AS said couple of coats of paint or perhaps pva first coat diluted on both.
Decant paint into container to avoid contaminating rest of paint and dispose of the brush.
I would look at the flooring you need a draft under floor, Do you have bare boards, if so those gaps add up! Hardboard under carpet and underlay for a start with mastic between the skirting and flooring, also board cupboard floors like under stairs.
Sounds like you are trying to use the filling loop to drain. Can you post a picture of the boiler connections?
Best way if you cannot find a drain cock is pick the smallest downstairs radiator turn off both ends, open the air vent and undo the rad connection enough to drain into a bowl. Then...
SDS will not "hammer" when you squeeze the trigger and pull. Try putting a normal hammer drill on the bit and reversing with that. You can try clamping mole grips on the shaft an inch or so from the wall and using a crowbar behind the jaws levering against the wall. Otherwise the only thing I...
Sounds like crappy paper regardless of price.
A thin paper will highlight defects regardless of PTW or normal. Sorry but unless your walls are perfect a textured or at least heavyweight paper is the way to go. I don't know how much is done or needs to be stripped off if not much perhaps using...
It needs supporting if no lintel.
DG firms just don't want the hassle!
Are you using national companies or local established fitters? A local recommended company with a reputation to maintain should give you advice.
I briefly worked for a national company and my experience was that many are on a...
We used to coat them in Synthaprufe (rubbrised bitumen paint) when putting in the carcase back in the late '60s not sure if it is still recommended practice though.
Denso tape is good too but a nightmare to apply in situ against the floor.
Mostly they only rusted at floor level as water laid...
Can;t see the soil pipe hole in the pic but as you say it's 1'5 metres away I can't see it doing any harm, when fitting the old boilers we used to knock out 9"x 9" holes in walls and none fell down.
OK I am not a structural engineer but I would be quite happy to put a brick sized air brick in if...
I would think that removing one brick and fitting an airbrick would be less risk than a 4" hole, normally they are just under the DPC level, if too low any flooding along the path could run under your floor.
Any particular reason you need an extra air brick?
You need to establish the Backset in mm and search Goggle for that size.
Measure from door edge to centre of the hole.
This might help.
https://www.doorstuff.co.uk/p/backset