1947 Cape Cod Attic Insulation Advice Needed

Discussion in 'HVAC Heating & Cooling' started by lordoftheflies, Jun 29, 2019.

  1. lordoftheflies

    lordoftheflies Member

    Joined:
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    Location:
    NY
    Hello,

    I am in the midst of a complete bathroom gut on the top floor and have everything down to the studs. I'm actually at the point where I'm about to close up the walls.....

    So the problem is the insulation (and the overall workmanship in this house) is terrible. Most of the walls have a super thin 2" foil backed insulation that literally does nothing. Anyways, I popped my head up into the attic area (between the bedroom ceilings and the roof) and there is minimal insuation that doesn't even cover the 2x4 rafters. Some of the rafters are 2x6 but I'd say 2/3 of them are 2x4 (workmanship, cough, cough).

    There are no soffit vents. I only have a vent on the side of the roof that's about 12" square on both sides of the house.

    Here's a quick video I did scanning the entire area.



    This is what I'm thinking as a plan. Please feel free to correct/suggest/criticize/whatever you see fit.

    1. Since I have the ceiling exposed, I can climb up above the ceiling of the top floor and get a whole bunch of unfaced R-30 and lay it perpendicular on top of the existing rafters. Maybe something like this that I can get at the box store. I could use a 3/4 24" piece of plywood as a temporary mobile floor. I'm almost 300lbs so it might get a little sketchy up there.

    https://www.homedepot.com/p/Knauf-I...nsulation-Roll-15-in-x-22-ft-613430/303654016


    2. Install faced R-13 in the ceiling of the bathroom on the all the rafters then lay R-30 unfaced on top of that perpendicular as well.

    https://www.homedepot.com/p/Knauf-I...nsulation-Roll-15-in-x-32-ft-524187/303648136

    3. I'll have to cut an access hole and frame up a hatch so that I access it from the hallway.

    4. I also have knee walls that had insulation installed incorrectly by a contractor friend. He installed batt insulation with the face exposed. I believe the face should be closer to the conditioned space not the crawl space. I can remove those and install some 2" foam boards and seal with fire retardant foam. Maybe I should double up the boards? If so they would protrude from the 2x4 slightly......

    https://www.homedepot.com/p/Owens-C...ared-Edge-Insulation-Sheathing-52DD/202085962

    I have 5 interior mini-split units with 2 exterior units. 1 for each bedroom and 1 larger unit for the living room. The bathroom will have a surface mounted electric heater.

    Thanks in advance and here's a link to my bathroom remodel.

    https://terrylove.com/forums/index.php?threads/complete-bathroom-remodel.70120/
     
  2. lordoftheflies

    lordoftheflies Member

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    NY
    Another idea is to remove the existing insulation that you can see in the video, seal all the joints with spray foam in a can, install new R-13 unfaced batts, then lay the R-30 perpendicular on top of it. Since the attic space is not used I will not insulate under the roof itself. In the winter I get water damming a lot and I can see the snow melt off of my roof way faster than any of my neighbors who have updated homes.
     
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  4. WorthFlorida

    WorthFlorida Broad-Wing Hawk

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    I also would remove the old insulation and you can go with blown fiberglass or batts. Just be sure you install rafter vents all around since the ticker insulation will block air flow from the soffits. Climbing around attic space many times and worrying about compressing the insulation and going through the ceiling below, I would tack down some 3/4" plywood around the attic opening and in any direction you would think you may need to get access too. FYI...the few recessed light cans must be rated for Insulation Contact. Though you may use LED light bulb, the can may be rated up to 90 or 120 watt incandescent, someone someday may put in a 90 watt halogen.


    (https://www.homedepot.com/p/Owens-C...-Baffle-Proper-Vents-70-Pieces-70RM/204853491)
     
    Last edited: Jun 30, 2019
  5. lordoftheflies

    lordoftheflies Member

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    Thanks worth but I'm pretty sure I don't have vents because I have zero overhang and the gutters butt right up to the side of the house. I can't see any vents from the outside of the inside. So that means I have an unvented roof, correct?

