DIY GRP tanking

[virgilns]

Hello all...new here and thought it a good place to get some advice from the experts!

Just about to make a 3 wall tiled shower enclosure with two brick and plaster walls and one plasterboard wall (plaster board will be replaced as old tiles in the previous enclosure let water in and disolved the board!

My question is, there seems to be several options of tanking the walls/floor.

I've seen GRP tanking and having worked with fibregalss before thought this might be an ideal solution. Is it as straight forward as just fibreglassing the walls and floor with mat and tiling straight over the top, or are the flexible paint on/matting solutions 'a must'?? The wet room/cubicle will be about just under half the 2m by 1.2m room...so about 90cmm by 1.2m

Also can I use underfloor heating on the floor and WALL with porcelin wall tiles (600*300) with either Bal tanking, Homelux wall/floor matt or GRP tanking?

Thanks in advance,

Virgil.

 

[Richard C]

Just about to make a 3 wall tiled shower enclosure with two brick and plaster walls and one plasterboard wall (plaster board will be replaced as old tiles in the previous enclosure let water in and disolved the board!

Use waterproof tile backer board where the plaster board was & tile straight over that, just fill & tape the joints; you can also tile straight onto the original brick & plaster walls, depending on tile weight; no real need to tank unless you’re constructing a wet room.

My question is, there seems to be several options of tanking the walls/floor.

Why do you want to tank the floor? Do you have a shower tray or are you constructing a wet room floor?

I've seen GRP tanking and having worked with fibregalss before thought this might be an ideal solution. Is it as straight forward as just fibreglassing the walls and floor with mat and tiling straight over the top, or are the flexible paint on/matting solutions 'a must'?? The wet room/cubicle will be about just under half the 2m by 1.2m room...so about 90cmm by 1.2m

Not entirely sure if your actually proposing GRP matting as a tanking medium but I’ve also worked in the glass fibre industry. I would forget GRP, it’s overkill & will far more difficult/costly to apply than a proprietary tank membrane or liquid membrane such as WP1 or Dunlop.

Also can I use underfloor heating on the floor and WALL

Why on earth would you want to put UFH in the walls , I see absolutely no benefit in that at all! If it’s electric UFH you’re intending, bathrooms & kitchens are classed as special locations & it’s not really a DIY job. You should either use a Part P registered spark who will install, test & supply a compliance certificate or, if really intent on DIY, submit a Building Notice to your LABC but not worth the hassle IMO.

with porcelin wall tiles (600*300)

Thems big/heavy tiles & you must use a cement powder adhesive suitable for porc tiles, not tub mix; it must also be flexible over the boards. Another potential problem you have is that you can only hang a maximum of 20 kq/sqm (including 3-4 kg for the adhesive/grout) onto a plastered surface, you may need to board out or reconsider the tile size/weight; what weight are your tiles?

with either Bal tanking, Homelux wall/floor matt or GRP tanking?

As already said, you don’t really need to tank backer boards or conventional plaster/screed walls unless your forming a wet room. Forget the GRP.

Take some time out to read the Tiling Forum sticky & archive posts, it may prevent you making some potentially expensive mistakes; come back if you have more questions.

 

[virgilns]

Thanks for the response.

The reason for tanking the floor is I want a 'wetroom floor' in the shower area so I don't need a tray (the 'cubicle' will be an odd shape...80cm one end 100cm the other)

The reason I want the heated wall is that it feels so nice when having a shower not to have a cold wall next to you (I spend a lot of time in hotels and some of them have heated walls, so know how nice it is!)

Just weighed a tile - 3.5kg each, so about 20kg/sqm. What's the issue with tiling on a platered wall heavier than that??

Had a good look throught sticky - very useful info, but I definately need to tank, and would love to have under floor heating (even if not in the walls ) so sounds like a bal tanking rubber stuff??

 

[Richard C]

The reason for tanking the floor is I want a 'wetroom floor' in the shower area so I don't need a tray (the 'cubicle' will be an odd shape...80cm one end 100cm the other)

That changes things rather but a wet room tray former + boards will be far easier than trying to make your own; how exactly do you intend to form the tray & wet room floor?

The reason I want the heated wall is that it feels so nice when having a shower not to have a cold wall next to you (I spend a lot of time in hotels and some of them have heated walls, so know how nice it is!)

