Air bricks are easy to replace but it can be a bit messy - broken bricks, mortar, dust and wall insulation flying around. So take precautions to place down a dust sheet inside to catch this. Also don't forget to wear the apporpriate P.P.E. We will ,as usual, pressume you have taken the necessary health and safety precautions and give you a breakdown of the job.
Remove old cover inside home.
Place new inside sleeve up against the hole, level, then trace around with a pencil.
Stitch dril slightly outside the marked area to allow "wiggle room".
Knock out this stitched hole with a hammer and masonary chizzel.
Knock out the outside hole so it is flush with the inside.
Insert vent sleeve.
Put on inside and outside cover and seal with sealant (silcone, decorators cork your choice.
If the air brick is serving an open flued appliance(s) the appliance(s) must be check by a CORGI registered gas engineer to see if they have been affected.