If you want to create a new opening for a doorway in a brick wall firstly you need to ascertain if it’s a single skin (usually an interior dividing wall) or double skin (exterior wall) and whether the wall is load bearing. On load bearing walls you will need to install a lintel or steel beam above the opening, on both inner and outer skin (if a cavity wall). On a cavity wall you will also need to fit cavity closers (the plastic ones are best), this is to prevent water penetration between the two skins, when the new door lining has been installed. The common construction of a cavity wall would be brick on the outer skins and light weight blocks on the inner skin.
How to open a doorway in a brick wall
Mark the position on the brick wall where the doorway is to be located. Always measure the location of the opening from both sides, as well as from the top down. Remember - measure twice cut once.
Using the spirit level and chalk line, mark the two vertical lines on the wall (if it is an external cavity wall, you only need to mark the inner wall). Join across the top for the horizontal line to create the shape of the doorway. Allow enough extra height over and above the door frame size for the steel beam (if it is a load bearing wall).
Using the power drill and long masonry bit, drill a hole in each corner of the chalk line (top and bottom), through to the other side of the wall (both skins if a cavity wall). Where the holes are found on the other side of the wall, join using a chalk line and the spirit level to create the horizontal and vertical lines to match the inside.
Make sure you are wearing eye protection, ear protection and gloves. Using the disc cutter and 15 inch blade, cut along the two vertical lines on the outer skin (best practice is to go from the top down). Cut a few inches past the top of the horizontal line drawn. The disc cutter won’t cut all the way to the floor, so the last couple of inches you will need to use the hammer and bolster. With the disc cutter now go along the top horizontal line, again passing the vertical lines by a few inches.
If you are cutting a single skin wall, you will now have a cut out of the doorway shape, next step is to remove the bricks. If it is a cavity wall, run the disc cutter back in the same groove until you go through the second skin (if the blade you are using isn’t deep enough to do this you will need to repeat the process on the interior skin).
The supporting wall will need the steel beams in place prior to removing the brick or block work below. You will first need to carefully remove two courses of bricks below your horizontal cut and give a bearing of at least 4 inches on each side. Slide the steel beam into place, ensure it is level and then dry pack to ensure a tight fit to the brick work above (repeat for the second skin). Use a quick drying mortar to pack around each end of the steel beam. You can now remove the brick work from under the steel beams. This is best done starting from the top and taking one or two bricks at a time using the hammer and bolster. The block work skin you may have to split the blocks using the hammer and bolster to remove them, or stitch drill until the blocks become loose.
Your doorway is now open to have the door frame installed.
Check the dimensions of the door frame to ensure the opening is the correct size to include the door lining.
Check with local authorities for building regulations. When working at height, always use an approved scaffold or tower and if possible a safety harness. Always use power tools in a correct and responsible manner, ensuring the appropriate safety gear is worn. Prior to drilling or cutting check the location of any electrical cables or pipe work that may be buried in the wall.