I would very much appreciate any advice on a few questions reference flooring in 2 bathrooms (6sqm in total) and a kitchen (11sqm):-

1) Do I use 18mm or 12mm WBP floorgrade ply when over laying weyroc? All of the big companies tend to suggest 15mm but I am struggling to find it. Most exerienced tilers tend to state 12mm will suffice. I am avoiding the direct onto Weyroc route as most people seem to be against this as an option.

2) How sound does the existing weyroc have to be if I am overlaying with ply. For example the kitchen floor boards seem to be a bit bouncy. Will the ply sort this out or should I be taking it up and replacing the area to be tiled with 18mm? If the latter then has anyone got any tips as to how this is best done?

3) What is the point of priming the back and sides of the ply if the grout is not waterproof? Surely more water will come from above than below? Should the top of the ply also be primed to ensure no ingress from above? I am planning to apply a grout seal and the tiles are ceramic.

4) I have been quoted approx. £45 for a 5lt BAL SBR, this seems very expensive compared to Everbuild SBR and Nicobond Acrylic. Are all suitable? i.e. do all makes of SBR do the same? Also if I should be priming the top of the ply then will all of these be OK?

5) I have already got in the garage some BAL APD - Could I use this?

6) I believe that in the ideal world the ply should be allowed to acclimatise 48hrs in advance of laying, is this really neccesary?

7) The sheets of 8*4 ply will obviously be quite difficult to handle so am I better to get the timber yard to cut into more manageable chunks or are extra joins to be avoiding at all costs?

I am planning to use Bal supercover rapid flex adhesive and superflex wide joint for the grout.

Sorry it's a long email but these are my first jobs and it's almost 9 months since I finished my training and I really want to start as I mean to go on by doing a top quality job so any help would be very much appreciated.

Kind Regards,
Mark.

Originally Posted by sparkypenguin

I would very much appreciate any advice on a few questions reference flooring in 2 bathrooms (6sqm in total) and a kitchen (11sqm):-

1) Do I use 18mm or 12mm WBP floorgrade ply when over laying weyroc? All of the big companies tend to suggest 15mm but I am struggling to find it. Most exerienced tilers tend to state 12mm will suffice. I am avoiding the direct onto Weyroc route as most people seem to be against this as an option. Is there any height issues?

2) How sound does the existing weyroc have to be if I am overlaying with ply. For example the kitchen floor boards seem to be a bit bouncy. Will the ply sort this out or should I be taking it up and replacing the area to be tiled with 18mm? If the latter then has anyone got any tips as to how this is best done? How bouncy is bouncy, its hard for us to tell. But if you think it is too bouncy then it needs strengthening with extra noggins.

3) What is the point of priming the back and sides of the ply if the grout is not waterproof? Surely more water will come from above than below? Should the top of the ply also be primed to ensure no ingress from above? I am planning to apply a grout seal and the tiles are ceramic. Follow the adhesive manufactureres instructructions, BAL wil say no to priming the face, Only back and edges.

4) I have been quoted approx. £45 for a 5lt BAL SBR, this seems very expensive compared to Everbuild SBR and Nicobond Acrylic. Are all suitable? i.e. do all makes of SBR do the same? Also if I should be priming the top of the ply then will all of these be OK?
i would look at other stockist of primers, very expensive but then thats BAL for you.

5) I have already got in the garage some BAL APD - Could I use this? Again follow BALs instructions

6) I believe that in the ideal world the ply should be allowed to acclimatise 48hrs in advance of laying, is this really neccesary? Personally i never have, if it were wet then of course but then i wouldnt buy wet ply.

7) The sheets of 8*4 ply will obviously be quite difficult to handle so am I better to get the timber yard to cut into more manageable chunks or are extra joins to be avoiding at all costs? Get it delivered to site, most companies do delivery.

I am planning to use Bal supercover rapid flex adhesive and superflex wide joint for the grout.

Sorry it's a long email but these are my first jobs and it's almost 9 months since I finished my training and I really want to start as I mean to go on by doing a top quality job so any help would be very much appreciated.

Kind Regards,
Mark.

I hope that was of some help.

2) How sound does the existing weyroc have to be if I am overlaying with ply. For example the kitchen floor boards seem to be a bit bouncy. Will the ply sort this out or should I be taking it up and replacing the area to be tiled with 18mm? If the latter then has anyone got any tips as to how this is best done?

Sounds like a floating floor....are there any fixings in the boards or just T&G joints..?

Sir Ramic / Dave,

Thanks very much for your replies .

Here are some more questions relating to some of the above points which I am hoping that someone will be able to help with.
I have kept the point numbers the same to help!

1) There are no real height issues apart from the fact that it will create a difference in height between 2 rooms, however the customer is considering getting wood laid in the other room so I think that either 12 or 18mm would be fine cosmetically. I am erring on the 18mm due to the "bounce". If I could find 15mm I would probably use that but I cannot seem to find anywhere that sells it in the Sunderland / Durham area. Any contacts / £ guidance would be helpful.

2) I am not sure how to discribe how bouncy the floor is and the floor is actually Weyroc, not floor boards as I described above (novice description error!). And they are securred with nails. Could it still be a floating floor and if so what are the consequences? the bounce tends to be in the middle of the boards. Is this fairly normal with Weyroc?

3) I appreciate the advice reference priming of back and sides and following the manufacturers instructions however I would be interested in an explantion as to why the backs and sides and not the top should be primed. I like to understand why I am doing something and I would have thought that more moisture / water is likely to come from above. If the floor gets wet then surely the water will go down through the grout and adhesive and into the unprimed ply. If the backs and sides are primed will the water not get trapped within the ply? Maybe the priming of the ply is more to do with creating a water resistant barrier so that the moisture does not continue down into the Weyroc? Any thoughts?

7) When I am laying the ply over the existing Weyroc do the the edges of the ply have to lie on a noggin / beam? And how close to the edges of the room / other obstacles do I need to get the ply, i.e. how accurate does the ply have to be cut.
I was going to aim to leave a 1mm gap as a minimum for expansion between boards and at the edges, and a maximum gap of 5mm around obstacles. However if this is too accurate then I would like to know for obvious reasons. Do these gaps need filling with a flexi filler or will the flexi adhesive do the job as I am laying the tiles?

8) Also as I have worked most of my life in an office any tips on how to transfer the room shape / size / obstacles onto the ply for cutting would be appreciated, I know how to do it for a tile and for Karndean flooring but I don't think that these principles will work for a sheet of 8 * 4!

Kind Regards,
Mark.