1920 1˝-story House, No Insulation, New Roof... - Insulation - DIY Chatroom Home Improvement Forum
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Old 12-18-2013, 07:20 PM   #1
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1920 1˝-story house, no insulation, new roof...


... And I'm wondering what to do upstairs. There's no insulation anywhere in the house, but it's well-built and tight, and we stay pretty toasty in the winter. The upstairs used to be unfinished, and sometime back in the 30s or 40s they put up some kind of particle-board-ish stuff for the walls. Fast-forward seventy years; the roof was getting to the end of its useful life and we had a new metal one installed. Right now, our upstairs has no ceiling, just knee-walls and a great view of the skip sheathing under our roof. There are small vents along the eaves, either original to the house or added very early on. The vented space includes not only the area outside the knee-walls but also the space between the first-floor ceiling and second-floor flooring. The upstairs is dry, stayed warm before we destroyed it, and has great ventilation in summer (the thing's a wind-tunnel, with a window at each end, one of which faces the prevailing winds).
Now, when they put on the new roof, they first removed THREE layers of comp shingles, plus the old cedar shakes underneath. I'm guessing that the R-value of that overbuilt monster was a little higher than my current metal roof, so I'm thinking I should insulate. But I'm not sure what to use. My biggest fear is blocking airflow and getting moisture trapped in my walls or between ceiling and floor, so I don't want to insulate those second-floor floor joists if I don't have to. If I just insulate the ceiling and knee-walls, though, how effective will that be, since the under-floor airspace basically connects to the outside? The rafters are just 2x4 so I don't have a tremendous amount of room to play with.
Anyway, this sort of remodeling is totally new to me, so if I'm leaving anything out, let me know! I appreciate any advice, especially if it's good.
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Old 12-19-2013, 06:29 AM   #2
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At some point how do you plan on finishing this out?
Is it going to be living space, attic?
Posting a picture or two is always nice and helps clear things up.
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Old 12-19-2013, 06:39 AM   #3
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How is it framed?

To insulate the bottom of a roof,you need an air space and then insulation---and a vent for the air space----post a picture--let us know where you live---climate must be considered---
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Old 12-19-2013, 09:27 PM   #4
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Another close neighbor of mine.... welcome!

The floor space under/between the knee walls should not be insulated if the room above is heated. There should be foam board stopping outside air from the vents to that floor area; http://oikos.com/esb/51/sideattics.html

The rafters should be furred down with a baffled air space continuous to ridge--- to get code minimum R-value in the sloped ceiling; R-38; footnote "j" pp. 30; http://www.energy.wsu.edu/Documents/...s%20Energy.pdf

Gary
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Old 12-20-2013, 01:02 AM   #5
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https://picasaweb.google.com/1057372...CJbWqbC_0ubmLw

That link should let you see pictures of the upstairs, among other things. The room was finished when we moved in, with vented attic space behind the knee walls, so we're not exactly converting attic to living space, but rather replacing all the ceiling.

Oh'mike: To be clear, do you mean that we need ceiling--air-space--insulation--roof? Or ceiling--air-space--insulation--air-space--roof? We live in Vancouver, WA, which I believe puts us in Zone 4 of the IECC map.

Gary in WA: Oh, duh... I'd seen something like this before referring to 1-1/2 story houses, but just spaced it entirely. My only question is, "Would there be a good reason to keep air flow under that floor?" I know it might sound stupid, but I'm wondering if there was some reason they didn't seal off that air-space between floor and ceiling.
Also, I'm not super-worried about bringing this up to code. The whole house is uninsulated, and it's not feasible (or really necessary) to insulate the whole thing. I'm just wondering what I could use--without furring out rafters, if possible--to give a bit of a thermal barrier up there.

If I seal the air-space between downstairs ceiling and upstairs floor, and insulate along the knee walls and the new ceiling upstairs, do I need a vapor barrier? They didn't have one before, and condensation/infiltration didn't seem to be a problem, but with the metal roof and new insulation and changed air-flow, will that change things? Again, this is pretty new territory for me. My house has been around for almost a hundred years, and I'd really hate to do something bone-headed and wreck it.

