Priming Plywood

[pendleh]

Hi Guys

Recently been reading posts about plying out which recommends priming the back and sides of the plywood. Can anyone tell me why - thanks.

Best Wishes

Howard

[doug boardley]

Hi Howard, you prime the back and the sides to stop moisture seeping through from the edges and the bottom of the ply. If this happens it can delaminate your ply and consequently cause your tiling to fail,tent,unbond etc!

[faithhealer]

never primed the back of plywood before but with Dougs comment in mind I'm going to start.

[pendleh]

Thanks Doug

In america they tend to use cement board instead of ply what are your thoughts on this?

Howard

[faithhealer]

Usually I give the customer a choice and it's always the price that makes them go for plywood!

[grumpygrouter]

Hi Guys

Recently been reading posts about plying out which recommends priming the back and sides of the plywood. Can anyone tell me why - thanks.

Best Wishes

Howard

Lets not confuse the phrase "priming" with "sealing". BAL recommend SEALING the back and edges of ply with BAL BOND SBR. It just so happens that this product can also be used as a primer. Ardex on the other hand recommend using polyurethane varnish for sealing the back and edges. Don't think this can be used as a primer though.........priming as far as I am away is preparing something to accept another coating/finish on the top.

As always, I am happy to be corrected if peeps think otherwise.

[brian c]

Just a thought for everyone,just check the spec with the nmanufacturer of the adhesive that you are using as some have different spec ie BAL sides and underside,whereas others just say prime the face of ply.

[bathroomboy]

I'm not advising anyone to do this but I took up my own bathroom floor on Friday after it,s been down for 15 yrs and what a job it was, the tiles were so well bonded a 6x4 piece came up after a lot of grunting and groaning from 2 of us and the tiles were intact on the ply.
I remember screwing it down at 150m/m centres and priming it with neat pva on it's face nothing on the back (I know before anyone jumps in I now use acrilic primer in accordance with the manufacturor) I just hope all the floors I am doing now are bonded as well.
As far as I can remember the adhesive I used was evostik tile on wood, not something I would use now, but it did the job well as the tiles were really difficult to remove even with a large sds and armeg tile removing bit, gave up in the end and reverted to levering the ply up.

[brian c]

sounds like you have learned a fair bit over the last 15 years BB...LOL.....How times and methods change eh.I kNOW OF TILERS WHO STILL STICK TO THE PVA AND WONT BE TOLD ANY DIFFERENTLY BY ME OR ANYONE ELSE....STUBBORN AND IMO STUPID ,UNLIKE YOURSELF WHO SEEMS TO BE ADAPTING WITH CHANGE...WELL DONE M8.

[bathroomboy]

Thanks Brian, just knocked a brick wall out to make the bathroom bigger, the floors coming up and 18m/m plys going down and Ditras going in as well, something Iv'e never used but like you said, got to adapt, good to try on my own job first. Cheers mate.

[Dave]

Just for you BB .. A video on installing ditra..


http://uk.youtube.com/watch?v=f6FyWs...ext=1&index=62