How to hang a door, and why it takes longer than you think

Hanging a door is one of the jobs Homesmith gets asked about most, usually by somebody who has already had a go at it themselves.

It starts well. The door goes up, it swings, it closes. Then it catches on the top corner of the frame, or it drifts open every time you leave it half shut, or the latch only holds if you lift the handle on the way past. Everything about it is nearly right.

That is the shape of this job. Getting a door into an opening is quick. Getting it to sit correctly in that opening is what takes the time.

What to consider before anything gets cut

Decide which way it swings first. Look at what sits behind the door once it is open, whether it clashes with another door in a hallway, and whether a light switch ends up hidden behind it. Changing your mind after the mortices are cut means filling the jamb.

Work out what is going on the floor. If new flooring, carpet or tiles are coming, the door gets cut to the finished floor height. Doors hung before the floor goes down get cut twice.

Choose solid or hollow core. A hollow core door is light and cheap and takes two hinges, but it only has solid timber in certain places inside it, so the handle and the hinges have to land where there is something to fix to. A solid core door hangs better and sounds better, and it needs three hinges and heavier hardware.

Pick the hardware for where the house is. Anywhere from Byron Bay through to Ballina the air carries salt a long way back from the beach, and standard zinc plated hinges and strike plates go off within a few years. They stain the paint around them first and seize later. Solid brass or stainless costs more at the counter and it is what stops you doing the same door twice.

Check whether it has to match the rest of the house. One new door in a hallway of six existing ones reads as new unless the style and the hardware line up. That is often the reason a door gets repaired instead of replaced.

Bathroom and laundry doors are their own thing. They need more clearance at the bottom for airflow, and they take more moisture than any other door in the house.

What size door do you need

Australian internal doors come in a short list of standard sizes, so most of the question is which one is closest and how much has to come off it. Put the opening measurements in below.

What is actually involved

The order matters more than any single step, because each step is measured off the one before it.

Measure the opening in more than one spot. Width at the top, middle and bottom, and height down both sides. Those numbers will not all match, and the smallest one is the one that counts.

Check the frame for twist. Sight from one jamb across to the other and see whether the two sit in the same plane. A frame in wind holds the door off the stop at one corner no matter how well the rest of it is fitted, and no gap adjustment will fix it.

Cut the door to the opening. Standard internal doors here are 2040 x 820 or 2040 x 720, so in a house built after about 1980 there is usually very little to come off. Anything built before the mid 1970s is imperial, and those openings run around 2 foot 6 or 2 foot 8 wide and 6 foot 6 high, so a modern door has to be cut down to fit. Take more than about 20mm off a hollow core door and you run out of the solid rail at the edge, so there is nothing left to fix a hinge into. In an older cottage the answer is often a solid door made to size, or keeping the original door and repairing it.

Cut the hinge mortices. Two hinges on a hollow core door, three on solid core or anything carrying weight. Standard is a 100 x 75mm butt hinge set 150 to 175mm down from the top and up from the bottom.

Hang it and check the swing before going anywhere near the latch.

Then the latch and the strike plate, marked off the door sitting in its closed position rather than measured off the jamb.

Nothing about the opening is square

This is the part that catches people out, and it has nothing to do with skill.

A door is a rectangle. An opening in a house that has been standing for thirty years is not. Timber shrinks, the floor drops a few millimetres at one end of the hallway and the frame goes with it. A lot of the housing between Bangalow and Alstonville is timber framed and up on stumps, and stumps in this soil move with the wet, so the openings move a little every year. The frames that come out worst are in houses that have been raised, restumped or repaired after flooding, where the floor now sits at a different level to the one the frames were built to.

So the opening is a very slight parallelogram, and the door has to be cut to match it. A door cut perfectly square into an opening that is 4mm out will have a gap tapering from 2mm at the top to 6mm at the bottom. The eye picks that up immediately, even though nobody could tell you the measurement.

The answer is to scribe the door to the opening instead of cutting it to a number. You mark the real line of the jamb onto the door and cut to that line. It is slower, and it is the difference between a gap that is even and a gap that looks even.

The gaps are the whole job

Everything visible about a hung door comes down to four gaps.

Down each side and across the top, 2 to 3mm. Consistent matters more than the number itself. A 3mm gap that stays at 3mm the whole way looks correct. A gap that runs from 2mm to 4mm looks wrong even when the door never catches on anything.

At the bottom, roughly 10 to 20mm over carpet and 5 to 10mm over tile or timber, with the bigger end of that in bathrooms and laundries.

The gap you will actually notice is the one down the lock side, because that is the one sitting at eye height while you are standing at the handle.

