Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by Gooserider, Sep 11, 2007.
How's wonderboard for cutting?
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Cutting wonderboard was easy in a straight line with an abrasive bit in my circular saw. Cutting holes was pretty easy by drilling smaller holes around the perimeter and then knocking out the center. I then nibbled the perimeter smooth with pliers.
The stuff is heavy though at 96 lbs per 3x5 sheet.
Note on cutting Wonderboard, Permabase, Durock, etc.
If you read the directions sticker stuck to the board. It clearly states not to cut with a saw, grinder, etc. The stuff in there is not good to breathe.
The directions on mine specifically said to cut with a utility knife or similar. Exactly what I did, and worked perfect. And no dust mess, power cords, or power equipment needed. Just score with knife and snap. Pretty much same procedure as cutting drywall. Just a suggestion.
Uh oh, I may die soon.
Better you than me
I cut all my hardibacker with a saw, much faster. Just wear a good mask and goggles, the dust will dry out your eyes bad. And hell it cant be any worse then the pack of smokes I take in a day.
Wearing mask and goggles it isn't terribly bad to cut the stuff outside.
According to the documentation on all the cement board brands, the hazard is "respirable silica" in the dust, which is a carcinogen and IIRC was the sort of thing that contributed to the old coal miners "Black Lung" disease - essentially it is a size and material of dust that your body can't eliminate so it gets into your lungs and sits. As an irritant it can eventually lead to cancer, or it can just clog things up. I would put it in the class of "a little bit probably won't kill you" but definitely worth doing as much as you can to reduce exposure.
All the boards said to to use the "score and snap" method of cutting if possible. If not, they reccomended wet saws, and / or saws with dust collection built in, and respirators.
When I was just out of HS, I had a job at Budd trailers. I had my own single bay away from the rest of the shop that I had to sand blast the decals off the sides of semi trailers. I was given a regular painters respirator and a hood. On the side of the bags of sand said" Warning, Silica, prolonged exposure without the use of proper resppirator & equipment may cause lung disease". There was an old painter there had emphasyma (spelling) and conitnued to smoke and paint without a mask.
I can tell you a regular painters respirator was not great. It should have been a self contained mask & air tank.
I would pull that hood off and respirator off and have a mouth for of grit, along with the inside of the mask being caked. I didn't care much then, I was young and a lil dumber than I am nowawdays. I smoke alot, and years of breathing roofing chemicals, tar etc, has me thinking more these days. But yes, I still don't wear anything cept maybe some glasses when sawing wood etc. But I try and work smart most of the time, cut in ventilated areas etc.. Anyone can bust my stones as much as you feel like it. I know I am high risk due to my past work. And when I think of it, I try not to contribute to it. Everyone is all gung ho for personal safety protection when cutting logs & etc. I see no difference here.
Ya want ya some silca, just mess with the furnace cement we talk about here. And as for carcinogens in the lungs nothing beats the stuff flying around when you are cleaning a chimney.
I have a respirator and forever forget it in the rush to get stuff done.
Absolutely, I'd tell you to wear the gear, but I understand where you are coming from at the same time - One of my pet gripes is the question of how many injuries are caused by protective gear that gets in the way, causes one to be clumsy, or interferes with vision, etc. I take a sort of middle ground... I wear glasses, and I've had a difficult time finding goggles etc. that don't fog up or make my glasses fog up in a minute or two... Sorry, IMHO if I can't see, I'm not safe... So when I get glasses, I get BIG lenses, and have them made from hard surface polycarb - but I don't do OSHA specs as they weigh to much for comfort. I don't usually wear a respirator when doing wood work, but will when I'm emptying out the ashes in the wood stove. I have gotten more and more into the PPE gear, in part because I've gotten fussier and been able to find stuff that fits better.
The other thing that I feel is a factor is the saying that gets ignored by a lot of people "The dose makes the poison" - There is a lot of difference between an occasional exposure on a small scale, and doing it daily for a living. I am going to suffer a lot less damage from cutting an occasional peice of plywood or even cement board w/o a respirator than a carpenter that is doing the same thing 40 hours a week... However the safety people tend not to make that difference...
Ddes anyone know anything about USG "Fiber Rock" underlayment, i.e., is it suitable for a tile backer under a wood stove? Thanks,
Just looked it up - their Submittal sheet #F102 for it on the
FibeRock web page says it shouldn't be exposed to sustained temps over 125*F so I would say it is NOT suitable.
Durock Cement board IS specifically listed for the application however.
I'm also working on hearth rebuild issues....did some research and found a ceramic product on McMaster (it's all java, I don't know how to link it). Take a look and feedback.
* Temperature Range: -425° to +2300° F
* Heat Flow Rate (K-factor): 1/16" and 1/8" Thick., 0.71 Btu/hr. x in./sq. ft. @ 800° F; 1/4" Thick., 0.57 Btu/hr. x in./sq. ft. @ 800° F
* Density: 6-9 lbs./cu. ft.
* Color: White
This alumina silica ceramic fiber is ideal for both high- and low-temperature applications. If exposed to oil or water, it isn't permanently affected—its thermal and physical properties restore after drying.
