Perhaps we should have written this article sooner, but seen as we haven’t it’s about time we did! When it comes to fitting door frames in a newly built property or when replacing existing frames, it’s crucial to install them perfectly level and square so that when it comes to hanging the interior doors and fitting interior door handles you end up with a faultless doorway. At the same time as ensuring that the door frame is fitted level and square it is also important to make sure that the left and right trims of the frame are running perfectly parallel with each other so that you don’t end up with doors that when closed the bottom reaches the frame before the top, or the other way round. Door latches and door locks that don’t locate the strike plate are another common issue caused with frames that are unsquared.

Assembling the Door Frame

If you haven’t purchased pre-assembled frames then you will need to assemble them before being able to fit them. Door frames that aren’t pre-assembled will come with the left and right trims, header and still. Some frames have headers that are the same thickness as the side trims and others have headers that are narrower. If the headers are the same thickness then this allows for you to assemble the frame whichever way around you choose, whereas in the case the header is of a different thickness you must assemble the trims the correct way, allowing for the doors width. Once you have determined the assembly plan, you can slot them together using amble wood glue and 3 wood screws on each joint.

Squaring the Door Frame

It makes for a much tidier and quicker install if the frame is perfectly square and parallel. You can check this by taking the measurements diagonally from the bottom right to the top left and the bottom left to the top right corners and if square you’ll find these measurements are identical. If there not, then loosen of the screws and adjust/realign and tighten the screws before checking again.

Bracing the Frame

If fitting a standard interior door, it will be easiest if you brace the side trims towards the bottom so that they are held apart at the exact same distance as that of the top of the frame. A diagonal brace can also be added to one of the top corners to help keep the frame perfectly square during manoeuvring and fitting within the doorway. Bracing the bottom at the same width as the top is easiest to achieve using a piece of wood (2x4 inch) cut to the same width as the header. Position the wooden brace 6-8 inches up from the bottom and nail it to the exterior side along the far right and left edges of the trims so that when removed the nail holes are concealed by the frames architrave. You can do this on both sides of the trims/frame, at the same height which will keep the trims perfectly straight. The diagonal brace can also be added in the similar way, using a framing square to hold the brace at a 90° angle whilst nailing it.

Levelling the Header

Position the door frame in the doorway opening and check the header is level using a spirit level. Regardless of whether level or not, at this point it makes good practice to mark one of the sides using a pencil, so if removed to make adjustments your able to quickly determine which way round to put the frame back in. If the headers level then you’re ready to move to the next step but if it isn’t then place wedges under the side of the frame that needs to go up until it levels out. After you are sure the header is perfectly level, measure the distance from the bottom of the trim to the ground on the wedged side of the frame. Once you have measured and checked your measurements, remove the frame and cut the length off the bottom of the opposite trim, and when returned to the opening the header should now be level.

Fixing the Frame in Place

It’s important to get both sides of the frame fixed in place as straight as possible. If the doorway is within a section of studwork then drill 4-5 pairs of holes in each trim, that are evenly spaced out along the full height of the door frame. If fitting to a brick wall then space the drill holes out as equally as possible making sure that they are also positioned to fall in the middle of the brick to avoid cracks. Next, ensuring that the frame is lined up, tighten the screws on the hinge side first. Once you have tightened all screws use a spirit level on the internal face of the trim to check that it is running straight, and repeat on the other side. You may need to use wedges of wooden packing to fill hollow areas, along within loosening off and tightening screw pairs individually to achieve perfectly straight sides on your door frame.

Once you have fitted the door frame you can move on to fitting new door hinges to your doors, read our article on how to fit door hinges or buy door handles UK from our wide selection of modern door furniture ready for once your doors are hung.