Hinges are where most of it goes wrong

A hinge mortice has to be exactly the thickness of the hinge leaf.

Cut it a millimetre too deep and the door binds against the jamb on the hinge side, so it either will not close or it springs back off the latch. Cut it a millimetre too shallow and the leaf sits proud. That holds the door off the frame, opens the gap on the hinge side and tightens it on the lock side.

Small error at the hinge, large error at the latch. The hinge is the pivot and the door is 820mm wide, so a millimetre out at the hinge is three or four millimetres out by the time it reaches the other edge. Most doors that will not latch are being caused by a hinge.

The fine tuning is a piece of card behind the hinge leaf. Packers behind one or both hinges shift the door across in fractions of a millimetre, and that is what most adjustment actually is.

One more thing happens at this stage. A door cut dead square on the lock edge catches on the jamb as it swings, because the trailing corner of that edge travels through a wider arc than the face of the door does. Take about 3 degrees off the lock edge, leaning away from the direction it closes, and it clears. On a 35mm door that is under 2mm of taper. You cannot see it when the door is shut and it is why the door closes without rubbing.

Hanging a door in an existing frame

Most of the doors we hang go into a frame that is already there, and the frame sets the terms.

The first thing to establish is whether the existing hinge positions can be reused. If they can, the new door gets its mortices marked straight off the old door and the frame is never touched. That is the quick version of this job and it is worth spending time to find out whether it is available to you.

If the frame has moved far enough that the old positions no longer work, you are either filling and recutting the jamb mortices or shifting the hinges up or down on both the door and the frame. Filling a mortice in a painted jamb is straightforward. Filling one in a stained hardwood jamb is a different job, and that is the point where hanging a door becomes a repair.

Two things worth checking before any of that. Whether the jamb has solid timber left in it, because opening one up around here turns up termite damage often enough to expect it, and a hinge screw needs something to bite into. And when the door was last touched. A lot of doors in the district were rehung in a hurry while the house was still damp. A door scribed to a swollen frame is loose once everything dries out, and a door that was itself swollen when it was fitted binds from then on. If a door has never sat right since it was replaced, that is usually why, and it needs recutting rather than adjusting.

Seal all six edges

A door has six surfaces. Two faces, two long edges, the top and the bottom. On most jobs four of them get painted and the top and bottom get left, because nobody is ever going to see them.

That is exactly where the water goes in. Timber takes moisture up through its end grain, and our summers sit at high humidity for months at a time. The door swells, then bows, then starts catching on the jamb in February and clearing again in July. People put that down to the house moving. Usually it is the door.

If a door has been cut down, the fresh edge is raw timber or exposed core, and it has to be sealed before the door goes back up.

What a good one looks like when it is finished

There is a simple test. Open the door to halfway and let go. It should stay exactly where you left it. A door that swings shut on its own is leaning back into the frame and one that swings open is leaning out. Either way the hinge line is out of plumb, and it gets worse over the years as the screws work loose.

After that, four things. The latch holds with the door pushed, without lifting the handle or pulling it towards you. The gap follows the jamb the whole way down, including the places where the jamb is not straight. The hinge leaves sit flush enough that you can run a finger over the join without feeling a step. And every cut edge is sanded and sealed, the top and bottom included.

What you can do yourself

Plenty of it. Swapping a like for like door into a frame where the old hinges line up and nothing needs trimming is a real DIY job, and we will tell you that if you ask.

The ones worth handing over are doors that need cutting to a frame that has moved, and anything where the jamb or the architrave is stained timber rather than painted, because a filled mortice in a stained finish has to be colour matched and cannot be sanded back and tried again.

Fire rated doors in units and common areas are separate again. They are tagged, the gaps are specified and the installation has to be certified, so they are not a handyman job for anyone.

The practical one is weight. A 2040 x 820 solid core door is around 35kg and it has to be held at the right height and plumb while the first screw goes in. Wedges under the bottom edge do a lot of that work. It is still a two person job.

What it costs

Homesmith prices doors as part of a day rather than per door. Pricing is $420 + GST for a half day or $760 + GST for a full day, for one smith.

A day is not one door taking eight hours. It is the door, the frame it has to fit, the hardware, the adjustment once it is hanging and the touch up on the cut edges, and then whatever else is on your list while we are in the house. Several straight swaps into frames that have not moved go in the same day, alongside the rest of the list. One door into a frame that has moved, with the mortices recut and the architraves scribed back, takes a good part of a day on its own. Finishing and repair work on stained or specialty timber is quoted above the day rate.

Send the list and a photo of the door and the frame and a fixed price comes back, usually within the hour.

Questions