Where flat roofs bond to tile or slate roofs; tiles or slates should be removed and not fibre glassed over.

We always remove all boards, and not overboard over old and crumbling chipboards.

And always insulate the roof where necessary. Re-boarding only in sterling or ply boards.

Cracking and splitting bitumen felt,but ply boards underneath are still in a good condition. Sealant can be used on this roof to extend its life a few more years.

This is the same roof as the above photo with sealant, making sure that the whole roof is covered. This can only be done when the boards are still good and not collapsing. When using sealant make sure that it is applied to the correct surface and it must have some elasticity because of expansion.