Thanks again!
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Old 12-20-2013, 01:08 AM   #6
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Oops, missed one thing: oh'mike, it's... um... not balloon-framed. I'm up too late and can't for the life of me recall what the right term is; the second story is framed on top of the first story. If you look down along the gable-end walls, you see the top plate of the first story wall.
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Old 12-20-2013, 01:32 PM   #7
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I gave you our State Energy Code requirements (trumps all) that are in force, not the IECC map.... R-38 is required for sloped ceilings in your location. Air flow under the floor effectively costs you more money to heat the room below. If fb is $$$ use some fiberglass insulation in a plastic bag to air seal it. We need a vapor retarder- asphalt paper-faced batts or Membrain; a sheet variable retarder on the drywall backside.
Is metal roofing ventilated at soffit/ridge?

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Old 12-20-2013, 06:25 PM   #8
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Yeah, the roofing is vented along the eaves and has a ridge vent. (As a random aside, when they laid the comp roofing over the cedar shakes, one of the layers had an old metal ridge vent instead of cut-outs; the next couple layers were just installed *over* the ridge.)
Two questions: If I'm just doing this one room, and there's no permit, do I *have* to follow the state requirements? Or as a homeowner do I get a free pass?
Second: Just to be totally clear, aside from tarpaper on the exterior wall sheathing, there is no vapor barrier nor insulation anywhere in the house. Everything looks pretty dry, and the attics got cold but nothing stored in them was damaged by frost or condensation last year. If I put up a vapor barrier and change that air-flow, I'm not gonna cause any condensation problems, am I?
Since the side attics are over living space, I'm thinking that my best bet would be to make the planks I've laid in part of them into a more-permanent floor, isolating the first-floor ceiling from the attic space. If I do that, I should insulate the new floor in the side attics (since it's over living space), but I don't need to worry about the space between floor and ceiling any more, since that's between two conditioned areas, right?
Old house=steep learning curve. Good thing most of this stuff is fun for us! :P
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Old 12-20-2013, 07:17 PM   #9
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Yes, insulate the floor in the knee wall attics and not the rafters. No condensation now as you are heating the attic because you have no thermal barrier separating the two spaces. Any attic ventilation is moving the heated air from below with it. The gable/window walls should be insulated and the knee walls- if heating that room between knee walls. Getting a permit is entirely up to you; keep in mind if finishing you will probably add electrical and that Inspector will note it to Building Department...AND your HO Insurance carrier is more likely to honor a future claim if permitted when the house burns down (and at selling time for work done).

" but I don't need to worry about the space between floor and ceiling any more, since that's between two conditioned areas, right?"---------- correct, no insulation between conditioned areas other than for sound prevention.

Vapor retarders are to stop/slow moisture from cooking, bathing, occupants, pets that add moisture to the indoor air; http://energy.gov/energysaver/articl...sion-retarders

Link at the bottom of that article on air-seal (imperative) your attic first.

Gary
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Old 12-21-2013, 12:16 AM   #10
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Thanks again, Gary! All the electrical, etc. is already installed--again, this *was* a finished room; we simply demolished the ceiling and pseudo-masonite walls to install a new one.
If I seal the side attics out of our conditioned-space envelope, am I gonna start seeing condensation or problems using that area for storage? Should I put waterproof or -resistant flooring in those attic spaces? When we insulate the knee-walls, should I throw up some boards on the attic side of the insulation, or just leave the vapor barrier exposed?
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Old 12-21-2013, 07:14 PM   #11
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"If I seal the side attics out of our conditioned-space envelope, am I gonna start seeing condensation or problems using that area for storage?"----------- no, not if you have ventilation.

" Should I put waterproof or -resistant flooring in those attic spaces?"---------- no. Let the moisture through. Leave the flooring off to get the required R-value over the ceiling below. Sell/store the attic stuff elsewhere.

"When we insulate the knee-walls, should I throw up some boards on the attic side of the insulation, or just leave the vapor barrier exposed?"--- IMO, add some Tyvek housewrap to the backside of the insulation to prevent wind-washing of the batts, check with local AHJ.

Gary
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Old 12-26-2013, 12:18 AM   #12
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So, I'm thinking the easiest thing to do is to just extend the ceiling and insulation down through the side attics, and let those vents just go above it up to the ridge vent. Mmmmm.... warm upstairs... Guess we'll start this weekend.
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