Hi, I had an energy assessment done in my home and when the attic was inspected there’s some onld 2 inch paper enclosed insulation and batt insulation over top of it. I was told by the assessment inspector to remove the paper insulation and put down the batt between the joists and blow additional insulation over top to get added R value.
The old batt does not have a vapour barrier paper. Does this matter?
I started removing the old paper insulation and inserting the batt and am about 1/3 done.
How important is it to have a vapour barrier between the house ceiling / attic roof? Any comments are appreciated. I live in Toronto, Canada and suggested R value is R-49 / 50.
Domenica
Replies
Here in southern Minnesota, a little north of you. Our home does not have a vapor barrier in the ceiling, nor do most of similar vintage (mid-70s). Doesn't seem to be a problem.
Vapor barriers are more critical in walls, or in the narrow spaces of cathedral ceilings.
Unclear what the old "paper-enclosed" insulation is. I'm guessing a sort of shredded paper insulation from the 50s, perhaps? Not clear that it needs to be removed.
If possible, blow in cellulose rather than fiberglass. Better performance all around, but, oddly, it's often hard to find someone who does cellulose.
Oh, and make sure your eave venting is adequate before you blow in more insulation, and make sure that chutes are installed to keep the eave vents open.
Attic insulation w trusses
I'd like to add more insulation to my attic, but I don't know how to get to the ventilation chutes to secure them (they appear to be coming loose, some of the corners are sagging), and how to get around in the attic in general. The roof is built with W trusses, 24" on center. There is currently 12" of loose fill fiberglass. If I crawl on the fiberglalss, won't I compress it and reduce the R value? And there isn't enough headroom to crawl to the chutes without lying face-down in the fiberglass.
What's the best way to get around in an attic with trusses in the way?
mms
What's the best way to get around in an attic with trusses in the way?
Hire the insulator to do the prep. Make sure they are reputable and secure the old chutes or install new.
That job sucks in even the best situation.
One other thing necessary is to seal any penetrations well (not just blow insul over) in those exterior and interior walls. This will keep warm moist air from making its way up into the attic. Make sure all bath vents are taken to the outside, not must dumped up near a roof vent or laid out over vented soffit.
What's the best way to get around in an attic with trusses in the way?
Get two sticks of 2x6 or 2x8 and anchor them edge-up to the tops of the trusses about 22" apart. (You can "toe screw" them or use some sort of framing anchor.) Then cut 2x4 pieces of plywood or OSB and lay those on top, securing "lightly" (so they won't slide around but can be easily lifted if need be). Make a catwalk in the attic this way for most of its length. This will require that you compress or rake away a little insulation, but not enough to cause a problem.
Then you can use a piece of lumber about 2.5 feet long and drop it in the "crotch" of two adjacent trusses. A plank from the catwalk to this piece of lumber will let you crawl out fairly far.
What I did for the chutes was to get some 1x2 pieces. I think in my case I figured they needed to be about 7 feet long to be short enough to maneuver in the attic (my trusses are 24 feet wide). Make a jig to hold two of these on edge about 22" apart. Staple a 24-26" piece of corrugated political signboard to the edges, lapped over both sides of the 1x2s. Have the sign begin 6-8" from one end and continue 5 feet or so. Then add a small narrow piece of the signboard trimmed to just cover the 6-8" section. Stick a short piece of 1x2 flat under the joint between the two pieces of signboard and staple it in place.
Carry one of these things into the attic, position it with the 6-8" stubs over the outer wall header, signboard down (rake away the excess insulation first, using a childs garden rake or a "shrub rake"), and then lift the other end up to be flush with the top chords of the trusses. Secure the top ends of the 1x2s to the trusses with a couple of DW screws. (If you then need to go higher with the chute you can probably just staple signboard to the trusses.)
I don't know why someone doesn't make a commercial product like this. I can envision a metal frame with hinged struts between the sides and something like Tyvek for the surface. Slide it out to the rim, expand the struts (maybe with a pull chord) to stretch the Tyvek tight, and then lift the thing up. At the top a couple of toothed clips would engage the truss top chord to hold the thing up.
attic crawling
What I did was go to Lowe's and had them rip several sheets of OSB into 16" duckboards, pushed them up through the hatch, and then laid them permanently across the joists. I have batts on top, so I just pushed them out of the way temporarily and then laid them back on top of each board (between the joists is loose fill). You could do something similar and possibly replace the loose fill above the OSB with one R-30 batt.
Now when I need to get up there I roll back the batt on top of the boards and get back and forth relatively easily.
The OSB cost maybe $20 altogether and the cuts were free.
Attic Insulation
The walls in my home, which was built in 1973, in Kansas City had 2" of rock wool in a paper enclosure. I'm pretty sure it's the same as you described. When I resided my house a few years ago, I tore out the old insulation and replaced it with fiberglass batts and am glad I did. Based on my experience, I would recommend the same as the inspector: just tear it out and re-insulate. It was a fast, cheap and easy way to get some insulation in the walls and the ceilings, but not very effective. The R value is low and, in the event of a fire, the paper will burn very quickly.
Fine Homebuilding had a good article (I believe it was in the latest issue) on blown fiberglass vs. blown cellulose in an attic. It was very informative. I would recommend this over the batts. Blown in insulation fills in nooks and crannies much better than batts. I installed fiberglass batts in my attic. If I had it to do over again, I'd blow in fiberglass or cellulose.
I will defer to others regarding the vapor barrier, since you are so farther north than we are. I know Fine Homebuilding has had many articles on this subject over the years. I'm sure you could find good info on your climate in their past articles.
I saw an episode of This Old House in which they insulated an attic to the top of the ceiling joists. They then laid plywood over the joists to provide a walking surface. Do any of you know if more insulation could then be installed over the plywood? You could then moveit out of the way as you are trying to manuver around the attic and replace it as you work your way back to the attic access. Just an idea. Do any of you have any input on this? Good idea or bad idea?