    I installed the cans and theu are IC rated thanks. I also have led trim/bulb combos in there.
     
  6. WorthFlorida

    WorthFlorida Broad-Wing Hawk

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    All attic space should be vented. If you have a typical cape cod style gable roof, then there are walls on both sides of the attic to install louvered vents, one on each side.
     
  7. lordoftheflies

    lordoftheflies Member

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    Yes, I have the louvered vents on each side of the attic but not soffit vents. Doesn't that mean I don't have to worry about where the insulation meets the roof and there don't need rafter vents?

    And yeah, that old insulation looks pretty useless so it makes sense to just remove it, seal the joints with foam and then install fiberglass insulation. I don't need faced insulation correct? That would seem a bit useless since I'll be sealing every cavity with spray can foam.


    2019-06-30 12.18.48.jpg 2019-06-30 12.18.59.jpg 2019-06-30 12.19.16.jpg
     
  8. Reach4

    Reach4 Well-Known Member

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    Is your attic roomy? If so, you could consider turning the attic into "conditioned space". Not cheap, but it gets you a lot of clean storage. If you would be weaving in and out of trusses, then it would not be worth while for storage. The conditioned space is more efficient if you have attic ducting.

    If you don't do that conditioned space thing, I would have a roofer install a lot more vents.
     
  9. lordoftheflies

    lordoftheflies Member

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    No, it is not roomy. I can't stand in there. I would have to bring up some small pieces of plywood that act as a mobile floor for me to crawl around and remove all the old insulation and do the work. It's a cape cod so the roof is the 2nd floor. What you see in the video (linked a few posts above) is above the ceiling of the 2nd floor rooms.

    Not sure what more vents would do. I would think the best way would be to install a push fan on one side and a pull fan on the other. At this point, what started as a toilet with no wax ring has literally become a very large can of worms. :D

    Can anyone confirm if I need faced or unfaced insulation in between the joists in the attic? I think I misspoke before and said rafters. I'm only insulating the bottom of the attic - so in between the joists. Which unfortunately for me are only 2x4 because the builders sucked.
     
  10. lordoftheflies

    lordoftheflies Member

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    Of course, now would be the time to install the push/pull fan system before I insulate. Ugh.
     
  11. Reach4

    Reach4 Well-Known Member

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    Your vapor barrier must be on the bottom for your climate because heating predominates. In the south, the vapor barrier goes on the outside, because the air conditioning predominates. The insulation above the other insulation must not have a vapor barrier. Blown in-insulation is popular for adding insulation in your situation.

    Vents let out moisture. They keep the air over the rafters cooler in the summer, so that reduces heat load. In the winter the vents cool the attic to avoid ice dams, where the upper part of the snow melts, but the bottom stays frozen.
     
  12. lordoftheflies

    lordoftheflies Member

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    I'm not sure I understand how installing batts with the face down on the joists will seal. I suppose sealing with the foam first will take care of that but since I'm not exposing the ceiling I won't be able to staple the face.
     
  13. Dana

    Dana In the trades

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    The first and most important thing from a moisture management point of view is to meticulously air seal at the ceiling plane (under the insulation). This includes installing and sealing air dams where any joists go under knee walls, caulking/foaming all electrical & plumbing penertrations of the ceiling/attic floors.

    Low density fiberglass batts are not very air retardent, and need air barriers on both sides of the fiberglass layer to actually hit it's performance numbers. In winter the warmer entrained air in the batts convect with the colder air in the attic space reducing it's effectiveness when needed mosts. It is also somewhat translucent to infra-red radiation beating down from a hot roof deck, reducing it's effectiveness under peak sun. Blown cellulose doesn't have either of those issues, and pretty much always created a perfect fit (unlike batts, where compressions & gap reduce effectiveness as well.) While you could install R30 rock wool after carfully fitting lower density batts between the carefully sculpted to as snugly as possible, it's easier to get it right with blown cellulose. It's fine to blow cellulose over the existing insulation, leaving it pretty much undisturbed other that what is needed for air sealing.

