^^^ This.
Don't forget those shiny granite countertops as well...
Don't forget those shiny granite countertops as well...
Finishing Basement - Insulation Question
- Thread starter JoeRider
- Start date
Just went through redoing a basement, I used a reputable contractor and the spray foam was fine.
I believe that the spray will form its own vapour barrier if installed correctly.
I can't see batts forming a complete seal with each other by butting them together.
We started out using a hack contractor to waterproof the outside, he was a friend of my brother-in-law at the time, then ended up having to fire him and hire someone else to finish it properly. After that we found some reputable people to dig out the basement floor and re-pour it - we had an effluence, waterproof the insides of the the walls, install a sump pump and refinish the walls.
I believe that the spray will form its own vapour barrier if installed correctly.
I can't see batts forming a complete seal with each other by butting them together.
We started out using a hack contractor to waterproof the outside, he was a friend of my brother-in-law at the time, then ended up having to fire him and hire someone else to finish it properly. After that we found some reputable people to dig out the basement floor and re-pour it - we had an effluence, waterproof the insides of the the walls, install a sump pump and refinish the walls.
Old can also be as crooked as a dog's hind leg. Some houses were built piece-work to keep costs down.
I reno'd the basement in a century home a couple of years back. I did basic research and worked as an electrician at the time so asked a lot of questions of the builders I knew. I ended up going with wood framing stood about an inch from the concrete wall. Covered the back side with tar-paper top to bottom, used roxall moisture resistant batts for insulation but left about a foot un-insulated at the bottom and then covered with 6mm poly top to bottom. Sealed the joist cavities with same 6mm and tied it all in with tuck tape. My understanding was the foot of open space (and your concerns about R value) were to help keep the earth around the building warmer and from frost building up against the house. Basement is still warm and dry!
Bingo.
I just finished a minor repair on a new "English Manor" type home. When finished it will appear to be ready to weather the centuries. Underneath it's all glue and sawdust. But it will have granite counter tops.
Xhumeka
Well-known member
I was interested in re-doing a basement room in our house a few years ago, and saw one of Mike Holme's shows where he said this is "THE BEST way" to insulate a basement. I wanted to make sure I kept the video for when I re-did our room, so I uploaded the relevant part to youtube:
http://www.youtube.com/watch?v=4jSuWbdJy5A
Regardless of whether or not you think his way is the best way, it's interesting to read through all the comments - lots of opinions and I'm still not sure WHICH way is "the best".
http://www.youtube.com/watch?v=4jSuWbdJy5A
Regardless of whether or not you think his way is the best way, it's interesting to read through all the comments - lots of opinions and I'm still not sure WHICH way is "the best".
FLSTC
Well-known member
I'm currently finishing the basement in my 8-year-old house. I removed the fibreglass blanket, glued 1" EPS board (foamular) on the wall (taped over joints), and spray-foamed the rim joist. I used Delta FL on the floor - this tuck-tapes to the foam board on the wall, with 7/16" bluwood OSB on top. The foamboard doesn't fit perfectly to the concrete wall - with the minute gaps, any moisture can make it's way to the floor and under the Delta FL to the drain. I'm using bluwood 2x4 framing - bottom plate on top of the subfloor. I'll install Roxul insulation once the electrical is done with drywall on top (fire rated near the furnace and cheap stuff elsewhere, except the bathroom which will be greenboard and concrete board in the shower). No vapour barrier. I'm going with the theory that the 1" foamboard will be enough to provide a thermal break from the inside to the concrete wall, while a lack of any other vapour barrier will allow any moisture to be able to evaporate on it's own. Base plates and subfloor sheets are secured to the floor with tapcon screws. Bathroom and laundry will be tiled - will use Ditra underlayment under the tile. I have a 36x60 shower base (latticrete) - will get custom glass/slider done later.
FWIW I rebuilt a figerglass boat (Glastron) and when I stripped out the sole plywood (Rotted) the closed cell floatation foam underneath was totally saturated. So much for 100 percent waterproof foam.
Also if you make a house completely air tight you might end up with poor air quality if you don't allow some deliberate leakage.
Also if you make a house completely air tight you might end up with poor air quality if you don't allow some deliberate leakage.
IMO this is almost a perfect method, and not cheap either. The foam is the thermal break your looking for, however 6mil poly vapour barrier should still be used on the warm side of the insulation if your using Roxul, the rock wool will still accumulate moisture and be less effective.
ALL houses are built piecework...even custom. One of the worst trades out there for quality is one of the most important the FORMING CREWS who do the foundations. Have seen many new homes totally sitting on wood shims supporting the framing due to wavy out of level concrete sills and bulging out of level walls due to the weight of the concrete during the pour pushing out the forms.No vibrators used anymore just pour and hope for gravity to do its thing plus add too much vino and bobs your uncle
Thank you, for this detailed info..
ALL houses are built piecework...even custom. One of the worst trades out there for quality is one of the most important the FORMING CREWS who do the foundations. Have seen many new homes totally sitting on wood shims supporting the framing due to wavy out of level concrete sills and bulging out of level walls due to the weight of the concrete during the pour pushing out the forms.No vibrators used anymore just pour and hope for gravity to do its thing plus add too much vino and bobs your uncle
Yup and the wood framing crews are just as much to blame for accepting the condition
FLSTC
Well-known member
A couple of photos of my work -
Foamboard on wall, delta fl underlayment, and bluwood osb subfloor:
My first wall:
You can see the sprayfoam at the top of the wall (rim joist).
Yes, this is expensive but doing your own kabour, the materials difference is not a big deal. I'm not sure if you'd find a contractor do do all of this - the folks we talked didn't want to do the foamboard and another quoted another $30k for the subfloor.
Foamboard on wall, delta fl underlayment, and bluwood osb subfloor:
My first wall:
You can see the sprayfoam at the top of the wall (rim joist).
Yes, this is expensive but doing your own kabour, the materials difference is not a big deal. I'm not sure if you'd find a contractor do do all of this - the folks we talked didn't want to do the foamboard and another quoted another $30k for the subfloor.
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Personally, I try to keep the drywall up off the floor (by feet if possible) in basements. Basements have a habit of getting wet and drywall wicks the moisture right up the wall. Using something like paneled wainscoting or beeadboard for the bottom row of sheathing isn't expensive and allows for easy replacement. No idea how code feels about this, but I have had to help fix a few basements that were destroyed by 4" of water or less and I would hate to have that happen in my house.
Another vote for vapour barrier in your system. a) I wouldn't expect 1" foam to have the dew point inside it (I expect it will be in the Roxul) b) it's not a vapour barrier
From Owens Corning:
1” FOAMULAR® sheathing actually has a vapor permeance (1.1 perm) that is higher (passes more water vapor) than the commonly accepted definition of a vapor retarder (1.0 perm), and, higher than ½” OSB (0.70 perm), commonly perceived as an acceptable sheathing. So, from that perspective alone, FOAMULAR® passes more water vapor (is less of a vapor retarder) than does commonly accepted OSB sheathing.
well there's the science part to support a vapour barrier. It is spec'd in the building code (which is to help and protect us, not punish us)
some people do. Others are going with bluewood But whatever you use, never put bare wood directly on concrete.
