Insulating old houses

17 years ago

I hope this is the right forum to post to for this problem. If not, please tell me the appropriate one. That said, here's my problem. My daughter bought a 100+ year old Victorian-era duplex. Among its many, many problems is the insulation. It has a large unheated, uninsulated attic which could be converted to living space. She was advised to put insulation between the second story and the attic, and insulate the attic when she's ready to finish it off. I say that's absurd, and to go ahead and insulate the attic now instead of wasting money doing the second floor (which I believe may involve ripping out ceilings). What do the experts say? She's really desperate for advice that doesn't come with a price tag. Thanks in advance.

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Comments (4)

housekeeping
17 years ago
I think insulating the attic between the second story and the attic is done by lifting the attic floor (if any) and installing the insulation between the attic floor joists and on top of the second story ceiling. It is usually described as the best first step towards energy conservation. I don't think it needs to involve the second story ceiling, at all (other than being careful not to bash up the plaster keys from the top side.)

You may be worried about the need for a vapor barrier between living space and insulation. I wish there was a definitive answer on this one, but in fact there are two schools of thought. I happen to believe that all things considered, it's better to insulate between the second story and attic space, no matter what, even without a vapor barrier. You can paint the ceiling with vapor retardant paint, which does help. The other school of thought is that you need a VB. I agree about VB in walls, but am not so worried about attics. I know there is a risk you could have condensation within the insulation, but unlike walls it's not a really inaccessible space. You could monitor it, if you found it was a big problem. Another way to handle this is with agressive use of vent fans, and particularly meticulous attention to sealing up infiltration lower down on the building.

The good news is that while insulation is not free, it's not that bad either, and this year I think there is a tax credit. And it's something that ordinary people can do themselves. There hardest part is pulling up the attic floor if it's nailed down.

If your daughter eventually decides to make part of the attic into living space the insulation won't need to be torn out, either.

YOu might want to check another thread by Abbey1930, where I blathered on about my theory of insulation.