    With blown cellulose pre-stage some depth markers, which can be as simple as strips of cardboard stapled to the joists with the desired depth marked with a heavy marking pen, then when blowing the insulation rake it out smooth as you go with a narrow lawn rake. That reduced the amount of crawling around you need to do in the tight spaces when installing the insulation- the biggest PITA would be installing the chutes that establish the 1" gap to the roof deck. (There are purpose-made heavy cardboard or foam or plastic chutes available at box stores.) The prep work of air sealing and chutes take more time than installing the insulation.

    The kneewalls also have to be air sealed on the conditioned space side, caulking around all electrical boxes and electrical/plumbing penetrations, including any wiring holes in the framing. Access hatches to the attic space need to be weatherstripped and insulated (2" polyisocyanurate foam board glued & cap-screwed to the hatch door is fine).

    With either blown or batt solutions it's important to install something to maintain the code- minimum inch of air between the roof deck and the insulation, otherwise the roof deck's wintertime moisture accumulations that dry too slowly, and raises the rot risk.

    More tips here and here.
     
  14. lordoftheflies

    lordoftheflies Member

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    NY
    Thanks for the all the info @Dana.

    I'm in NY. Zone 4. Requires R-49. I think the existing insulation is R-3, if that. :D I also have almost no insulation in any exterior walls of consequence except for one room it seems.

    If I get R-13 faced for between the joists in the attic then lay R-38 unfaced on top of perpendicular, that gets me to theoretical R-51. That, I should think, will make a huge difference compared to what is happening now. My heating bill in the winter time is like $650/month Dec-Mar.

    The attic area is small enough that I think it would be more cost effective for me to do everything myself....and I don't have the budget to pay someone to spray foam and I don't trust anyone to do a good job of sealing the cracks in the joists, electrical connections, etc. Plus I need to lose weight so working up in a 100+ degree attic will do me some good. I have a friend helping me on Tuesday. Knee pads ready, 24 cans of Great Stuff (gap and crack, way cheaper than the door and window). I might need to get another 24 cans but I'll see how it goes.

    I don't need the knee wall areas for storage so I think I'll stick to removing the existing batt that was installed backwards, sealing all gaps on the kneewall with spray foam, reinstalling the batts with the faced side towards the conditioned space, and maybe even covering the kneewall then with 2" foamboard and sealing the seams with foam or tape. I can also leave the batts that was installed in the crawlspace on the rafters and install foam board on top of it, sealing the seams as well.

    Your last paragraph regarding the 1" gap - are you talking about where the rafters meets the joists in the attic? Are you suggesting that I install something like Raft-R-mate at the corner since the R-38 will be piled up pretty high there?

    Also, the word "meticulous" cannot be used to describe anything the original builders (or anyone after for that matter) did to this house. I've discovered nothing but ridiculousness - wall plates completely cut out in order to run central ac ducts, wires that were spliced with no wire nuts, 2x4 scraps that were used for door frames, a 2x8 joist notched for the toilet connection down to.......1", and the list goes on.
     
  15. Dana

    Dana In the trades

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    They don't generally enforce R49 in retrofits even when you pull a permit for the work. But how deep are the rafters in the cathedralized ceiling section, and what insulation is in there (if any) in the rafters?

    Leaving the existing batts in place and installing R13s over them (compressed, if necessary) will deliver a higher R than R13s alone. At 3.5" of loft an R13 is delivering R3.7/inch. But if compressed to 2.5" it delivers R4/inch. Kraft faced with the facer toward the attic side is fine, and leaving the foil facers on the old stuff oriented upward is also fine, just make sure it's tucked in at the edges and ends for a complete fill, no gaps. A pair of R13s stuffed/compressed into a 2x4 bay would deliver about R16.

    [​IMG]

    Kraft facers are "smart" vapor retarders, and become vapor open if there is ever sufficient moisture to support mold. Foil facers are true vapor barriers, even if not air tight, but it's fine even with the attic ventilation (or lack thereof) as-is, or you would have visible moisture/mold issues on the roof.

