Dot and dabbing again!

[Woody123]

when dot and dabbing can you just use rapid set adhesive or is it best to use something like drylining addy? Also do you have to skrim the joints or isit ok to just tile straight onto after priming? also do you need to leave any gaps when fixing the boards for movementand im a bit worried about the weight if its just dot and dabbed. doesn't seem strong enough to hold a full wall of tiles if you ask me, however i am uneducated in this so bare with me! any other tips appreciated

 

[Woody123]

sorry for all the questions but how long do you leave it before you can tile onto it?

 

[brummie tiler]

i wouldnt use rapid set personally, Plasterboard adhesive drys out rock solid and done correctly should hold the weight of the majority of tiles. If you are unsure why dont you screw aswell

 

[GazTech]

Dot and dab plasterboard is fine, if you prime the wall to be fixed too. Also rapid set is fine for fixing the boards, but put plenty of dots on the back. Leave plenty of time for the boards to set at the back then tile. Plasterboard will hold 32kg per m2 in weight less adhesive and grout which generally weighs 4kg.....Gaz

 

[Droopy]

Drywall adhesive is easier to use, cheaper, and faster setting than rapid set tile addy.

 

[Woody123]

cheers for the fast respons fellas

 

[GazTech]

Just a word of warning fellas re drywall addy with backerboards. Yesterday I was told a horror story regarding wedi panels dotted with drywall adhesive, 300m2 around a swimming pool...it failed with the weight of tiles (not large format). Hardibacker is fine because its all cement. Always refer to the manufacturer of the boards as to which adhesive they recommend, I would hate something like this to happen to you .....Gaz

 

[DHTiling]

I think most backer boards gaz..actually recommend Tile adhesive don't they mate....?...With them bieng a cement based board and dry wall addy is gypsum based......so you are spot on!!!

 

[Droopy]

Just a word of warning fellas re drywall addy with backerboards. Yesterday I was told a horror story regarding wedi panels dotted with drywall adhesive, 300m2 around a swimming pool...it failed with the weight of tiles (not large format). Hardibacker is fine because its all cement. Always refer to the manufacturer of the boards as to which adhesive they recommend, I would hate something like this to happen to you .....Gaz

Backerboards are normally cement based, so Drywall addy is a definite no no, as that is gypsum based.
The very thing that makes it ideal for fixing plasterboard.

 

[wetdec]

Have a look here Woody 2nd post I got some DotnDab stuff up there


http://www.tilersforums.com/tiling-forum/8538-how-dot-dab.html

tiler

,,

 

[GazTech]

Nice one tiler...gr8 post....Gaz

 

[White Room]

If I was using spf for sticking hardie boards to the wall I would still put a few fixing into the wall as a bit of support IMO.

 

[bj F]

Do not use rapid it is not suitable use plasterboard adhesive.

 

[DHTiling]

Do not use rapid it is not suitable use plasterboard adhesive.

So you would use a gypsum adhesive on a cement based backer board ....?..

 

[tiler burden]

hi mate

use what dave says, nothing else..

1, cut all you boards first ready to fix
2. mix you addy in a bucket, it must be thick enough to hang on to your trowel when turned upside down.
3. dab on the wall every 12 in as you say, so if its a 8x4 board you want 5 along the top and 9 up the side and in corresponding lines vertically.
4. use a trowel or the rear of a bucket trowel to slap the dabs on, they need to be around 25mm thick minand the boards will press in about 12.5mm allowing for any cables to go down the back etc.
5. tap the board with a 6ft straight edge/level at either side, then when you have fixed 2 boards side by side, put your straight edge across the boards horizontally, to ensure they dont dip in , in the middle. do this till you reach the end of the wall. you can put a square in the corners aswell to make sure everything is spot on
6. keep the boards off the floor by place 2 off cuts of plaster boards under the 8x4 or 6x3 boards (stops water penetration/damp)
7. finally, ensure there is a full dab of adhesive around all sockets and switches to ensure pressure testing.
8, finally finally...if the walls are really old and dusty, brush down and wet, or even seal with water and pva at around 4to1 ratio.
if its newish block/brick work , then just get em up


hope this helps

ed

 

[tiler burden]

i wrote the above post back in february for tysfoot.

use only drywall adhesive for dotting and dabbing plasterboards, ;0)

 

[Varley]

hi mate

use what dave says, nothing else..

