aluminium sills
Over sills
One of the most common question asked is how do you deal with the sill when the existing sill is too short to extend out over an insulated system? This is an understandable question because your window sills have to protrude out from the wall to enable the water to run off properly when it rains. Without a window sill, the rainwater can pool and cause damp problems with resulting damp problems and/or wall staining. The ideal solution is to use an aluminium over sill. These can be used on top of a PVC, tiled or stone sill. When finished these sills can look like part of the window.
They are supplied with welded end caps normally with a fixing lug so therefore they can be used in exposed locations.
In order to look part of the window the aluminium sill can be powder coated to a similar colour to the window. Unfortunately they can not be made to look like wood-grain.
When installing these aluminium over sills it is important that any weep holes in the window are not blocked.
We are trying to design over sills now to be fully watertight without the need for silicone sealants.
On high risers we try to design the sill with a 45 deg slope so that it prevents pigeons from nesting. Unfortunately, the existing PVC sills are not designed with this in mind.
Over sills were used in this case to not only project past the steel reinforcing but also it had to cover the insulated system placed on top. These sills were provided with structural calculations to give the reassurance that they would stay on the building.
