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 a

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