Making a doorway in an existing wall may be necessary if you are changing the use of the room or improving its layout: this is often required as part of the process of converting a kitchen, where fitted units dictate the positions of access and exit doors. As with fitting a hatchway, it is necessary to install a lintel to ensure the stability of the wall itself and any other load which bears on it.

First check whether the wall is nonloadbearing or loadbearing. If the latter, seek approval from the Building Control Officer (BCO). Begin by marking the opening on one side of the wall, then examine the coursing of the bricks or blocks by exposing a small area; move the opening if necessary to align the perimeter with the vertical joints.

The height of the opening should allow for the height of the door plus 9mm (34n) tolerance, the thickness of the soffit lining and a new concrete or steel lintel. The width should be the width of the door plus 6mm (1/4in) tolerance and twice the thickness of the door-jamb lining. Allow a further 12mm (hin) for fitting the lining.

Carefully prise off the skirtings from both sides of the wall. They can be cut and reused. Prop the wall and fit the lintel  before cutting out the bulk of the masonry. Leave overnight for the bearings to set hard. The next day, starting from the top just below the lintel, chop out individual bricks, using a club hammer and bolster chisel. At the sides of the opening, cut the half or three-quarter bricks protruding into the doorway. Chop downwards where you can. If the wall is built from lightweight blocks, use a universal hand saw or a masonry saw to slice through the bonding. At the bottom, chop out the brickwork to just below floor level so that you can continue the flooring.

Bag up the rubble frequently in stout polyethylene sacks and stack whole bricks out of the way for reuse. Spray the area with water from a plant sprayer in order to settle the dust.

Fitting the door lining

You will have to fit a timber frame within the new doorway to which you can attach the stop-bead, door and decorative architrave. Make the frame from planed timber 25mm (lin) thick and the width of the wall. Fit the lining to the sides of the opening with galvanized- metal frame cramps (1) mortared into slots cut in the brickwork, or fit wooden wedges in the mortar joints and nail the frame to them (see diagram (2) left).

First locate the positions of the studs, then prise off the skirting. Mark out the position for the opening on the wall, then remove the plasterwork. For lathand-plaster walls, chop through to the laths with a bolster chisel and saw them off. For a plasterboard wall, saw through the cladding or use a sharp knife. If there are studs on each side of the opening, cut the plasterboard or laths flush with them. If the position of the hole does not correspond with the studs, cut back to the centre of the nearest stud on each side. Cut one or- two studs to the right height —that is, the height of the door plus 9mm (3/8in) tolerance, the lining thickness and a 50mm (2in) head member.

Level up and and skew-nail the head member to the remaining studs at each end. Also dovetail-nail it to the ends of the cut studs. Saw through and remove the floor plate to the width of the door, plus 6mm (’/in) tolerance and twice the thickness of the door lining. Cut and nail the new studs, which will form the door jambs, to fit between the head and sill. Fit noggings between the new and original stud or studs. Cut and nail plasterboard to fill the gaps between the original wall surface and the new studs. Make and fit the door lining. Finish the surfaces with plaster, fit the architraves and replace the skirting.

Alternatively, cut the cladding from floor to ceiling and refit the studding flush with the cut edge. Mark the width of the opening, saw through the plaster from both sides of the wall then strip the plasterwork and knock out the exposed studs and noggings. Cut the floor sill level with the plaster and remove. Drive the studs into the cut edges until flush. Nail them at top and bottom. Fit a door-head member between them and a short vertical stud above it. Cover the space above the doorway with plasterboard.

Draw the position for the lintel, allowing a margin for fitting tolerance. Chop a groove around the perimeter of the opening with a club hammer and bolster chisel, then hack off the plaster. Fit adjustable metal props and needles, then cut a slot for the lintel. Bed a concrete lintel in a mortar mix of 1 part cement :3 parts sand on bearings no narrower than 150mm (6in) at each side of the slot, and set level. Pack underneath the lintel with pieces of slate until it is horizontal. Replace loose bricks and fill any gaps with the same mortar mix.