garage doors

[terence7556]

i have a qoutation for an pair of extensions on my home, one that includes a garage door.
one builder has excluded supplying and fitting the garage up and over door. why is this?, is it something to do with the warrenty on the door or the tensioning arrangement.
is the usual situation that the supplier of the door only guarantees it, if they fit it?

[Clanad]

That's usually the case, at least here in the U.S. While not terribly complicated, the installation of such a door and the balancing of the spring(s) can be tedious and in the case of the main spring downright dangerous if one doesn't know what they're doing.