Thick. 6" x 100 ft. 12" x 50 ft. 24" x 25 ft. Each
1/16" 93285K22 93285K24 93285K26 $65.13
1/8" 93285K42 93285K44 93285K46 113.63
1/4" 93285K62 93285K64 93285K66 235.39
6" x 20 ft. 12" x 10 ft. 24" x 5 ft.
1/8" 93285K12 93285K15 93285K18 $28.52
Certainly pricier than durock, but the size is enough to do a couplefew layers on a typical size hearth....low K's, for sure. Are the K's listed for 1"? or for the respective thickness? I don't know If they are, you're getting R of 1.40 for the 1/16 and 1/8 (@800F!) and R=1.75 for the 1/4". If it's per inch ratings, they're not good at all (R's of .08 on the 1/16, .16 on the 1/8, .43 on the 1/4) . The problems I see: they don't say specifically that it's fireproof, but alumina-silica should be unless they use an organic binder or something...2300F is a lot to ask for anything organic so I doubt it. It's also hard to say how compressible it is...spacers or high hats would fix that, though.
Just throw up the link...... http://www.mcmaster.com/
and the page
page..3382 (For info)
I use alot of cement board in my trade perhaps way to much....durock is considered the best in the construction trade but remember all of them have styrofoam lil balls in it
Well if Durock uses styrofoam in it's makeup, it's in bits to small to see, and it isn't mentioned in ANY of the documentation that I've seen... The only product of the cement boards that I've looked at which CLEARLY uses styrofoam is Permabase - you can see the beads, they are mentioned in the product documentation, and is the reason why I was told by the Permabase tech support people that it is "Not non-combustible" (love those double negatives :smirk: )
Hardibacker contains wood cellulose fibers - their tech support says that it is NOT reccomended as floor protection, but is fine for NFPA protection walls.
Wonderboard uses fiberglass and seems to have a max reccomended temperature exposure - again, not good for floors, OK for walls
Durock specifically says "NON COMBUSTIBLE, WILL NOT BURN" and has documentation that specifically reccomends it's use in floor protectors as well as NFPA protection walls
As to the McMaster Carr stuff, I haven't looked it up yet, but from the description and GVA's comments, it might be OK or not depending on how compressible it is. The R-value is pretty good - Micore is R-1.1 per half inch, this stuff would be R-0.86 per half inch, which isn't as good, but better than Cement board, and enough to get into the R-1.1 range w/ a layer of Durock, enough for many stoves. The question is whether or not it would offer the structural rigidity and non-compressibility that you'd need for building a floor?
What exactly is the construction going to be for this application? cement board on the studs with stone/masonry/ceramic on it? I'm just curious what the finished product will be.
Having read through this entire discussion, I'm still a bit confused... Since the HardiBacker is non-combustable, can it be used for ember protection all by itself? (I need something temporary to put down over the existing wood floor in order to get my stove installed before I freeze my a$$ off!) Down the road, I will do a full-blown tile hearth for my Scan 61 (which only requires ember and not thermal protection).
I too am a bit confused. Which one would be the best to use for a corner wall install with porcelin tile on it. I would leave a space between the sheetrock and the wallboard the the tile would go on. THanks.
Hardibacker has cellulose fillers and is not the ideal product to use for a hearth, especially if it is the final and only surface. Pure cement board like Durock or Wonderboard are preferred. However, be careful to get the original product. Both companies now also make a next generation version of their cement boards that have styrofoam filler in them.
Either Durock or Wonderboard 1/2" cement board product is good for a wall shield. USG has instructions on their website for making a wall shield using Durock.
If ember protection is all that is needed, I would use hardi backer, I might mix up a little thinset and skim coat the top surface just for looks and to enclose any fiberglass or cellulose fibers. Also if you are not going to remove all the hardwood under the "protector" I would get one of the nonskid rug pads made of the thin foam and place it under the hardi to protect the flooring you are keeping.
The problem with this stuff I found out recently is that without an air space behind it will still transfer to much heat to the materials behind or beneath. I used hat channel on the walls to fir out the cement board and achieve the air space/flow. Most of the codes are written as suggestions thereby leaving the design/builder on the hook if anything happens. I was going to install a class A chimney about a month ago, I called my liability insurance and found out they would not cover me if anything happened. Needless to say, I passed on the job, even though I have installled chimney's for myself with no problems.
As a totally unrelated aside.......
A cheap house construction material in the middle of last century, "fibro" panels were used extensively for exterior & interior wall construction, and roofs, in Australia. As kids we loved to throw pieces of fibro in a fire.....and enjoy the exploding results. :lol:
Little did we know about asbestos :-S
As for cutting...it's a piece of cake with the right equipment
Has anyone checked into the Fiberock Backerboard? It's listed on USG's site as being fire rated.
I'm asking because the local flooring retailer stocks it.
I e-mailed USG about the FibeRock backerboard and this is the reply I recieved:
Our Fiberock Backerboard has an R value of .3 Hr FtÂ² Â°F/Btu, our Durock Cement board has one of .26
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