Jan 27
Is it dangerous to add Foam Board Insulation by knob and tube wiring? How far away would it have to be not to pose a hazard? Or is it possible(and safe) to add some sort of flooring over the wiring and then add insulation? Any info would be great!
I am in the US, a lot of us have it here who live in older houses. We live in a 1920’s victorian.
put fiberglass over it then the foam
knob and tube wiring isn’t,t the best but that is the way it was done then [20,s]
Jan 21
I am going to be building a 10×14 shed when it warms up a bit. I plan to use it as a shed to store my lawn tractor and garden tools but i can see a time in the future where i may want to use it as an escape (i am going to run power, tv and internet to it). I can insulate walls and ceiling later but the floor is something i think is a lot easier when you are building the shed. My first thought was to use fiberglass but i then thought about mice and potential for getting wet being so close to the ground. So i am now thinking about something waterproof which would be 4×8 sheets of foam board.
My current plan is to build the floor out of 2×6’s 16inches on center. I would then build the walls and put them up. Next comes the floor made from a 1inch foam board (laid directly on the floor joists) and then 1/2 inch plywood. This would bring the floor up to the same level as the 2×4 plate at the bottom of the wall so the floor would be level. The 2×4 would take the brunt of traffic thru the door and the floor would take load from the top.
Other option would be to first put down a sheet of plywood, then foam board, then another piece of plywood on top and then build up the door ways with 1x so the floor level matches.
When you build your floor be sure to lay some heavy plastic on top of the ground and use pressure treated lumber for the frame and joists. My suggestion for the insulation would be to use 2" rigid foam and to hold this up you install a 1" square cleat 2" down on each side of the floor joist. That way you can measure between the joists when you get them laid, as wood varies from one board to another, and cut the foam on a table saw to the exact measurement and slip it down inbetween each set of joists. Run a bead of construction adhesive on each cleat before lowering the foam pieces on to them. That way they will stay in one place. At this point the Foam Insulation board should be laying just flush with the top of the joists so you can lay the floor on top of them. I’d use construction adhesive under the plywood on the joists and the foam. I really don’t think you’d like the sandwich, plywood, foam, plywood again. The foam will compress with age and pressure and soon you’d be having problems you don’t need. This way you get great insulation on the floor and good rigidity as well.
Jan 3
I recently framed out a large section of my basement. Half of the framing was existing 2×3s, most likely 20-30 years old or more. The framing in the very corner of the basement, which was I assume had moisture over the past many years, the wood smells pretty bad.
It’s an odd smell, like something sour or rotten. The wood appears to be strong and no mold present, it just smells bad, especially on humid days. I think what I will do is rip out the affected studs and replace with new, but I’m curious of what that smell could be?
Next - for the walls that are 2" off of the concrete walls, I plan to you the polypropylene board insulation.
I’ve read in a few different postings that some guys cut the boards to fit perfectly between the 16" on-center studs and either caulk them in or use that foam stuff spray to hold it in place.
I assume I want to use at least 3/4" between each stud. Any thoughts on this?
Also I’ve checked Lowes and I can’t seem to find what I am looking for. They only appear to have either very thin foam boards or 12" wide pre-cut sections. I guess I need to buy 4×8 sheets of this stuff somewhere and cut it down myself?
Quick note - I have no immediate moisture problems in my basement, no puddling water to be found.
I’m sure there is vapor coming thru the walls, and I’ve painted the walls with some sealer for the heck of it. But nothing too major that I’m going to worry too much over. But that’s why I plan to use the foam instead of anything else.
Thanks in advance for any advice.
The U.S. Department of Energy recommend that:
1 - Extruded (not expanded) polystyrene board be applied directly against the basement wall (no framing or studs needed) and that the gaps between boards be sealed with mastic tape. The idea here is to avoid the use of wood studs directly against the basement walls, because wood soaks moisture and favors mold growth.
The smell that you detected on those studs is mold. Mold smells before it can be seen and way before it starts to actually rot the wood. And it spreads quickly too.
That is why the Department of Energy recommends that they be kept away from the basement walls. In their approach, the insulation boards, sealed in the joints with mastic tape act as a vapor barrier.
After lining the walls with insulation, furry strips can be placed on top of the boards to attach the drywall.
I am adding here a link to two of their issued PDFs on the matter I wouls strongly suggest you look into if you want your basement finishing job to last.
Two more things to consider:
- Keep in mind that the these measures only deal with outside ground moisture that seeps through basement walls. Below grade structures are prone to moisture from more than one source, one of which being condensation. Consider installing a good, energy star rated basement dehumidifier.
- Drywall and wood studs will also not withstand a basement flood or even a plumbing accident.
An alternative to these would be using finished, cement-core, insulated basement wall panels. They are 100% waterproof, non-absorbent all-in-one solutions that won’t get ruined if your basement is under water. They also have the advantage of being removable to access wires and plumbing or inspect the walls, and the cement core gives you walls that are sturdier than drywall, where you can hang book shelves and big screen TVs without needing to look for studs.