I won’t go into why but I’ve spent much of my life traveling & living in hotels. I’ve stayed in some of the best hotels in the world but I don’t recall any of them having heated walls! Nice in Iceland this time of year maybe, but I’ve been there & they didn't have it but with tripple glazing & geothermal heating, it's not necessary. Here in the UK, even with the current cold snap, your just wasting your time & money cos the "warm up" time will be excessive enough to render it pointless unless you leave it permanently on & that won't exactly be cheap to run.

Just weighed a tile - 3.5kg each, so about 20kg/sqm. What's the issue with tiling on a platered wall heavier than that??

But did you add on the 3-4kg for addy & grout? There will be some margin because BG need to cover their ass but exceed the weight limit & there is a very real risk the tiles will fall off taking the plaster with them. Don’t take my word for it visit British Gypsum website & read their recommendations;
http://www.british-gypsum.com/pdf/SB07_Tiling_02.pdf

Had a good look throught sticky - very useful info, but I definately need to tank, and would love to have under floor heating (even if not in the walls ) so sounds like a bal tanking rubber stuff??

For a wet room, personally, I think you would be better using a physical membrane system rather than liquid membrane; now have a read through the archive posts for good measure.

 

[virgilns]

Thanks again for the replies, Richard and hope my post the other night didn't come across rude, was just poting in a hurry. Re-read my "what's teh issue with tiling on plaster" and thought "jeez, that sounds stroppy!" sorry if it came across like that!

So 20kg is the limit for plaster walls. I guess plaster is not a great substrate for tiling.

Will think about ripping the plaster off and either flat (not smooth) render or board it as close as poss to wall. Room is small enough already so don't want to lose more space with battening board etc...

For the floor I was going to remove floor boards and use 2x 18mm marine ply screewed and glued. One layer on 2x4 'battening' level with the tops of the joists, the next on top leve with the existing floorboards. I've done this in the downstairs loo with underfloor heating and perfect! Maybe a bit belt and braces but can't be too 'solid' as far as I can tell.

for the former, I was going to have a 2" upstand (floor tiled both side to blend in a full width sliding door on top. Will taper the floor down to nothing providing the drain gradient.

The budget is fairly tight but I want a proper job done, and got a week with a weekend either side to get it done so needs to be doable in the time frame as well!

Going to fit a shower pump and wall mounted loo...so going to be good fun!

 

[Richard C]

hope my post the other night didn't come across rude, was just poting in a hurry. Re-read my "what's teh issue with tiling on plaster" and thought "jeez, that sounds stroppy!" sorry if it came across like that!

Not at all, no problem . My style tends to be a little direct which folks often take the wrong way.

So 20kg is the limit for plaster walls. I guess plaster is not a great substrate for tiling.

With the piddly little tiles folks used to use on walls there was no real problem, it’s only since large format tiles became fashionable that you need to be careful with weights & the adhesive you use; tile backer boards are usually the answer.

Will think about ripping the plaster off and either flat (not smooth) render or board it as close as poss to wall. Room is small enough already so don't want to lose more space with battening board etc...

Probably far easier to fix waterproof tile backer boards & tile directly onto that. If you use a conventional render base, it can take up to 4 weeks to dry before you can tile. If it’s just repairs, you can use a cement based tile addy which will accept tiles after 24 hours or use a quick set render but it’s rather expensive.

For the floor I was going to remove floor boards and use 2x 18mm marine ply screewed and glued. One layer on 2x4 'battening' level with the tops of the joists, the next on top leve with the existing floorboards. I've done this in the downstairs loo with underfloor heating and perfect! Maybe a bit belt and braces but can't be too 'solid' as far as I can tell.

Firstly you don’t need marine ply, WBP is just as good & cheaper. It’s made using the same waterproof adhesive on the veneers but doesn’t have expensive finish veneers on the outside which you don’t need anyway. Make sure you seal the underside & edges with an SBR primer.

A little confused; so are you going to cut strips of 18mm ply & set them between the joists & then cover the whole lot with another layer of 18mm ply?

for the former, I was going to have a 2" upstand (floor tiled both side to blend in a full width sliding door on top. Will taper the floor down to nothing providing the drain gradient.

You may do better to look at a preformed wet room tray system; all you need then is to build the rest of the floor around it.

Going to fit a shower pump and wall mounted loo...so going to be good fun!

Make sure you research that one as well; design the circuit correctly & get the correct pump or you may be back on here asking why the shower doesn’t work!