Wedi sealant on hardie backer boards?

[Curiousv]

Can we use wedi sealant on hardie boards or it can be used only on wedi boards?

 

[ss3964spd]

What's the application? If you're considering using the Wedi sealant instead of taping and mudding the Hardie Board joints then no.

 

[Sponsor]

 

[Jadnashua]

HardieBacker boards, similar to all cement boards, are NOT waterproof, but are not damaged by being wetted. There are actually two classes of CBU (cement backer unit): fiber-reinforced (of which Hardie is one) and 'plain', primarily cement. The fibers in Hardie are cellulose (wood fibers), so the installation and restrictions does vary between it and a 'plain' cbu. THe fibers make the Hardie a bit harder and stiffer, but because all CBUs can wick moisture, that's a problem for a fiber-cement product...it must be installed a bit differently where it could end up sitting in water...that won't work reliably.

So, adding a sealant to the seams probably doesn't do much except empty your wallet some. Wedi sealant and panels are both waterproof, so adding the sealant to penetrations and seams makes the whole thing waterproof. Bit difference between water resistant and waterproof. CBU is water resistant and needs significant other treatment to become waterproof.