dot and dabbing plasterboard ?

[terry the tiler]

hi , got a plaster board dot and dabing job to do as the walls are ridiculous and wondering if you lot take it back to the brickwork before boarding walls ? and whats the weight limit on this using drywall addy to fix boards ? thanks !

[Scott]

Its only as strong as the material you are bonding it to. I use mechanical fixings as well as D&D

[Alan.P]

Depends really, as Scott says, depends on the background.

[steve187]

What sort of tiles are you using, dry lining can take more weight unskimmed.

[widler]

id take it to the brick/block,much much stronger bond,(make sure you damp down brick/block work 1st).dry wall sticks like stuff to a blanket,if done right,and yes don't bother skimming it

[TF Ed]

hope this info ive listed helps a bit with your question..

i would fix direct to the block/brickwork. make sure all dust is brushed off and dampen if the wall has a high suction.
if the wall have a very low suction, then give it a coat of sbr, not pva for tiling.

. No priming required unless the boards are particularly dusty, warm /dried out or old.
. Maximum weight ratio is 32kg/per m2
. Skimmed plasterboard weight ratio is reduced to 20kg/per m2
. Foil back plasterboards must be mechanically fixed to timber or metal frame work.
. 12.5mm boards fixed to timber should be fixed with 38mm screws; metal should have 25mm screws.
. Water sensitive, suffers from mould ingress due to paper lining but has good ‘fire resistance’.
. There are 3 board thickness’s 9.5mm, 12.5mm and 15mm
. Board sizes are: 1200mm x 240, 2400mm x 120mm and 3000mm x 1200mm.
. Fix boards with the ivory side facing you, not the darker side.
. When tiling to a ‘dot and dabbed wall’ then the boards must be left for 7 days to cure prior to tiling.
. If fixing stone or thick porcelain to a dot and dabbed wall, add an extra horizontal bed of adhesive at the mid way point of the plasterboard for extra strength
. Useful technical info ‘The White book’ on the British gypsum website.
. Knauf also manufacture plaster boards.

Installation...

There are 2 methods of fixing plasterboards

1. Dot & Dab – boards are cut to size and adhesive is mixed ready to dab on the walls. Dabs are placed every 300mm across and down the boards using a plasters/dabbing trowel.
There MUST be a full line of adhesive around the perimeter of the wall inc electrical boxes. Dabs are compressed to around 10mm thick and a 10mm air void should be maintained behind the boards for fitting cables etc.
2. Mechanical Fixing – boards are screwed to timber or metal wall partitioning at 300mm centres on walls, 230mm on ceilings. (nails are @ 150mm centres)
3. Screws for metal = 25mm screws for timber = 38mm

GYPROC GREEN BOARD – water resistant plaster board

. Water resistant ‘green’ paper faced plasterboard. (green both sides!)
. There are 2 board thickness’s 12mm and 15mm
. 12mm thick boards are: 1200mm x 2400mm
. 15mm thick boards are: 1200mm x 2400mm, 2400x 1200mm and 3000mm, x 1200mm
. Maximum weight ratio is 32kg/ per m2.
. Boards can be ‘feather edged’ OR ‘flat edged’ and it is installed exactly like plasterboard.
. Boards can be skimmed but require an acrylic primer ie thistle bond-it, to ensure a stable bond.
. Tile on the ‘light green’ side of the boards.
. No gap is required between the boards, just lightly press together and tape the joints with fiber tape.

Installation...
Fix in the same way as plaster board!

[paul78]

good post there aston

[whitebeam]

That should be stickied, great info.

[terry the tiler]

sorted !! thaks for that

[terry the tiler]

just ceramic 12 by 8. just wanted to no if i could get away with dabbing boards over existing very uneven plaster! had the old tiles removed and the walls are left with old adhesive etc. think it would be easyer to overboard than scrapping old addy of and trying to level walls prior to tiling .