Alex,Besides slightly sloping the outside capping to allow water runoff. I would also do the following move the window out much closer to the exterior surface. This does 2 things it avoids possible moisture problems in an area that is difficult to inspect and it also improves the insulation value of the structure. There is less external surface working as a heat sink. This is a general rule for any type of building structure. The less the external exterior surface area for a given volume the more thermically efficient it will be. Another effect is that it lessens the effect of cold bridges which are always a potential problem around wall openings. Another effect which can be of some importance is that by reducing the external surface area maintenance is also reduced. There is less external surface area to deal with which requires the most maintenance.
The above again should also be considered in some balance because when pushed to an extreme moving the window flush to the outside surface or even projecting it out is not a good idea either. A window frame is quite a complicated (expensive) structure and also deserves some protection so it is a good idea to keep it back somewhat form the outside surface. In your case where you have big overhangs this is not such a necessity and you only need a small setback maybe about 100mm.
At 07:36 AM 2/1/04, you wrote:
What I'm wondering is does anyone have any advice for capping the top of the wall ? Can I just use lime or would I be better with some other form of capping ? The plan is for the structure to look clean and smooth so I would like to avoid a heavy visible capping if at all possible. The window will be about 1m in depth. and the overhang about 2m.
Rene Dalmeijer