Bonding Steel Panels to Cementitious Backerboard
We need to adhere some fairly thin-gauge steel panels to cementitious backerboard as cladding surrounding a gas fireplace. Anyone have any recommendations for a good product to use as an adhesive here? I’m leaning towards an epoxy grout, like Laticrete’s Latapoxy 300 or 310, but could also see using more of a traditional epoxy, something like West System’s G/Flex or Six10. I think it’s important that there be some flex to the bond and that it’s able to withstand some temperature.
Can any of you out there speak to this? Many thanks in advance!
Replies
The problem is, of course, that, particularly with the temperature variations this will be facing, it's important that whatever you use remain plastic. I suspect that most epoxies get too hard for this duty. But you also need to withstand the temperature (and most adhesives are either softened by high temperatures or hardened by them).
Depending on the peak temperature expected I'd be strongly tempted to use fasteners.
Don't
Instead, let the panels float free in a frame made of light gauge, small aluminum channel - available at your home center. Attache the channel to the backerboard with small machine screws, with nuts and washers behind. Drill the cement board using the spade-shaped 'glass drilling' bits.
Letting the metal float will let the ripples in it absorb any expansion as it heats up.
Yep, Those Two Prior Posts...
... pretty much summed up the difficulties in your suggested approach.
Dissimmilar materials react differently when exposed to heat. Metal against cement backer will want to expand. Add radiant heat from a gas (or wood) fire & most epoxies will tend to soften. Heat is frequently recommended for breaking an epoxy bond on materials that can withstand it.
If you can't or don't want to work with a fabricated channel arrangement to keep the edges captive, you may want to look into some of the high temperature silicone adhesives that are out there. Those may have an application in your case where other exotic adhesives would tend to fail over time.Silicones remain simewhat flexible, permitting metal to move without stressing the adhesive bond.
Silicone caulking will handle the heat and let the panel expand and contract - use the 100% silicone stuff and it's good for close to 300 degrees
Yes, but...
IdahoDon wrote:Silicone caulking will handle the heat and let the panel expand and contract - use the 100% silicone stuff and it's good for close to 300 degrees
I'd agree if those panels aren't going to be too close to the flames, otherwise radiant heating could raise their temperature well above 300°F. That's why I suggested the high-temp stuff, usually good upwards of 500°F depending on product recommendations.