constructing a door jam

I'm no expert, but I've done it a few times..

Firstly, your rough opening.. if you're putting in a 770, your rough opening should be at least 770 + 20 (gap) + 18*2 (jamb width) + at least 20mm for fudging the jamb = 846mm.

You should try to get the sides & top fairly square, but it's not critical at this point. It's more critical to get it plumb. I then cut the jamb to the correct width & height for the door (don't forget the 15-20mm gap) and assemble it on the ground. Then you can stand it up and walk it over the the opening and get the fairly close to plumb & level and put a single framing nail into one side, in the centre (where it will be covered by the stop).

Once you have one side done, get the other side looking pretty good and put another nail through the centre. At this point, you can get a chisel and tweak the frame around a bit to square it up if required.

At this point, I put in another nail near the top of the frame on the hinge side and hang the door. I then get all the gaps set correctly to the door and make sure everything opens & closes ok. Other people I know simply get the dimensions right and make sure it's perfectly square & plumb, but I prefer to get the door in as soon as I can as it's easy to get a nice wave in your door frame and miss it if your level isn't long enough.

Once you've got it all looking good, put a few more nails in, but this time nail through some packing material - this will depend on the gap between the frame and the rough opening, but use whatever timber or wall packers you have handy.

Then nail on the arcs which will lock everything into place permanently..

You should then put the handle/lock mechanism into the door and cut the corresponding rebate into the door frame for the latch. Then cut the stop and cover most of the framing nail holes you have left down the centre of the frame. Use a bit of paper folded over a few times for a gap between the door & the stop, otherwise your door may not close once you have painted everything.

Once you've done one it gets easier. Just go slow and use a good long level..

Originally Posted by cflake

I'm no expert, but I've done it a few times..

Firstly, your rough opening.. if you're putting in a 770, your rough opening should be at least 770 + 20 (gap) + 18*2 (jamb width) + at least 20mm for fudging the jamb = 846mm.

You should try to get the sides & top fairly square, but it's not critical at this point. It's more critical to get it plumb. I then cut the jamb to the correct width & height for the door (don't forget the 15-20mm gap) and assemble it on the ground. Then you can stand it up and walk it over the the opening and get the fairly close to plumb & level and put a single framing nail into one side, in the centre (where it will be covered by the stop).

Once you have one side done, get the other side looking pretty good and put another nail through the centre. At this point, you can get a chisel and tweak the frame around a bit to square it up if required.

At this point, I put in another nail near the top of the frame on the hinge side and hang the door. I then get all the gaps set correctly to the door and make sure everything opens & closes ok. Other people I know simply get the dimensions right and make sure it's perfectly square & plumb, but I prefer to get the door in as soon as I can as it's easy to get a nice wave in your door frame and miss it if your level isn't long enough.

Once you've got it all looking good, put a few more nails in, but this time nail through some packing material - this will depend on the gap between the frame and the rough opening, but use whatever timber or wall packers you have handy.

Then nail on the arcs which will lock everything into place permanently..

You should then put the handle/lock mechanism into the door and cut the corresponding rebate into the door frame for the latch. Then cut the stop and cover most of the framing nail holes you have left down the centre of the frame. Use a bit of paper folded over a few times for a gap between the door & the stop, otherwise your door may not close once you have painted everything.

Once you've done one it gets easier. Just go slow and use a good long level..

Thanks mate,

I appreciate all that detailed info.

Unfortunately I did the job today before I read it. It's worked out ok, so far. Architraves on tomorrow.

I know what you mean about the wave in the jam. I hope I avoided it. I just used a spare bit of timber as a straight edge.

A couple of things that you might find handy, in the future, if you don't know already -

- for packing small gaps I use malthoid. It's about 1 mm thick bitumenous sheet

- yesterday,a builder friend of mine cut in a rebate in the top of the jam for each side piece - it made the whole job so much easier

Thanks again

Cheers

Mark