I’ve been putting off insulating my house for a long time because I’m confused by the orientation of the paper facing .
as i understand it, hot air carries more moisture than cold air. therefore, regardless of your climate — (assuming you heat sometime during the year, and cool sometime during the year) — the paper facing is counterproductive half the time.
bottom line — I’m in florida, Never run the heat. Only A/C. Humidity in the summer is horendous. plus, I’m on the river. house is framed yellow pine, pine diagonal sheathing, OSB over that, then 30 # felt and western red cedar shingles. interior is wide open studs.
thanks for the help
Replies
The text book answer is to install the vapor barrier toward the outside of the house.
Really though, the kraft facing on insulation is a poor vapor barrier at best. How about installing un-faced R-15 fiberglass batt insulation with no vapor barrier? The 30# felt is a vapor barrier and although it does have about a million nail holes in it, felt is supposed to self seal around the nails.
BTW - is this house under construction or what? It sounds like you live there but there is no interior wall finishes - just bare studs?
Edited 11/12/2005 7:58 am ET by Matt
most southern homes I see have the kraft paper visible from the inside of the house room, during construction b4 sheetrock
Right - he is in the deep south. Stated he never uses the heat.
How about filling out your profile so we know what area you live in. You've been around long enough.
ok just lazy
yeah, the house is under construction -- I'm camped out fairly comfortably though. I finished my shop and office first. the office has a kitchen and bathroom, so I'm taking my own sweet time on the rest of the place. actually -- the land itself has been a pile of work. when I bought it the overgrowth was so dense that it took twenty minutes to hack your way to the river, now I have grass on the first acre and have kept many of the select trees, and you can get down to the fishin' hole easily.
You might want to look here.http://www.buildingscience.com/housesthatwork/hothumid/default.htm
Okay so I'm a bit confused.The building sciences link states that for a Cold climate ("Boston" house), they show rigid foam insulation on the OUTSIDE of the house (on top of the OSB sheathing). There is a little field note, but they don't publish the notes (at least on that page)However, they also have a link to their sheathings PDF which shows a cold climate house with NO rigid foam board.So which is it? Rigid foam on the outside or not?
If you look at the Chicago, Denver, Minniapolis, and Portland profiles there is a link (just under the title) to a PDF file which gives all of the details of construction and links to other reports.All of them, but the Denver show exterior foam insulation.It is not that can't or must have the foam, but it is one option.You might also want to look here and look at some of the case studies and demo projects.http://www.buildingscience.com/buildingamerica/default.htm
thanks bill,
I've looked at that site, I guess I'm going to have to follow more of their links -- since the houses they discuss don't resemble mine. but you see what I'm saying -- it's almost like every pundit out there wants to remain noncommittal.
I think the main issue with your question (vapor barrier placement) is that the last thing you want to do is trap moisture in the wall assembly. So, to answer that Q, you need to figure out where the bulk of the moisture is coming from for the majority of the time. Being in FLA that may seem like a "no brainer", but it is highly regional. To the other extreme, think of the Canadian Rockies where there is little rain, it's cool with low humidity, so the major moisture sources are from inside the home - cooking and bathing, and just plain people breathing...
You did well the way you formulated your Q "how do I insulate for this climate", but the most black and white would have to come from seasoned building professionals in your part of the state of FLA.
>> it's almost like every pundit out there wants to remain noncommittal << Maybe that's because in the end only you are responsible for what you build...
Here is a thought - why not get a insulation contractor out there to give you a bid - he can at least tell you what is customary for your area, and you may find that he can install it for nearly what $ you can buy it. That has been my experience.
thanks Matt and all.
Matt, funny you should mention the Canadian Rockies. the reason I never run the heat here in Florida is because I'm originally from Banff.
it's just getting to my time of year now. when I be chillin.
don't get me wrong. if I didn't love this country and state I wouldn't be here. the heat is just a little more than this corpulent carpenter can tolerate. fortunately, most of my work is interior (and therefore conditioned)
In reference to this guy's Q, I just looked at the Building Science Corp link for Orlando FLA. Their example building is a SIP structure. Hate to say it but to me this just shows that the BS guys can be a bit eccentric - knowing the way FLA people look at energy conservation I'd guess that that SIP case study house is - what - one of the 3 in the state :-)... At the very least, they need to do more case studies... They have good info but I've always said that I'm not necessarily buying what they are selling... I guess really though they are selling consulting - but not necessarily providing the free service of a great web site...
The people in FLA cool a way more than they heat, if at all, in some places. The cost of cooling (electricity) has been and still is way more than the cost of gas for heating. The SIPS wall but not at the R30 level would still be worth considering since it's quite airtight and you should not have to worry about hot moist exterior air getting to the back of the drywall or other interior finish to condense and cause mould.
It's hard to beat what the folks at BSC are doing and talking about in terms of durable, problem free, healthy, efficient housing. Joe Lstiburek is co-chair of the technical committee for the American Lung Association "Health House" program. ( http://www.healthhouse.org ). They are 1 of 5 or 6 major partners with DOE in the Build America program. Large homebuilding corporations have used their services. Met Joe in 1985 and haven't seen much he's been wrong on since.
No one else in the building science field is in such high demand to speak to engineers, architects, builders, home inspectors and investment property owners associations. Without him, building science may still be in the closet as it was here in Canada. He helped get it out here before he went to the US in the late 80's. There are building digests referring to air leakage and sealing vapour barriers from researchers here as far back as 1953 and 1960. but it was not referred to in codes (weakly at that) until 1990, a full 30-35 years later.
I agree - they also recommend sealing up the under house area- i do not know who is "right" but thats done maybe 1 in 1000 homes in the South (my opinion)
who is right? them or the "building community" I do not know
The "sealed crawlspace" approach is not only promoted by Building Science Corp (BSC) but by others including Canada Mortgage and Housing. It's been written up in "Energy Design Update" and other well respected journals.
If you are going to vent a crawlspace (It does work), make sure the vents are large enough (actually very large) to allow enough warm outdoor air in to warm the space enough to prevent condensation on wood framing. In some cases, the venting has caused problems of mould and wood rot as it was small, allowed warm, moist air into the space where it cooled (from the cool soils/partial concrete foundation) and condensed on the wood over the summer......we now have a problem.
The vent approach leaves things to chance by depending on the varying air relative humidities, the size of the vents, wind or no wind to cause needed air exchange. By not allowing warm/hot moist air into the space (good airsealing needed- cheap) or soil moisture to evaporate into the air (a good moisture barrier- cheap), the potential problem is avoided.
I am not arguing the points - just saying in my part of the coastal sSouth East US no one is sealing crawl spaces i.e. the building science people have not convinced the "builders"
I can see not sealing where it's warm and energy costs like heating are not much of an issue.