Fitting architrave around a doorway properly is not the most difficult of DIY job, but it important to the finished look of any internal doorway. Architrave not only hides the joint between the door lining and the wall, but it also makes the doorway look complete.
Architrave is available in a wide variety of styles, but there are only two main types: Classical type, made up of square corner blocks joined by straight moulded or fluted sections. Or Standard type architrave, which consists of three straight sections of shaped wood, mitred at the corners.
Fitting Standard Architrave
Hold a short length of the architrave against the wall above the doorway, leaving a 6mm gap between the bottom edge of the architrave and the opening. Make sure the piece of architrave is level and then make a mark on the wall at the top and bottom edge. Using a straight edge and a spirit level, extend this mark to about 150mm beyond each side of the opening.
Measure from the floor to 50mm above the top line you just marked and then cut a section of architrave at this length. Hold this upright at the side of the opening, about 6mmm in from the edge, and mark its position, along the full length, on the wall. Where the upright meets the two lines you marked above the door, transfer the two marks onto the both edges of the architrave. Cutting diagonally from the top mark on the outer edge, to the bottom mark on the inner edge will give you the angle of the mitre, which you can then cut.
Repeat this process on the opposite side of the doorway and nail the two uprights in place with lost-head nails set at about 300mm intervals. Don’t hammer the nails completely home at this point, as you may need to make adjustments. Remember to double check the uprights with a spirit level before nailing them in place.
Cut a length of architrave slightly wider than the doorway (including the uprights) and then hold this upside down against the wall above the points of the two mitres of the uprights. Mark the position of the two points of these mitres on the piece of architrave. Flip the piece around so it is the right way up and hold it across the two uprights. Making sure the points of the two upright mitres are level with the top edge, and that the two marks you just made also line up with them, mark the bottom of the mitre. You can then cut the two mitres and slot the top member into place above the doorway.
Nail this in place along it’s length and then drive a nail from the top of the architrave diagonally through the two mitred corners. If everything is still level and looking good, you can drive home all the nails, using a nail punch to hide the heads below the surface of the wood. Fill the holes and joints with wood filler, before priming and painting the architrave.