PLASTERBOARD UNDER KITCHEN TILES & DRYLINING OUTSIDE WAL Ask your questions and find answers on many subjects relating to plastering and dry lining

[Yorkshireshrek]

A neighbour in the building trade has helped me with my new kitchen. He has bricked up the outside kitchen door (to allow more cupboard space - I have french doors to the garden in dining room). The first concern is he has not keyed in the new bricks in the doorway to the surrounding brickwork outside but has pinned it because he says the existing mortar is very strong/brittle and would make a mess of brickwork to remove/cut out half bricks (he found this with his house). He also has not laid inner cavity brickwork inside the doorway (house has cavity brick walls) but instead has laid plasterboard straight onto a timber framework around the doorway inside with an air/cavity gap (dry lined so the plasterboard is the inner cavity wall). I am spending a lot of money on kitchen installations and ceramic wall tiles and I am worried that having normal plasterboard directly over the cavity may allow damp and rot in. He has also put no cavity wall insulation in because he says there will be cupboards and tiles over it anyway. Am I right to be worried? Is it also OK to put kitchen tiles over normal plasterboard inside the kitchen or will I again get damp and rot from spillages/steam etc. I am aware of glasslined and moisture resistant plasterboard for wet/damp areas but it is expensive stuff - should these be used for the doorway or under the kitchen tiles instead? I dont want to go OTT here on expense but I do not want to ruin an expensive kitchen for the sake of a few quid saved on better plasterboard or better cavity insulation. Any help would be greatly appreciated either to put my mind at ease or how to put the wrongs right if necessary - this chap seems to know his stuff but I have little building knowledge myself. Thanks

[thedoctor]

Using frame crapms or ties to bond brickwork is acceptable its just not very pretty to have a straight joint. Toothing out is the best job but not necessarily any stronger. The easiest way to tooth out in hard mortar is shown in our removing a damaged brick project and involves drilling lots of holes to get the joint out. The plasterboard over the opening should really have some insulation between the back of it and the cavity. There should not be a damp problem but the cold air in the cavity can cause a cold surface on the plasterboard which could well be prone to condensation, especially in a kitchen, even with tiles on.
Tiling over plasterboard is perfectly OK. When the tiles are laid properly, and the grouting done well they are completely watertight and should give you no problems. The only thing we would say was not really up to scratch is the insulation on the back of the board which should not take long to rectify.

[Yorkshireshrek]

Thanks for your advice. I found some foil backed insulation sheeting from Wickes for about £13 which you just attach to the timber framework behind the plasterboard. It claims to offer thermal insulation and prevents condensation and damp ingress. Was dead easy to put on behind fresh plasterboard. I will probably end up rendering the outside wall or have climbing plants to mask the brickwork.