Dirt in crawlspace under cold room
Hi
I live in Milton Ontario. There is a 400 sq ft room at my Mother’s house that was intended to be a garage 30 years ago and the previous owner changed their minds and made it a living space. There is soil about 1 foot under the floor joists. The room is damp, smelly and cold. My Father went under there years ago and laid 6 mil poly on the soil but that didn’t help much. I believe there is Roxul between the joists.
We don’t usually have crawlspaces in Canada. We want to make it a more comfortable space. I have some mould to remediate on the outer walls (drywall under wainscotting) but otherwise the room is in pretty good shape. I am going to dispose of the drywall and the wainscotting. Any suggestions for the floor and crawlspace? Would placing rigid insulation on the soil and taping it together and to the foundation with Tuck tape make sense (cheaper than spraying foam)? There have been a lot of mice in the past but we seem to have them under control.
Thanks
Dave
Replies
Is the crawl space vented?
Describe Roxul, please--never heard of it.
Roxul is stone wool I think - but could also be fiberglass batts.
BuildingScience.com takes on this question. One detail they do is apply 2" rigid foam board to the underside of the joists and tape those seams, this provides a thermal break and will make your existing insulation more effective.
Also, with that 6mil layer, were the edges ans seams sealed or was it just layed down? Is the crawlspace ventalated?
Link to Roxul website
http://www.roxul.com/home
Some folks will open a post by listing all their qualifications, and asserting their expertise. This is no such post. I lack any credentials, and am almost by definition unqualified to offer advice. Not that such a detail ever stopped me before! Here goes:
Crawl spaces have their uses. Like any method, it has its' advantages and drawbacks. What matters is that you don't try to make a crawl space be anything but a crawl space.
Crawl spaces are not meant to be sealed, or to be part of the 'conditioned' space.
Folks put plastic on the dirt to reduce moisture / condensation issues on the wood framing above. Another element of this moisture control is the venting of the crawl space. The vents also allow for radon (created in the rock underneath) to go somewhere besides into your house.
Your problem is a cold floor. Well, then you want to insulate that floor - not the crawl space.
You can attach insulation to the underside of the framing, or between the joists. Or, you can put a layer of insulation between the subfloor and the finished floor.
You also need to verify that your heating system is doing it's job. You need enough air flow. The ducts need to be sealed and insulated.
Finally, LOOK UP. A cold wall, window, or door will create a draft- one that will wash the floor with cold air. It is simply amazing the difference you can make by adding an inch of foam to a metal door.
Dirt in crawlspace under cold room
Thanks all for replying
I guess it's been established that Roxul is like fibreglass insulation but it's made out of rock not glass.
No it's not vented. The house is built very low to the grade. Hardly any height to do that with.
It seems my Dad put polystyrene foam between the joists (just under the plywood). I'll get underneath to see if he has insulated under the joists. Unfortunately the vapour barrier should be under the plywood subflooring but could also be under the joists. I'm not sure we will get it perfect.
I'm not sure it has nough ventilation. It seems to be 1- 6" cold air and 2 - 6" supplied air ducts. 400 sq ft and almost 9' ceilings.
Maybe add more air flow into the room and vent the crawlspace...
Dave