How big is market for replacement doors

[Fitter Steve]

Ive done a couple myself but never pushed it . I think there is a market for it though.

As for buying a franchise. Why not find a few good door suppliers and spend the money it would cost to buy a franchise on advertising and reap all the rewards yourself. That way you will be able to supply any make of door. You will also need to be able to supply the odd new unit, panels cornice etc and wirework. Thinking bout it you will need to be able to supply the whole lot that will be the easy part of setting the business up