HTH,

Molly~
jamesbodell
17 years ago
If the attic has wall board (or plaster and lathe) up and just planks for a floor (which sounds odd) then just put it in the floor. leave it there when/if you finish the attic later. If you know you are going to finish the attic, and you need to spend money to either lift full subfloor (and or finished floor) or walls, then remove the walls, insulate, and wait to put back the walls when ready to complete the space. Just be sure you put in a space for air to pass between the roof deck and the insualtion, and install ridge and sophet vents.
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Are you sure there is no wall insulation? I can't imagine a recently redone lathe and plaster wall without insulation (and the necessary warm-side vapor barrier). Usually the dilemma is a house like mine with no wall insulation and original plaster and therefore no way to insulate without damage to the historic materials. Don't get confused between the vapor barriers installed in the wall assemblies just underneath the interior wall finish, i.e. on the warm side of the insulation and the moisture and air infiltration barriers installed under the sheathing or other exterior cladding. The former is to block tramission of interior moisture into the insulation material where in cold climates it can condense and get trapped causing mold problems. The two later products are intended block exterior moisture, primarily rain, from being driven from the outside into the wall assembly. The standard order of march in weatherizing an old house: insulate the attic cavities, first; then do a heroic job with the caulk gun to eliminate small air leaks, inside and out and install or replace weatherstripping around openings of doors and windows; then look at wall insulation. Note that under floor insulation is not high on this list even though it is an intuitive thing. Floor insulation projects are usually aimed at stopping air infiltration but most insulation materials aren't designed to combat infiltration, per se. However, tightening up other, higher, parts of the house will prevent them from drawing cold air up through the floor in the first place. This overall plan of attack is based on first doing the things with the most efficient payback in energy savings for the dollars invested. And sexy, or not, attic insulation and caulking are the top two. For under your structure, you may need a vapor barrier laid on the dirt to stop moisture vapor from rising from the soil into your living space and the framing of the structure, and possibly ventilation of the crawl space (this is the controversial part and I think depends,greatly, on local conditions especially your outdoor drainage situation.) BTW, I would carefully assess the choice between wood siding and Hardie-plank type products. They are not equivalent in how they look and I think the HP makes an old building look odd. Unless you siding is totally rotted, you can probably rehab most of it, then buy only a small amount to finish the job. There is a series of National Park Service publications regarding the care of old buildings. One title is devoted to weatherizing old structures. I've attached a link below, scroll down the list of titles until you find the ones that interest you. HTH, Molly~ Here is a link that might be useful: National Park Service Preservation Brief Series - Wide range of old house topics
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Even better than formaldehyde-free Johns Manville Comfort-Therm encapsulated fiberglass batts is Owens-Corning Miraflex encapsulated long fiber spun fiberglass. The Miraflex looks and almost feels like dacron polyester insulation. The long fibers have a twist to them, and theis enables them to be used without binder. It also means that they don't shed fiberglass shards like tradtional products. They will shed a little, but it's far less. Consequently the itching and respiratory issues are much less. The downside is that Miraflex runs about twice the cost of competing products. But it's what I chose to insulate the floor of my attic and under the main home floor in the vented crawlspace. I like the fact that if I have to go in and do electrical or plumbing work, that the insulation will be much less nasty to move around and reposition. I am wondering why you want to put insulation directly under the roof, but perhaps that's an issue for a different thread.
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wangshan, I have seen 50 year old rock wool, and 75 year old dangerous mineral stuff on pipes; unfortunately I still have some intact hay insulation (from about 3' above the ground to the ceiling). Will "blown in insulation" fill the gaps? My best guess about the survival of the old stuff is that the house is on high ground (reduced moisture + 'luck'). I'm not a newcomer to old houses, but this is the first time I've found hay as insulation. My granddad had a house (ca. 1700) with no insulation (he added vermiculite in the 1950'S); my folks had a dutch colonial (ca. 1914) and added some fiberglass/vermiculite/beadboard); I've lived/worked in other houses from the 1800's, never found intact hay (decomposed yes). Parts of my house are new 1980's,1950's,1930's; others are older 1750's (original section - where the hay is (it was a milk house for Quaker dairy farmers). I don't want to gut the walls (heck I like the 84" ceilings)(they give me an excuse to build furniture to fit!). And they still look good! Dad
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this is what i read about balloon framing and insulation: Because of where you live in the cold Northeast - I'm just above you in NH - it would be a GRAVE mistake to add insulation in the wall cavity. The reason your house is still standing with no wood rot is simple. The balloon framing used in houses of that period - I lived in one back in Cincinnati, OH in the 1970's and 80's - allows water vapor that passes through the plaster and lath to be vented up into the attic of your home. Once up there, it usually was able to dissipate out gable vents or through the roofing. Many older homes had roofing material and roof sheathing that would allow lots of air to pass through them, but not rain water back into the attic. Balloon construction was probably invented to do this job as houses built without this open passageway probably developed rot in short time as the water vapor in the winter time would condense in the cavity and be unable to EVAPORATE quickly. Read this column I just posted about Vapor Barriers vs House Wraps to give you more background. If there was a way for you to install a vapor barrier to STOP the water vapor from getting into the wall cavity, then I'd say move ahead with the insulation. But I don't know of any TRUE paint-on or spray on vapor barrier that would provide enough of a seal. Im very certain I have balloon framing
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sharon_sd
17 years ago
If it were my house and I planned to do convert the attic to living space at some time, if I didn't need to use the attic as storage, I would just lay batt insulation on top of the floor. Then it could be lifted to go in the ceiling and walls when I was ready to renovate. That way the attic doesn't have to be a part of the heated area of the house until it is actually a living space.
senorjosef
17 years ago
From what I've read, insulating the roof of the attic and leaving the space unfinished may cause moisture problems. If the space is unfinished you want the attic cool and the insulation between it and the heated second floor. Make sure to put the kraft faced paper down, toward the warm side. Strip the kraft paper off 2 feet around fireplace (if there is one). When you are ready to finish the space off, presumably a few years down the road, don't remove the floor insulation when you lay down flooring. It will make a nice sound barrier.

Insulating old houses

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housekeeping

jamesbodell

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