am about to tank my wet room but will be priming the plasterboard and plywood floor with mapei primer g before using mapei flexible adhesive. what ratios shall i use for plasterboard and floor?

Originally Posted by roberto1490

am about to tank my wet room but will be priming the plasterboard and plywood floor with mapei primer g before using mapei flexible adhesive. what ratios shall i use for plasterboard and floor?

Do you mean how much primer?

If so use it neat

yeah mate. so it doesn't need diluting? shall i use it neat on both the walls and floor? read conflicting advice as to whether primer g can be used on plywood. is it ok?

Originally Posted by roberto1490

yeah mate. so it doesn't need diluting? shall i use it neat on both the walls and floor? read conflicting advice as to whether primer g can be used on plywood. is it ok?

Yeah neat on the walls.

Is the floor being tanked? If not, then you wont need to use a primer on the face (bit your tiling) of the ply.

If the ply isnt already down then seal the back and the edges of the ply with neat primer. If its already down just make sure its dust fee and tile away with a suitable adhesive.

Im pretty sure that Primer G shouldnt be watered down? Might be wrong though.

thanks for the advice. floors down but i didn't prime underside. floor will be tanked after priming using durabase wp. the bottom half of my walls are new plasterboard and the top is the old plasterboard which i think has been lined and painted. will the paint have to be sanded down before priming?

Primer G can be diluted depending on the use.. i'e dust proofing floors etc..

Primer G is not suitable for priming ply back or sides.. it needs to be an SBR type primer ..... but as burnsey stated above if tanking with a solution kit then the surfaces do need priming.. the instructions are always on the product you use..

cheers dave. i think i'll use it diluted 1:2 on the floor and neat on the walls so it goes a bit further.

You won't need to prime when using the durabase wp..

no? why's that out of interest. does the ply not need sealing? will the adhesive stick to the substrate ok? sorry for all the questions, i'm new to diy

Most flexible adhesives will adhere directly to clean ply... no need to prime.

Always check the preparation instructions on the bag.

sweet, that's saved me a job then.

One of the main reason we use an acrylic primer on walls is that it stops the gypsum in the plaster reacting with the cement in the adhesive (bagged adhesive) which can cause the tiles to de-bond. Is it called ettrignite Dave?

Tile adhesive bonds very to ply so no point in priming as technically wont do anything.

Cheers for the input on Prmer G Dave . Not a big Mapei user really, not that readily available to me. always love their gear though

Here are is a PDF with instructions and data on Primer G

Primer G

Someone posted the link on the forum ages ago, not sure who but I always keep things like this as they come in handy

Ettringite it is....

Most acrylic primers can be diluted for dust proofing....

After many years as a bal user.. mapei was an eye opener forme.. love the stuff... so much smoother and not as expensive..

I use a lot of Weber and PR360 primer which cant be diluted. Ive used Primer G before a few times but only for priming plaster so never diluted