osb/cement-board countertop..for tiling

[ekon]

planning to use 600X600 tiles on 70+ cm-deep counter-top

22mm osb (already in place)..now have to fix the cement backer-board before tiling.

Q1 do I need to prime the osb before applying the adhesive (SPF/thin set mix) and screwing down the backer-board onto it ? if so what is best product to prime the osb with?

Q2. what do people reckon are the best makes of SPF adhesive?

Q3. Once the backer board is on and fixed/set... is there anything else to do to the backer-board before applying the tile-adhesive to it ...wet the board with a sponge?...any primer needed?

Q4. what sort/brand of tile-adhesive is best for bedding big 600mm square tiles? (high-gloss floor tiles) onto the backer board?

thanks

 

[tpt]

depending on the brand of backer board you can use no-more-nails\gripfill\megas strength grab adhesive (the solvented type), you use this in concentric circles and also screw the board.
i'd suggest this is better because no thin set addy is going to like sticking to OSB.

once your backer board is in place, you'll need a flexi adhesive. if theres much movement then despite your backer board you'll still need an S2 addy such as granfix ultimate flex. if theres very little movement and the WT is well supported you could use an s1 instead, but theres not much difference in cost.

prime the backer board with SBR (again, depends on brand).

if your fixing cuts to the front of the WT, then you may have difficulty making them stay in place.

Dont forget - use an epoxy grout in a food prep area.

If your going down this route to get a cheap granite worktop it may be false economy - have a look at a company called diapol.

 

[ekon]

>thanks tpt..very helpful.

the board I have bought was from my local (11 miles away!..we live in the sticks) builder's merchants..they only stock "Mineret"..sadly can't find much at all on the net about this brand...have you ever seen it? ...had the advantage that they'd cut quite a few one-third sheets i.e. 1200x800 so I could get them in the hatchback.

 

[tpt]

its not a brand i'm familiar with - might be best to call the manufacturer?

 

[ekon]

I googled "Mineret board" yesterday..just got 2 "hits" neither of which was any use at all..both American websites!?

I will just do as you advise ..gripfill between osb and backer board and an S2 addy for the tiles..thanks again for helping

 

[tpt]

this is the guide for the brand we sell
http://www.nomoreply.net/overboarding TIMBER.htm

 

[ekon]

thanks for the link...

..have just read the "wetroom" bit of that guide..would it be worth doing 2 coats of SBR on the backer board adjacent to the sink?

I have already done 2 coats of weatherproof pva (not the one that re-activates with water after drying) around the cut out in the osb and have smeared some just now round where the cut-out in the backer board meets the osb ..within a mm or two matching shape at worst.

 

[tpt]

honestly - no not really. the backer board wont distort of be affected by water, the OSB will, i'd be inclined to silicone the joints\gaps in the backerboard near the sink.

 

[tictic]

Question....

Why did you go with osb?

IMO your starting off all wrong in using this....

But if already set...THEN...

As tpt as told you.....


Epoxy grout...even around the edge off w/top and wall...