In the event that it is a load-bearing retaining wall, or if you are unsure, it is critical to seek the advice of your local

specialist building inspector first.

Draw the new opening on the wall and remove any skirting. Work out the proposed door width, including both legs of the lining, plus 25mm. Evaluate and mark out the height, allowing for the lining plus 10mm tolerance.

Sketch out the placement of the lintel, allowing for about 15mm for the bedding and packing under each end. Place dust sheets on each side. Cut away the plaster as neatly as possible. Cut a hole in the middle of the entry, about 150mm above where the lintel will be, making use of the drill, then the hammer and bolster. Thread the needle through. Support it on each part, 500mm from the wall with the adjustable props set down onto the scaffold boards.

Cut out the slot for the lintel and place it, bedding it up with hard mortar combined one part cement to three parts fine sand, loading it tight with pieces of slate inserted into the mortar. Leave overnight.

Chop out the other parts of the opening. Drill holes at intervals down the edges. Commencing at the top and slicing down with the bolster, slice out and get rid of the bricks and part bricks. Light in weight blocks can be sawn. Use a hand-held spray to prevent the dust going everywhere when the hole is cut, clear up the dust before planning on to the next phases. Take away the props and needle.

Help to make up the lining by hanging the two legs to the head, allowing for 2mm all around for door clearance. Otherwise, use ready-to-assemble linings with the head rebated to receive the legs.

Fix the latch leg to the brickwork by drilling through the lining into the brickwork and using the frame fixings. Examine for level in all planes, taking the leg out with slate or hardwood where required.

Deal with the hinge leg of the lining in the very same way, using wooden-packing pieces and modifying for top to bottom in all planes and also level on the head. Fill in at the rear of the lining with mortar and allow to set. Refit the skirtings, ceasing at the stage where the architrave will start. If you need to come up with the plaster, do this before fitting the architrave.

Make good the needle hole with some of the older bricks and patch up the plasterwork. Mitre the sides of the architrave using the mitre block. Add the architrave to the lining to mask the cut-aside plaster and the join among that and the lining.

At this stage your finished and you can pat yourself on the back for a job will done.

For a job of this type you will first need:

A hammer

A club hammer

A lintel (pre-stressed cement with 150mm bearing on each end)

Several pieces of slate

2 short scaffold boards

Sand and cement

Ready-to-assemble doorway linings or 25mm x wall thickness planed all round wood for door lining

Completely new architrave

Metal sleeved frame fixings

Packaging pieces (hardwood offcuts)

2 flexible steel props

150mm x 100mm wood support needle, 1.5m long

Lost head nails

A further masonry bit suited for the frame fixings

A spirit level

A mitre block

A bolster

An electric drill with a 20mm masonry bit 150mm long

A saw