Fitting Timber Door Frames & Hanging Doors

A good result starts with measuring. The width and height of the opening are measured in at least three places, and the wall thickness at the top and at the bottom. The finished floor height matters most, because the frame sits on the final floor covering, not on bare concrete. If the floor is not laid yet, you need to know exactly how thick it will be.

The fitting itself usually follows these stages:

• Checking the opening: remove dust, check that the edges are solid, the walls plumb and the floor level
• Assembling the frame: the frame is put together on a soft surface following the manufacturer's instructions, with square joints and no gaps
• Setting and levelling: the frame goes into the opening and is set plumb and level with wedges and a spirit level
• Spacers and foam: spacers go inside the frame so it cannot narrow, then the gap between frame and wall is filled with expanding foam
• Curing and finishing: once the foam has set, the wedges come out, excess foam is trimmed and the second lining or the architraves are fitted

Wedges belong mainly at the hinges and at the lock, because that is where the load is greatest. The foam is only there to hold and seal the frame, not to straighten it. That is why the position is fixed mechanically before any foam goes in.

Once the frame holds firm, the door leaf is hung. The hinges on most modern interior door sets adjust for height and sideways position, and some types also for depth. The leaf is adjusted gradually, in small steps, and the gap around the edge is checked after each change. According to most manufacturers this gap is usually roughly 2 to 4 mm, and it should be even all the way round.

After that, check:

• That the door opens and closes smoothly without rubbing
• That the latch drops neatly into the strike plate
• That the handle and fittings are firm
• That the leaf does not catch on the floor or the frame anywhere
• That the seal makes contact all the way round

Why does a door sometimes swing open on its own, or slowly close by itself? Almost always it means the frame is not quite plumb. The hinges can correct this a little, but only a properly aligned frame really fixes it.

The simplest case is a new build with straight walls, a finished floor and an opening that matches the frame size. Then fitting goes quickly and needs no extra work.

More time and effort is needed for:

• Removing an old steel frame and repairing damaged edges of the opening
• Uneven or crumbling masonry in older houses
• A wall whose thickness falls outside the range of the adjustable lining
• An uneven floor, or a floor that will only be replaced later
• A plasterboard stud wall without a reinforced opening
• A heavy door leaf, concealed hinges or non-standard sizes

If the opening has to be widened or newly cut in a load-bearing wall, this is no longer carpentry but a structural change. It needs a structural engineer's assessment, and you should check with your local building authority beforehand what approval or notice the change needs under local building regulations. In a block of flats, also talk to the building management or owners' association before any such work.

In practice, most problems with interior doors are not caused by the product but by the fitting. These are the typical ones:

• Inaccurate measuring: the opening is too wide or too narrow, the gap ends up filled with too much foam and the frame twists
• Forgetting the floor: the frame is set on concrete, and once tiles or a floating floor go down, the door drags
• Too much foam: as it expands, foam pushes on the frame and bows it inwards, which is why low-expansion foam and spacers are used
• Using the door too soon: the door is hung and used before the foam has fully cured
• Fitting in a damp building: timber and chipboard absorb moisture from fresh plaster and screed and later warp

Door frames do best when all wet trades are finished, the indoor temperature is stable and the relative humidity is roughly between 40 and 60 percent.

A handy homeowner can fit a wraparound frame alone if you have an accurate spirit level, a foam gun and some patience. A helper to hold the frame makes the job much easier. For removing old steel frames, or for any change to a load-bearing wall, it is better to leave the work to a professional.

1. Measure the opening in three places for width and height, and check the wall thickness.
2. Find out the finished floor height and use it to set the bottom of the frame.
3. Unpack the frame, check all parts and leave it in the room for a few days to acclimatise.
4. Assemble the frame on a blanket or cardboard exactly as the manufacturer describes.
5. Place the frame in the opening and secure it with wedges at the hinges, the lock and the corners.
6. Set both uprights plumb and the head level with a spirit level, and check the diagonals too.
7. Fit spacers inside the frame, ideally three along the height and one under the head.
8. Cover the frame surface with masking tape so foam cannot stain it.
9. Foam the gap in sections and sparingly, only to about a third of its depth.
10. Let the foam cure for the time the manufacturer states, and do not load the frame meanwhile.
11. Remove the spacers and wedges, then trim the excess foam.
12. Fit the second lining or the architraves.
13. Hang the door on its hinges and adjust the gaps around the edge step by step.
14. Test the lock, handle and swing of the door, and fine-tune the hinges if needed.

When the work is handed over, spend a few minutes checking while the carpenter is still there:

• Frame uprights are plumb and the head is level, checked with a spirit level
• The gap between leaf and frame is even all the way round
• The door stays put in any position and does not move on its own
• The leaf does not rub on the floor or the frame anywhere
• The latch engages the strike plate without pushing
• The seal makes contact all the way round
• Linings and architraves sit tight to the wall with no foam showing
• The frame surface, plaster and floor are undamaged