shower tiling in roof

[jonnyp1]

am redoing my bathroom that is in the roof space so the walls are angled up to a point at the roof. i intend to tank (bal?) around shower and then tile. my question is as some of the tiles will be hung at 45 degrees or so what advice to get tiles on and keep them up. size, thickness tiles, ceramic? which adhesive? which grout?
cheers jon

 

[Richard C]

Assuming your fixing to plasterboard;
What thickness of plasterboard is it?
What spacing are the joists/battens it’s fixed to?
Has the PB been plaster skimmed or is it bare board?
What size/weight of tiles were you thinking of?

 

[jonnyp1]

richard
back wall is vertical brick on which i will build a partition (cant get depth of valve in wall on own) which will have 2 layers of 12mm plasterboard. the side walls which have the angle of the gable roof in are rafters with 300 mm between on which i will place 1 layer 12mm plasterboard, area 800mm width 800mm vertical, then the angle upto roof ridge of 1200mm .all unskimmed. i havent picked tiles but want largest that wont endanger through weight any suggestions?
cheers jon

 

[Richard C]

Pitch the virtical studs at maximum 400mm with at least 1 intermediate noggin & fully support that recessed shower valve; don’t skim before tiling. Correctly fixed unplastered Gypsum boards will support 32 kg/sq m, plastering reduces this to 20 kg/sq m, BAL WP1 is rated @ 32 kg/sq m. Fine so far but for the 45 degree ceiling, I would reduce that by around 50% (15 kg/sq m); you may be able to safely go to 20 kg/sq m but I'm guessing. Use a quality powder cement based flexible adhesive & grout which adds around 4 kg/sq m which will come of your maximum tile weight allowance.

Another option would be to use Aquapanel tile backer board rather than PB on the angled bit; this will accept weights up to 50 kg/sq m, so increasing the weight you can safely hang on the angled bit up to around 25 kg/sq m+.

Have you considered using Aquapanel over the entire shower area? This is always my preferred choice, especially where recessed shower valves are involved as these put a potential for water problems behind the boards; in this case an exterior tanking membrane won’t help at all as the PB will turn to mush from the inside! Aquapanel doesn’t require tanking so quicker & less work & it works out cheaper if you take into account the cost of the tanking kit.