To fit architrave around a door you will have to cut four mitres, two in the head (top) piece and one in each of the two side pieces. Architrave is normally set back around 1/4″ (5mm) from the edge of the door casing, (see fig 1). We do this so the architrave doesn’t impede the fitting of the door hinges (see – how to hang an internal door).
Mark the 1/4″ (5mm) line around the edge of the door casing first, now cut the head piece with two mitres to length allowing for the additional 1/4″ (5mm) each end, (see fig 2).
To cut the mitres you can use either a mitre box and wood saw or a power mitre saw (see the end of the post for a full list of the tools required for the job).
When you’ve made the cuts, lightly sand the cut ends smooth if required.
Fix this piece in position using three or four 2″ (50mm) lost head, round or oval nails. Hammer them in about halfway to start with.
Saw each floor end of the two side pieces of architrave square and place each one in turn against the door casing in line with your 1/4″ (5mm) guide line.
Mark where the mitre needs to be cut using the bottom edge of the head piece mitre as a guide, (see fig 3) and make the cut(s).
Again, fix the two pieces in position using seven or eight 2″ (50mm) lost head, round or oval nails only hammering them in about halfway.
When you are satisfied with the finished appearance of the architrave and the mitres, hammer the nails in flush with the surface of the architrave and then sink them below it using a nail punch and hammer.
These holes can be filled and painted over.
Fill any small gaps in the mitres and around the outside edges of the architrave using decorators caulk to give a professional finish when painted.
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- Set square
- Tape measure
- Mitre box
- Oval nails
- Centre punch
- Wood glue or gripfill
- Tenon saw or jigsaw
- Safety goggles
Video: How to fit an architrave
Source: Tommy’s Trade Secrets