better to use hardibacker instead of durock for a standalone situation like this. Where it's located it should not be abused once up, just never worked with the stuff to know how brittle it is compared to the hardi

Thanks for the help

pen

 

[firefighterjake]

The Durock I used (not the Next Generation) seemed pretty rugged . . . I mean I wouldn't put it between two floor joists without some type of sub-floor, but for a heat shield that is out of the way where it shouldn't get bashed I would imagine it would work well enough. Some of the left over pieces of Durock I have had kicking around in the garage look fine . . . after being buried under assorted pieces of sheetrock, scrap wood, etc.

 

[pen]

The Durock I used (not the Next Generation) seemed pretty rugged . . . I mean I wouldn't put it between two floor joists without some type of sub-floor, but for a heat shield that is out of the way where it shouldn't get bashed I would imagine it would work well enough. Some of the left over pieces of Durock I have had kicking around in the garage look fine . . . after being buried under assorted pieces of sheetrock, scrap wood, etc.

That's great, thanks Jake. It'll save me about 10 bux in gas and an hour and a 1/2 to get the Durock versus hardibacker.

Now, wonder how putting paint on it would go. hmm.

 

[David Tackett]

Durock is cement board and much better than hardibacker, IMO, for this application.

 

[firefighterjake]

That's great, thanks Jake. It'll save me about 10 bux in gas and an hour and a 1/2 to get the Durock versus hardibacker.

Now, wonder how putting paint on it would go. hmm.

Maybe try a paint made to go on to cement . . . other than that . . . many of us have our stoves pretty close to the walls and don't have anything up on the walls other than painted sheetrock . . . no problems with the paint (although I have had issues with cracks in the sheetrock -- but that's a whole other thread.)

 

[Tramontana]

I would recommend wearing a mask or respirator if you use power tools for cutting. Also, pre drilling pilot holes will help reduce spalling the face of the Durock.

Another option for finishing would be to go with a gypsum veneer plaster that has an integral color.

Good luck.

 

[milleo]

Durock next generation worked great for me but I did tile over it. Use a carbide blade when cutting it, I got 3' x 5' sheets and it is lighter than the old style durock.

 

[BrowningBAR]

That's great, thanks Jake. It'll save me about 10 bux in gas and an hour and a 1/2 to get the Durock versus hardibacker.

Now, wonder how putting paint on it would go. hmm.

I put some up on the one side of the chimney that faces the stove (in the living room that has the Defiant in it). The chimney was old and left exposed for 100+ years as it was attached to a built in cabinet that we removed. We attached Durock to the chimney to provide a smooth surface to allow us to match the other two sides of the exposed chimney inside the home.

It worked well, but we are finding that the paint does not hold as well and tends to crack. We redid it this summer and it is holding up better, but we have two noticeable cracks in the paint. One crack is up top near the ceiling, the other is where the pipe enters the chimney.

So, we will probably touch it up again this summer.

 

[Dakotas Dad]

I just added some concrete color to some mortar, and more or less stuccoed.. been three years now.. still looks good. Your color choices are limited though..

 

[turbocruiser]

I'll echo all the above comments and add that perhaps the "paint" to use in this instance is that "UGL DryLock" paint that is specifically spec'd for concrete? It is designed to penetrate into and bond with the cement to prevent leaks, cracks, chips, etc. I imagine that would be the best type for longevity but I have not idea how it handles the heat. Ohh, don't use HardiBacker it is cellulose based and not actually cement based and I think that most of it has a grid design going through it too so that might not match the rest of room. In any case avoid HardiBacker for this application . Hope that helps.

 

[pen]

Thanks for all the advice guys.

This heat shield is going behind a double barrel wood stove in a buddies cabin. Since nobody has ever sat around a double barrel stove and ogled at it's beauty, I think the natural look of durock will be just fine. Certainly a lot better than burning the joint down. How it has never burnt before is beyond me. I thought maybe if others had good luck in the past, that I'd paint it with some leftover stuff while I was there.

Thanks again,

 

[begreen]

Came across a dangerous situation a buddy has that needs a heat shield on a dime.

Wondering if anyone is using straight durock (or hardibacker) with the 1 inch spacers for air space behind it, that is simply painted for a side heat shield.

If so, how's it holding up?

Was standard or high heat paint used?

Also, how brittle is durock? I've only ever worked with hardibacker before. Wondering if it would be better to use hardibacker instead of durock for a standalone situation like this. Where it's located it should not be abused once up, just never worked with the stuff to know how brittle it is compared to the hardi

Thanks for the help

pen

I did this for the Jotul 602 when it was installed in the kitchen. Painted Durock with high temp white. It wasn't the most attractive shield, but stood up well. We had no issues for the 12 yrs it did the job.