    Air sealing the walls will make a difference too. Most capes have substantially more wall area than roof/ceiling area, and most of your heat loss is out of walls & windows, not the ceiling. But air leakage can be huge. The most critical air leaks are those at the bottom of the house (foundation sill & band joist, dryer vents with poorly sealed back draft stoppers, etc), and those at the top of house, since the vertical distance between them defines the magnitude of the stack effect pressures. Any plumbing stacks, flue chases or electrical runs that go from the basement to the attic are major offenders for driving air leaks.

    That retrofit can-light that's just jammed in there will be impossible to air seal as-is. Replacing it with a surface mount LED fixture with a standard electrical box will make that easier. A the very least mount the can light so that it can't move, and install a cardboard box (with sufficient size/ clearance to meet fire codes), over it, taping the seams with house wrap tape, and taping & caulking the box to the ceiling gypsum.

    Yes, use a chute like Raft-R-Mate (I prefer more rigid versions than foamies myself) to guarantee that the insulation can never contact the roof deck.
     
  16. Dana

    Dana In the trades

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    BTW: Even for a leaky barely-insulated cape, in US climate zone 4A a monthly heating bill of $650/month for the winter months is still quite a lot.

    How is the place being heated? (Electric baseboard?)

    How many square feet of conditioned space?

    In the pictures it looks like there are some lineset-hide conduits to multiple locations. Is that for split-AC air handlers, or is it ductless heating/cooling... or ???

    In your climate with that inherently back-ventilated aluminum siding the walls can be safely retrofitted with blown cellulose or fiberglass without increased risk of wintertime moisture accumulation in the sheathing. It may be easier to do that from the interior than trying to lift and re-install sections of siding drilling from the exterior. Even without addressing the myriad of wall penetrations directly, dense-packing fiberglass to 1.8lbs per cubic foot, or cellulose to 3 lbs per cubic foot would reduce air leakage through the walls by more than 90%. I'm not sure how much NYSERDA would kick in for those efforts (the programs change year on year, and I don't really keep up with NY), but even if it has to be done out of pocket the "payback" is pretty short years.
     
  17. lordoftheflies

    lordoftheflies Member

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    Well I'm up here and I'm removing the old insulation. It's shot and useless. I will spray foam the joints and plug all cavities.

    I can buy one of those rockwool covers for the hithats at the Depot. That's better than a cardboard box. Will foam seal those too. There's only one atm and 3 in the bathroom.

    I will install faced r13 or r15 whichever they have with the face near the conditioned space after dealing. Then I will lay r-38 unfsced on top of it. I researched attic fans and concluded it's a bad idea. I have a tiny bit of mold at the vent stack because the old seal leaked but I had that replaced about a few months ago so it should be good.

    Using some plywood as a mobile floor. Knee be pads, mask, and nitrile gloves. At least itnisnt 1000 thousand degrees today.

    20190701_133806.jpg 20190701_133812.jpg 20190701_130005.jpg 20190701_130209.jpg
     
  18. lordoftheflies

    lordoftheflies Member

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    I have minisplit ductless electric units. There is literally zero insulation in the walls. About 2100 sq ft plus an unconditioned basement.
     

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  19. Dana

    Dana In the trades

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    Not correct. You have a gable vented roof, which appears to be fine, since there doesn't seem to be any mold or rot issues in the attic. You never want to mix gable venting and soffit-to-ridge venting anyway. Let's not steal a defeat from the jaws of victory by trying to hack in some alternate venting scheme.
     
  20. lordoftheflies

    lordoftheflies Member

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    And remember I live just outside of NYC so con Edison screws us from the front and the back and any other way it can.
     
  21. lordoftheflies

    lordoftheflies Member

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    How do I deal with this? Insulation goes down to the crawl space. Should I cut some foam board and spray foam seal it? Stuff with insulation (guessing this is bad)? The wall below does not have an access panel so I'd have to do more demo to get back there.

    20190701_135816.jpg
     
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