How to fit an internal door frame

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The door frame, or door lining , will hold the door in place. It's important to ensure the frame is assembled correctly and is installed straight, level, and plumb. The door can then be installed easily and will work correctly. 

  Door frames can be replaced if they wear down or get damaged  

Doors and frames can wear over time, or get damaged, and need replacing. New frames are often sold separately from the door slab, and come as a frame kit, with jambs, head, and stops, to be assembled on site. 


For more information on measuring for a door frame see: How to measure for a new doorset


Not all doors are the same, and you'll find there are different types of frame, so check the specific instructions with the frame you choose. Here is a basic guide to assembling and fitting a standard internal door frame without a sill, usually made from some kind of timber. Frames made from other materials may have different instructions about how they should be fixed together. The frame might need to be trimmed to fit correctly, so make sure you use an appropriate saw or a similar cutting tool.


Door frame kits 

  Frame heads can usually accommodate two sizes of door width  

An internal door frame kit  will usually consist of a head, two jambs, and separate stop pieces. The head piece can often accommodate two different sizes of door. The jambs fit into recessed parts in the head. These recesses are usually cut into the head at different distances on each side, so first you should determine which recesses you'll need to use by checking the door's width. 


Step 1 - Fix jambs to head

  Fit the jambs into the head of the frame  

Lay the frame on a clean, dry floor or appropriate workbench, where there is enough space to assemble it. Fit both jambs into the correct recesses in the head. You might need to use a hammer to tap them firmly in. You can then secure each jamb in place with a long screw. You now have the main parts of the basic frame assembled. 

      Buy internal doors with top quality finishes or primed and ready to paint  

Step 2 - Trim head

The head piece will usually be wider than you need it to be. You should trim either side of the head so it's just less than the width of the opening. Ideally, you should have just enough room around the frame to enable you to make slight adjustments when it's in the opening.


Step 3 - Brace frame

  Check all the sides of the door frame are level  

The frame needs to be level, straight, and plumb, and it should be as accurate as possible when you're installing it. Use pieces of scrap timber to build braces which will hold the frame in the correct shape while it's fitted. These should be nailed on with thin nails so they can be easily pulled off later. 


First brace the bottom of the frame. Measure the width between the jambs at the head of the door and fix the timber to the jambs at the bottom of the frame so they are the same distance apart all the way down. Then use a level and a set square to check the top corner on the jamb which will hold the hinges. This corner needs to be level and square. Use another piece of timber to fix this corner in a square position. You can do the same on the other top corner if you wish.


You can check how square the whole frame is by measuring corner to corner on the diagonal. These two measurements should be the same as each other. If there is a significant difference between measurements, more than 5mm, you should check and reposition the braces. 


Step 4 - Insert frame into opening

If the measurements are correct and the frame has been put together so it's completely level all around, you should be able to carefully push it into the rough opening. There should be enough space between the frame and the wall for you to make slight adjustments if you need to.


Step 5 - Pack and level frame

Use a spirit level to check the frame is still level and plumb. Use wedge shaped door packers or shims, thin pieces of material which will go between the frame and the wall, to align the frame correctly. These can be used to compensate for any places where the walls are not even. Ideally, your door frame will sit flush with the wall or protrude by about 1mm, especially if you are fitting architrave or trim.


You can put more than one shim or packer in where they're needed, so it's best to use particularly thin pieces you can build up if you need to. Long shims or packers are recommended as these are easier to adjust. The shims or packers should be placed roughly where you intend to insert your fixings to hold the frame in place, so they will go through them and into the wall. They should also be placed where the hinges will be. You can use a hammer if you need to knock them deeper into the gap.


Step 6 - Fix frame

The positioning of the fixings, usually nails or screws, depends on the type of wall they will go into - stud or brick. Get the head level first, and fix in place, then you should plumb and fix the jamb which will hold the hinges, securing the other jamb last. Use fixings which are at least 80mm (3⅛") long and appropriate for the wall material. Mark where the fixings will go first. If there is a sill, the instructions should explain when this should be installed.

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  Mark where you'll put the fixings when you attach the door frame to the wall  

Stud walls

You attach the fixings in pairs up the length of the jambs. Begin about 100mm (4") from the floor and then space them at around 450mm (17¾") intervals. They should be placed about 30-35mm (about 1¾") from the edge of either side of the jamb.

  Mark where you'll put the fixings when you attach the door frame to the brick or block wall  

Brick or block walls

To prevent bricks or blocks splitting, the fastenings must be staggered. They should each be fitted about a third of the way in from the edge of the jamb. The instructions should direct you with the correct spacing for your frame. 


Step 7 - Finish

Double check the frame is still straight, level, and plumb within the opening with a spirit level. To increase the accuracy of a shorter level over a longer length, you can fix it to a longer straight tool, like a rule or straightedge, or a long piece of straight timber. Once the frame is fixed in place the shims can be trimmed or scored with a knife and then hit with a hammer so they break off flush with the jambs.

  Frame for an internal door  

The frame is either finished with an appropriate filler or plaster, where it joins the wall, or where there are any recessed fixings. A trim, like architrave, to hide where the frame meets the wall is usually installed on internal door frames. There is a selection of stylish oak architraves and matching skirting boards  available that will compliment your door and provide a smart finish.


For information see: How to fit door architrave

      Wonkee Donkee says "If the door you're installing is a fire door it must be installed into an appropriate frame, with all relevant seals, to maintain its full  fire resisting value."  

How to fit a door stop to an internal door frame 


If the frame has separate stop pieces, which most internal door frames do, you'll need to mark where they go and attach them, usually with nails. The stops are what the door will sit against when it is closed. There are usually three stop pieces, for the top and both sides of the top quality internal door frames from xl joinery


Step 1 - Measure the thickness of the door

To position the stops correctly, you need to know how thick the door is so you can work out where it will sit when it's closed. It's best to measure in a few places along the edge of the door in case it is not a uniform thickness all along the edge. Use the largest of the measurements as your guide. 


Step 2 - Mark where the stops will go on the frame

Measure from the edge of the frame that the door will sit flush against when it is closed. Mark for the thickness of the door, on the jamb where the door handle will meet and also on the head piece. Mark a few places along the frame pieces. Use a set square if you can so you know the marks are all the same. 


Add about 1.5mm to the measurement when you mark it on the hinge jamb. This makes allowance for the corner of the door, on the hinged side, clearing the stop when it's opened and closed, ensuring it won't bind. These marks will guide where the stops need to be positioned.


Step 3 - Trim stops to size

  Cut the pieces of the door frame to the correct size for fitting  

Measure the inside of the frame head for the length of the top stop piece. Then measure the height of the inside frame and take off the thickness of the stop pieces, and allow for any flooring. Trim the pieces to size if necessary. 


Step 4 - Fix stops in place

Place the top stop pieces against the guidelines and fix into place. You can use wood glue as well as nails if you prefer. Make sure the pieces are straight and level; use a spirit level to check. Once the door is hung it should close perfectly against the stops.

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