how can i trim my door?

There are two tools available which will trim a door whilst hanging. the better of the two is called a plunge saw which is a variation of a circular saw the other is a multifunction tool called a sonicrafter/multimaster. these are made by bosch, worx and fein but unless you can borrow/hire one of these i would say take the door off and get the saw out.

Yorkshire chippie
October 2009