Solar and power wall 3 quote.
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I nailed thin wood slats to the rafters that compress the (batt) insulation underneath so there is a 1-1.5" gap between the insulation and the roof decking.
Rudimentary, but $0.50 per rafter bay . And some awkward positions and time spent.
Rudimentary, but $0.50 per rafter bay . And some awkward positions and time spent.
Burnin Since 1991
Minister of Fire
My house is a cape cod style with a steep front roof and a 3/12 pitch back roof. In the attic where the rafters meet the joists, it is such a small area that I can only get to about 4 feet from where they actually meet. The real issue is that the insulation in the joists reach the roof deck and it looks to me like there is no air gap. It's really close to the area above where the ice dams form. I think I'm most likely have the Mass Save folks (state mandated and paid for out of our energy bills) come in and see how much they want to get the baffles in and add more insulation in the attic. The costs are reduced due to our mandated payments, so it 's less expensive than doing it myself and a heck of a lot easier.
If I had a more traditional home and roof, it would be an easy fix.
My roof is 3/12 too. Front and back. And one section a hip at 3/12.
I got stuck with my head in that corner once between the rafters and floor joists (while spray foaming around the top plate of the outside wall.
I had r19 between the joists and I added r38 on top (90deg rotated, and unfaced). Yes, it needed to be compressed at the outsides. Not r38 anymore then but best I could do.
I guess the eves (18" I think) mean that most of that compressed insulation is on the eves and the proper r57 (19+38) is on the heated part.
It's not easy, but it can be done, if you have long enough arms and are not too big in other directions.
I spent 6 weekends in my attic sealing and adding batt insulation.
I got stuck with my head in that corner once between the rafters and floor joists (while spray foaming around the top plate of the outside wall.
I had r19 between the joists and I added r38 on top (90deg rotated, and unfaced). Yes, it needed to be compressed at the outsides. Not r38 anymore then but best I could do.
I guess the eves (18" I think) mean that most of that compressed insulation is on the eves and the proper r57 (19+38) is on the heated part.
It's not easy, but it can be done, if you have long enough arms and are not too big in other directions.
I spent 6 weekends in my attic sealing and adding batt insulation.
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That's the most important part to insulate really, really well to reduce ice damming. There is usually little vertical room between the roof joists and the ceiling joists where they connect at the wall, and the wood top plates of the wall have little insulating value. I was very diligent about spray foaming this area completely full and they carefully placing rock wool batts in all the areas outside of that, compressing it where necessary. I still have some nicely decorative icicles on my house 8-12" long in the midst of winter, but nothing like other old houses in my area with 5-6' long monsters in some places.
A common problem area. The issue is probably not the insulation touching the decking, but the fact that there is likely a gap between the drywall and the top plate (framing) of that wall. So heated air from the wall cavity is rising up through that gap and straight through that insulation. Framers and drywallers left those gaps intentionally during construction for decades, thinking the house 'needed to breath'. Then when there was a lot of condensation in the attic (from conditioned air going up there), rather than sealing the floor of the attic, they mandated increased passive ventilation of the attic. If that didn't work... put in power ventilation! These were all bandaids to the basic problem: the huge amount of warm moist air rising out of the house into the attic.
A 1/4" gap that is 20' long is a half of a square foot. Imagine having a window cracked open 3" and how much hot air would pour out of it.
Nowadays we know to airseal the floor of the attic underneath the insulation. And then a little passive ventilation will suffice, there are seldom any ice dams, and power venting is not required.
In my 1960 house with a shallow roof, I couldn't reach those top plates either. And I had ice dams. And the roof sheathing would always drip condensation in the winter. That is one of the things I had pros airseal for me in 2014, and I never had ice dams again. I talked to the guy on the project, and he said they have a 'little guy' who specializes in worming into that space and sealing it. Its a living I suppose. I'm grateful.
^^that.
It can require some contortionist exercise, but it's worth it.
It can require some contortionist exercise, but it's worth it.
Burnin Since 1991
Minister of Fire
Well, I'm not as agile as I used to be. I am coming up on the 46th anniversary of my 21st birthday. I'm in decent shape, but I know what I can and can't do. I will leave it to the experts. We had the family house on cape cod and had the mass save program install blown in insulation into the ceiling of the garage (floor of 2 bedrooms) and in the attic and it made a huge difference.
Hopefully they have a little guy that can work those spaces too.
Hopefully they have a little guy that can work those spaces too.
That the wisdom speaking that those years have provided.
(I had a few swear words when I had to rotate my torso to fit between the rafters, keep my hips on some pieces of plywood, stick my head in a place that I could see something, and then stretch my shoulder joints to the max to spray with my spray can (in the right orientation....). And then I couldn't figure out how to get my noggin out of the hole it was in. Took a break, thought a bit, and 10 mins later I was out...)
With blown in, it's especially important to guard soffit vents from being covered.
Yeah, on my remodel I was that "little guy" when the insulating crew was installing the soffit vent baffles prior to the 2" air-sealing layer of spray foam on the attic floor (I did the blown-in insulation myself). The guy who was supposed to do it was botching the job because he was too big and honestly either didn't know what a good job was or didn't care. So I just borrowed his staple gun and crawled in and did it right. Good thing I was there to watch the work being done. I'm <150 lbs.
This is the same crew that left lots of spray foam out of obvious empty pockets even when I marked in white chalk on dark larch framing members "spray foam goes behind this". And don't get me started on the rework they had to do in one of the closet sloped ceilings where they installed baffles so poorly I only had an effective 1" of foam in parts of the ceiling (which I had them come back and tear out and redo).
I think this crew was a typical insulation crew - not the worst.
Lesson - insulation quality is something you should know and supervise for quality and just do all the final details yourself because insulation crews will just never do them right.
Burnin Since 1991
Minister of Fire
I have a smaller friend. He owes me.
Mass Save requires an inspector to check the crews work. But I get it. I will find someone I trust to help me with the baffles and spray in the ends and let them just do the insulation placing. (Blown in or otherwise).
My first rule for insulation work done in any house I own or am going to live in is to trust no one. It sounds like you know what a good job is and have attention to detail to get it right. If you do the math on heat loss, 5% of the area left uninsulated will result in an almost 50% drop in the overall R-value for the house. No contractor understands this - they all think that 5% uninsulated results in 5% drop in R-value.
Also, it is really, really easy to do the blow-in insulation yourself. Most home centers will rent the blower for little money or give it to you for free for a day for the cost of all the cellulose bags. You just need a friend on the ground to feed it into the blower while you work the hose in the attic. I had the foam crew just put in a 2" layer in the attic floor to air seal, then blew in cellulose on top of that. I made sure I got the depth I wanted after accounting for future settling. It was easy to do - no real skill or learning required. By the time you take a day off of work to make sure the unskilled laborers that show up to do the cellulose installation are doing it right you might as well just do it yourself.
Also, buy one of those professional (reusable) spray foam gun attachments with a can of cleaner and then a bunch of the big cans of foam. I probably used 40 big cans of foam after the foam insulation crew was done.
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