Installing an internal door might seem like a daunting task, especially if it’s new territory for you and you’ve never done it before. Whether you’re a seasoned construction worker or you’re taking on a home renovation project, with the right guidance, fitting an internal door can be a fairly straightforward task.
In this step-by-step guide, we’ll talk through how to fit an internal door frame and an internal door to not only ensure a successful installation, but also a smooth professional finish.
Tools you’ll need to hang your internal door and frame
Before you begin installing an internal door, you need to ensure you have the right tools at your disposal first. Some essential tools include:
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Oak or timber board
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Your chosen door
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Hinges
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Tapered and flat wood shims
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Saw
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Electric drill
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Nails and screws
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Spirit level (long and short)
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Measuring tape
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Safety goggles
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Hammer
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Sand paper
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Chisel and plane
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Screwdriver
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Pencil
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Concrete cement (optional)
How to fit an internal door frame
Before you hang an internal door, you need a frame that’s properly aligned. The first part of this guide will walk you through the key steps so everything is ready for when you install the door.
Step 1: Mark out your measurements
Before you assemble the frame, you need to measure the opening. Use a measuring tape, measure the inside width of the doorway in three places (the top, middle, and bottom), and take the largest measurement.
Then, measure the inside height from the floor to the head in three places (left, centre, and right), and again, use the largest measurement. If your floor is unfinished, make sure you leave a gap at the bottom as you will need to account for the type of floor that will be fitted.
Finally, measure the thickness of the wall. Once you have all three of these measurements, you can select a timber that matches, or is slightly larger than your opening.
Step 2: Cut out your frame
Now you have your measurements, you can cut your frame. This will be made up of two door jambs (the side pieces) and a head (the head of the frame). You’ll need to cut all three to size properly.
To do this, get the timber you have selected and use a pencil to mark where it needs to be trimmed based on your measurements. Once all your measurements have been marked out, chop the wood and use sandpaper to smooth out edges.
Step 3: Assemble and fit the frame
Now you have your jambs and head cut to size, it’s time to assemble your internal door frame. First, mark where you’re going to drill two clearance holes through the top of each of the jambs – this will be where they’re going to connect to the head.
Laying all your pieces on a flat surface, drill the holes and place the jambs together against the head. Then, use wood screws to secure the jamb to the head on both sides – you can use wood glue to help hold the frame in place before putting the screws in if you wish to. When assembling your internal door frame, take care to make sure everything is flush.
Before fitting the frame, place temporary wooden braces to help stop it from shifting during installation. Add one at the bottom of the frame – to help support the bottom of the jambs – and one across a corner to help keep the angle correct when you’re fitting it – you can also use a utility square to make sure the angles of the frame are correct. When you’re happy that the frame is being held in the correct position, lift the frame and fit into the opening.
Top tip: Never fit a door frame onto an unfinished floor. Instead, use inch blocks under the bottom of the frame if you’re planning to fit a carpet – or something smaller for hard floor types.
Step 4: Plumb the frame with shims
Once your internal door frame is in place, you’ll want to fill any gaps around the edges with shims to ensure it’s plumb. Begin inserting them into the largest gaps on all sides. For smaller gaps, gently tap the shims with a hammer to push them further in.
Keep adjusting the shims until the frame has an even reveal around it by using a spirit level. If there are any areas that aren’t level, you add more shims and fill the gaps with concrete cement.
Step 5: Mount the door frame
Once your internal door frame is plumb, it’s ready to secure into the wall. First, mark where you’re going to place your screws. This may vary based on what you’re fixing onto. For example, you may need to space differently and use wall plugs if you’re drilling into brick.
Mark out the first pair of fixing points 100mm up from the bottom of the jamb. Then, space them 450mm apart all the way up in pairs. Once they’re all marked up, secure the frame to those points. You’ll want to use longer screws near the hinge point to add extra support.
Finally, remove the wooden braces you put in to support the frame and you’re ready to hang your internal door.
How to fit an internal door
Now you have your internal door frame ready, it’s time to fit the door. Hanging an internal door is a fairly straightforward process with the right basics. Here’s our step-by-step guide to get a clean, reliable fit.
Step 1: Mark out any trimming and reduce the size of your door if needed
The first step is to make sure your door is going to fit your frame perfectly, and this may mean having to trim the door. If this is the case, you’ll want to measure out where you need to cut. If it’s only a few millimetres, you can take it off from the bottom. If there’s quite a lot to trim, you’ll need to take it evenly from the top and bottom.
Step 2: Mark the position of your hinges
Once you’ve trimmed your door, next you’ll need to mark the position of the hinges. You want them to be flush so that the door will open smoothly. To do this, outline the top hinge around 6 inches down from the top of the door, and then the bottom hinge 10 inches up from the bottom. The middle hinge should be centred between the top and bottom.
Mark them out one at a time with a pencil. You can also use a utility knife to create a groove around the hinge to make the next step a little easier if you wish.
Step 3: Cut your hinge plates
Using a sharp chisel, remove the wood inside the outline you just marked for the hinges. Test the fit of the hinge as you go as you’ll want it to sit perfectly flat.
Then, lift your door against the frame (without the hinges attached) and place two flat shims along the top of the door. Place a door stop under the bottom of the door so it’s sat in the right position, flush against the shims at the top. This will help keep a gap between the top of your door and the frame. Mark on the jambs where the hinge plates will sit and remove the door again.
Then, just like you did on the door, remove the wood inside the marking on the door frame for the hinge plates.
Step 4: Fix your door hinges
To fix your door hinges, start by attaching them to the door by marking the screw holes with a pencil or awl. Then, remove the hinge and pre-drill a small hole to help the screw fit in straight, or simply screw straight in.
Once all three hinges are attached, hold the door up to the frame and line up the hinge with the hinge plate on the frame jamb. Then, attach the hinge onto the frame.
Step 5: Install the latch and lock
Next, attach the lock and latch to your door’s edge. Most kits will come with instructions to show the correct place they need to be installed on the doors edge, so ensure you follow these guides.
Step 6: Seal the door
To protect your internal door against indoor moisture and humidity, we recommend sealing it. Doing this will not only keep your door looking clean and fresh for longer, but also prevent it from swelling or warping too.
Get a quote from us today
At JTD Building Supplies, we can provide you with all the materials you need to build and install an internal door and frame. We stock a wide range of timber, doors, mouldings, and tools to get you started with your internal door project.
If you’d like further expert advice on how to fit an internal door and frame, or to learn more about our products, don’t hesitate to get in touch with us today. We can provide you with a competitive quote for our products and provide you with expert advice on the best materials for your project.
Fitting an internal door FAQs
Can I fit a new door into an existing frame?
Yes, if the existing frame is in good condition and square. However, if the frame is warped, damaged, or not the right size for the new door, it’s best to install a new frame to ensure a proper fit and smooth closing.
What size gap should I leave around an internal door?
You should allow a 2-3 mm gap on each side and at the top to let the door close freely, and around 10mm at the bottom for ventilation and floor clearance, especially if you’re fitting over carpet or tiles.
Should I use screws or nails for fixing the door frame?
Screws are generally recommended for fixing frames, as they allow you to adjust the frame easily and create a stronger hold. Use long screws (around 100mm) and ensure they’re fixed into the surrounding masonry or studwork.
Can I use expanding foam around the door frame?
Expanding foam can be used to fill gaps between the frame and wall, but apply sparingly. Once cured, trim the excess and cover with architrave for a neat finish. Always ensure the frame remains square while the foam sets.