1, cut all you boards first ready to fix
2. mix you addy in a bucket, it must be thick enough to hang on to your trowel when turned upside down.
3. dab on the wall every 12 in as you say, so if its a 8x4 board you want 5 along the top and 9 up the side and in corresponding lines vertically.
4. use a trowel or the rear of a bucket trowel to slap the dabs on, they need to be around 25mm thick minand the boards will press in about 12.5mm allowing for any cables to go down the back etc.
5. tap the board with a 6ft straight edge/level at either side, then when you have fixed 2 boards side by side, put your straight edge across the boards horizontally, to ensure they dont dip in , in the middle. do this till you reach the end of the wall. you can put a square in the corners aswell to make sure everything is spot on
6. keep the boards off the floor by place 2 off cuts of plaster boards under the 8x4 or 6x3 boards (stops water penetration/damp)
7. finally, ensure there is a full dab of adhesive around all sockets and switches to ensure pressure testing.
8, finally finally...if the walls are really old and dusty, brush down and wet, or even seal with water and pva at around 4to1 ratio.
if its newish block/brick work , then just get em up


hope this helps

ed

Great post Tiler Burden, thanks for this cool little tutorial

 

[Woody123]

Some very useful post's in there fellas, thanks for sharing all our knowledge.
yet again it has proved invaluable. If it wasn't for all the knowledge on here i probably would even attempt to do something i have never tried before but when you ask and do a little research then it doesn't seem so scary.
Cheers again

Chris

 

[Woody123]

Tiler,

I have just read that info that you put up and it says that surface to be dot and dabbed should be sound and flat. the surface i am d and d is a rough gray surface that is on top of breeze block is that ok as long as i prime? And also i am re-boarding the window reveals as they are badly damaged with big chunks of plaster out of them is that still ok were talking maybe an inch and a half chunks at the side of the window

 

[tiler burden]

hi woody,
not sure if you are directing that question at me or wetdec bit i'll answer it anyway.

you say that the wall is breezeblock covered in a rough grey surface. this rough grey surface is likely to be 'hardwall'. hardwall is a high suction backing coat to be used on breezeblock. it has a higher thermal value than sand and cement and it looks a little bit like carlie bonding, so you will easily be able to recognize it next to sand and cement.

so, if it is hardwall, then dont prime it!!!!!, just give it a wet down will a water brush or a roller or sprayer etc. and then apply your dabs and start boarding.

if by some chance the wall is coated in carlite bonding, then just do the same. wet down and apply. carlite bonding has little chipping of vermiculite in it, so it is easy to determine the differenc between it and hardwall. just to add, DONT use carlite bonding on breezeblock. it is a LOW suction backing coat and it should be used on surfaces such as skimmed walls, concrete and dense brick work such as engineering bricks.

as for the window reveals, yes it ok to go on thick. to give it a tiling term, i always 'solid bed' the reveals. in other words i dont dab them on, slap on drywall adhesive all the way down the plaster board or wall and then set them on solid.

hope this helps, if not ask away

ed

 

[Woody123]

Managed to get all the boards up fellas just wondering how long i should leave it before i tile? Would you leave 24 hours to be sure or is that overkill? the plasterboard adhesive instructions says it intially sets between 90-180 mins depending on thickness of dabs.......also can i prime straight away aswell? or do i have to wait till the adehsive sets to prime?

 

[wetdec]

Sorry Woody m8 missed you TB put you right .......cool


@ TB ... cheers


If your not rushing m8 then just leave it dry a while just like Hydraulic adhesive it sets but takes a while to dry properly

tiler

..

 

[Woody123]

Cheers for getting back to me mate, anyway i ended up just leaving it just to be on the safe side cos there biggish tiles that are to be fixed so better to be safe than sorry. Im all set to start tiling 2morrow night. Cheers for the help everyone

 

[smurf21]

instead of d&d why not screw battons straight to wall and fix plasterboard straight to batton takes awhile longer but you can fix tiles straightaway ( no drying time just a thought} also easier to feed cables and pipes behind.

 

[White Room]

If the walls are flat it would work, If the wall are all over the place you might need packers behind the batons to make them flat, Or dot and dab