 

[pen]

I did this for the Jotul 602 when it was installed in the kitchen. Painted Durock with high temp white. It wasn't the most attractive shield, but stood up well.

Good to know,

 

[begreen]

IIRC it was engine paint. Nothing special. It never peeled or anything.

 

[bag of hammers]

Used 1/2 Durock in my original camp install with metal furring strips (leftover bits) for spacing. This was before the "next generation" product so I can't speak to the newer stuff. No paint (didn't care about aesthetics). It's been up for over 10 years now although I haven't run that stove in a couple years. I used leftover pieces of metal furring strip close to the edges and I had no problem. As mentioned, dust mask when cutting, and only cut outside (sorry that's probably obvious, but it makes a ton of silica dust and huge mess). But I did find it easy to make a nice smooth cut with an old skilsaw circular saw and standard masonry blades.

 

[BillT]

I would cut the old Durock by scoring and snapping with a special scoring tool.

I haven't tried the new stuff yet, but can that be still scored and snapped?

 

[turbocruiser]

I would cut the old Durock by scoring and snapping with a special scoring tool.

I haven't tried the new stuff yet, but can that be still scored and snapped?

It can be but it is best to cut with circular saw with special blade and while also wearing dust mask. This produces the smoothest cut.

 

[Tramontana]

Yes, they now are marketing specialty saw blades for cementitious products such as Hardipanels and Durock.

Wish they had been available when I needed them instead of destroying decent carbide toothed blades.

Cheers!

 

[northernontario]

If this is just going in a cabin, why not use a metal sheet? I used a 4x8 sheet from a HVAC/duct work shop... The metal reflects heat instead of absorbing it... gives you a higher reduction in clearances (more effective).

Of course the smaller 3x5 sheets are easier to work with. I also used some 1/4" hardibacker boards in my install. It's all in the basement... pretty was not a requirement. Every person who came to inspect (building inspector, WETT inspector, insurance inspector) said it was one of the best installs ever. I have a layer of cement board over the old drywall and exposed studs, and then the air gap and clearance reduction barrier (metal or more cement board). In one spot I did a double air gap... although code only allows a max of 67% reduction (metal sheet), it's wood studs + air gap + cement board + air gap + metal sheet. Those studs stay nice and cool... but they're about 7" from some single-wall black pipe.

 

[pen]

Got things all put back together last night, and used the durock. Much safer than this setup has ever been in the past.

Used a 1 1/4 inch air space. It's amazing to look at this installation before, and know how close that barrel stove burned to the pine board wall when it would be glowing. Very lucky nothing every happened.

Everyone's happy now. Thanks for the advice guys.

pen

 

[begreen]

That's got to be much safer. Did you end up painting it or is it just raw Durock?

 

[pen]

That's got to be much safer. Did you end up painting it or is it just raw Durock?

It's raw, and to be quite honest, doesn't look that terrible considering it's in a rustic cabin. The stove is in an out of the way area, and certainly not the center of attention. I mentioned having some paint that I could use on it (high heat like you mentioned) and that comment evoked a bunch of belly laughter.

It was a bit step for them to accept the need for the heat shield in the first place.

 

[BillT]

Just for what it is worth, when I was checking on the Micore I was looking for, I asked the guy at the USG Headquarters about the "new" Durock. He told me that it has a better R-Value and has increased to .39, but at the same time he said the Fire Resistance was reduced down to 125 degrees.

Just for curiosity, I asked him if the old stuff was still available and he said that no, it wasn't.

Maybe we should update our info that we have on record. I would recommend to verify what I was told though to make it official.

Bill

 

[raybonz]

Just for what it is worth, when I was checking on the Micore I was looking for, I asked the guy at the USG Headquarters about the "new" Durock. He told me that it has a better R-Value and has increased to .39, but at the same time he said the Fire Resistance was reduced down to 125 degrees.

Just for curiosity, I asked him if the old stuff was still available and he said that no, it wasn't.

Maybe we should update our info that we have on record. I would recommend to verify what I was told though to make it official.

Bill

He told me that it has a better R-Value and has increased to .39, but at the same time he said the Fire Resistance was reduced down to 125 degrees.

That makes no sense to me at all... There is no way you're gonna ignite this cement board especially at 125 degrees!

Ray

 

[pen]

but at the same time he said the Fire Resistance was reduced down to 125 degrees.

That is not correct. Next Gen durock is fine for heat shields. Cement boards such as PermaBase are not ok.

Here's the literature on it (broken link removed)

Here's the cliff notes version:

The board is non-combustible and can be used in a variety of fire-rated designs. Its low thermaland hygrometric expansion help prevent finish cracking.

DUROCK cement board Next Gen includes a wind load rating of 30 PSF and is UL Classified for fire performance. It offers a 30-year transferable warranty for interior applications and a 10-year transferable warranty for exterior applications.

pen