Plastering and tiling a window sill

[Ian Clowes]

Hi all

I'm tiling the kitchen, and am pondering how to best prep the window sill.

After removing the current window board I'l looking at the top of the inner leaf of bricks, and the plastic cavity filler. I'm wondering about the best way to level this, make it a sturdy suface for tiling onto, and possibly including some insulation to prevent an overly cold feel or a cause of constant condensation.

Current ideas are:

1) Trim window board to match rising wall, and secure with screws and Gripfix. Board has sound gloss paint, which I'd hope would offer some moisture penetration protection, and hold the tiles if I give it a rough up with medium glass paper. Hoping wood will offer some insulation.

2) Add sandwich of plasterboard, polystyrene sheet and plasterboard. Each layer would be around 12mm thick. Combinations of PVA and Gripfix to keep it all in place.

3) Same as 2, but with a base layer of plaster into cleaned out and PVAed frogs on brickwork.

4) Plaster with polystyrene beads in it (50/50 mix by volume?) to build up an all-in-1 semi-insulated surface.

5) Just plaster. Its warm enough for walls, so why not window sills?

Any thoughts or stories from the trenches would be appreciated.

One final question: How long would 3/4" or so bed of plaster need to be left for before tiling onto?

IanC

[Andrew Gabriel]

I put a sand and cement bed on the top of the bricks, leveled and smoothed off. Later (about 3 years later in my case), I got round to tiling it. You can actually lay the tiles directly in the sand and cement, although they bond better if you do it separately afterwards with tile adhesive and it's easier to get a good level finish if you're not familiar with using mortar and laying bricks level.

[Ian Clowes]

Thanks Andrew

So you reckon not to worry about the condensation aspect?

And was that astandard bricklaying mortar mix (although for this small amount I'd probably just get a bag of ready mix repair stuff and go with whatever is in it)?

IanC

[seantovey]

In a similar situation I would either (as you suggested) fix the old adjusted board with screws or use plasterboard

[Housemartin]

Cement is a good idea, however if it is a reasonably large area say over 6" wide you can have problems with adhering the tiles if you don't let the cement dry for at least a couple of weeks before tiling (due to cement shrinkage).An alternative I use somtimes,is to use diy type filler eg Tetrion which only takes the night to dry. Regarding tiling on the window board you could screw some 12mm wpb ply to it then tile on top. This will lessen the chance of the board going rotten over time.