Installation of Durock to OSB
PhilandKathleen
| Posted in Construction Techniques on
We are building a seasonal home in Northern Michigan (therefore it will be subject to lots of freezing/thawing). Currently we are putting ceramic tile in our mud room and bathroom. We have 3/4 OSB and want to attach Durock to it.
What is the best adhesive to use? Durock home page says to use latex fortified mortar. We can only find latex MODified mortar.
What about polyblend mortars?
Considering the amount of freezing and thawing…should we mix the thin set (that will be used to laminate the OSB to Durock) with acrylic (Hydroment Multi Purpose 425)? Or just use water?
What is best to use for taping the joints?
Replies
Phil and Kathleen: I have always utilized polyblend thinset to bond backer board to plywood or OSB subfloors. Use the same thinset for taping the joints, and use the tape that is designed for this purpose. The tape is a bit heavier than standar drywall mesh tape and should be available where you get your tile supplies. You can use the special screws that are available, but expensive, but I've had excellent luck using galvanized roofing nails. The nails seem like overkill with the thinset, but better safe than sorry.
I have mixed with just water in cool climates and had no problems. Some fortifiers are not compatible with certain thinsets or grouts, so be careful. Make sure your tiles are frost proof if they'll be subject to freezing temps.
Good luck.
The most important thing is to carefully read the manufacturer's instructions. Different types of backerboard are attached in different ways, and installation methods can be crucial to the product's performance (Dens-shield comes to mind). Same goes for the thinset- the mfg should tell you what it is and is not compatible with.
IMO, latex fortified and latex modified mean the same thing. Modified thinsets either come as a dry mix with the polymer already added (just mix with water), or you may use a latex additive with unmodified thinset. Don't use additional additives with a modified thinset. Make sure that whatever thinset you do purchase is compatible with plywood, as not all are. I agree that especially in your climate you should use a premium, polymer-modified thinset for both the backerboard and setting the tiles.
-Andy