Would anyone be able to give me an idea of the cost involved in putting a vent in an external wall?
There are none in our 18 year old house and mould has become a bit of a problem. Is it simply a case of knocking through the wall and tidying up afterwards or is it more complicated?
hire a rotary hammer action drill with a 4 inch bore from any tool hire company.Can't be any more than 50/60 per day.If your house has a cavity with insulation then drill from the outside in.Bit more mess inside but at least insulation won't be pushed away from internal wall.
drill a thin diameter pilot hole from the inside out and then drill the main holes from either side with the core bit as previously mentioned - minimal mess alternatively drill lots of small holes and chisel it out - harder . bridge the gap with some 4inch soil pipe you can seal around it with foam or cement etc. vent kits can be bought to cover the ends.