I have been googling this and most advice scarily seems to be to seal up airflow bricks and add a waterproof layer on dirt floor of crawl space as well as the insulation. I agree with Piglet John that its important that the underfloor space is very well ventilated.
PigletJohn does the insulation you suggest still allow some air/ water vapour permeability? Our 3ft deep crawl space is very dry but our floorboards can be quite draughty. My dad (rest his soul) swore blind that insulating under the floorboards was a recipe for rot but is the method you suggest likely to be okay? So long as not plastic backed so still air and water vapour permeable to some extent it should be ok? I had just been leaving it (and shivering) til I found this thread!
if you can clamber undernath, you can stuff loft insulation quilt round the edges of the room between the joists and the wall, and roll lengths of it between the joists. It will provide insulaton and blot draughts. The quilt will tend to flop down so it is usually held in place with garden netting stapled to the joists. I would definitely use a mineral wool roll that is made with Ecose which binds the fibres and prevents shedding of fibres and dust. The treated wool is brown not yellow and is made by Knauf but also sold under some retailer own brands. Look for the name Ecose on the packaging. I would not touch anything else now. Use a dust mask, goggles and gloves anyway as it will be dirty and dusty under there. Clear up any rubbish under the floor, especially scraps of timber that can harbour rot.
It is of course far easier to insulate between the joists from above while the floor is up.
It is very important that the subfloor space is well ventilated using airbricks on at least two sides of the house so there is a detectable airflow. An airbrick every two metres is not too many. Clear dirt and cobwebs out of existing airbricks.
We could take it up in the alcove if we only needed a hatch. It clicks together so I think we'd have to go for an edge and the flooring in the alcove doesn't go under the skirting - the meters made it impossible. I'll have a look into floor insulation, thanks :-)
We could get under the floor in theory, but it would mean taking up the bamboo flooring first and to do that take off all the skirting - and make sure the flooring fits when it goes back down. Tbh I'd rather find another way of addressing the problem. If there is one!
Mum2Fergus - Have found the stopgap website and it looks like it could be just the thing for the skirting board draughts - thank you
jazzcat28 - Did your insulation go into a void like ours? Did any of it come up through the floor or the gaps in the skirting (if you had any)? I like the idea of the insulation being fired into the void, but on the EST website it states that the whole wall has to be done and all gaps filled so I'm now imagining it bulging up into the living room and our having to do more decorating. Though to be fair, the website is referring to it being used to fill wall cavities not the void underneath a room, so maybe it's different.
I have a Victorian house and cavity wall insulation helped a lot. They drill little holes in the cement between the bricks and spray foam in. Can't tell it's been done from the outside but it's warm inside. We paid £160 for a 3bed semi 2 years ago using various grants
We have recently moved around our downstairs rooms to put the living room at the front of the house and the dining room next to the kitchen. On paper it seemed to make sense. We knocked down the wall between the hallway and front room to make it seem bigger and as we have small children we put down bamboo flooring with a rug on the top - it looks beautiful :-)
It is however freezing cold. There is a large void under the front room as there are steps up to the front door and no cellar. We removed the skirting to lay the flooring and put them back on afterwards. The draught from under the skirting is icy - I guess it comes through the air bricks at the front, through the void and up through the gaps and we've really felt it this week.
Does anyone have any suggestions as to what we can do about it. We are not keen at all on taking up the flooring given that we've not had it laid long and it might not go back down very well -and there is no way we're buying new flooring! I was thinking about cavity wall insulation. We haven't got cavity walls (Victorian terrace) but could we remove a brick and put it into the void? Is this a daft idea?! My dh suggested polystyrene balls to fill the void but I'm not sure if he was serious - it must be at the very least a fire hazard. My MIL suggested putting something against the air bricks outside when it's really cold, but obviously it's not a permanent solution. We could theoretically fill the gaps under the skirting if there is such a thing as a filler which lets the floor expand and contract. But then, it's not just the draughts, the floor itself is cold to the touch, though where the rug covers is fine.