Repairs: joinery, doors and kitchens

The mitres around any bay windows are notorious sites for moisture ingress. The mitres shrink back, then water enters the open joint and causes decay at the end grain.

Solution 1

If you encounter the problem before significant decay has taken hold, a 2-pack resin may be the answer.

Solution 2

If decay is significant, you may need to carefully split off any defective cills before installing new.

Traditionally this was achieved by fixing screws into the sound timber once the cill had split off, and drilling holes corresponding with the screw heads, in the new cill section. This was then set over the screw heads and hammered sideways so that the screws bit into the timber. However, this method does not guarantee a good joint/union between the new cill and the old timber, and water could soon enter the gap, causing further decay at great depth back into the cill or window frame section.

Use of 2-pack resin buttered and pasted along the old timber frame to provide a good seal is probably a more efficient and effective solution.

The mitres will always present a problem, however, and it may be best to cut back the mitre slightly and provide a substantial filling of resin rather than try to paint-fill a hairline crack, which will inevitably open up and allow water penetration sooner or later.