Insulating outside wall – confused

I’m down to studs on the outside wall of my kitchen during the remodel. Before I put up drywall I was thinking I’d add insulation, partly for noise protection and for any hvac benefits. I’ve done some searching on the forum and now I’m just confused. What type of insulation and whether or not to have a vapor barrier? Nothing in my house is insulated except the ceiling, so maybe I shouldn’t even bother?
Thanks for your comments.
Replies
Unless you're in Nirvana or Utopia, there's probably benefit to be had from insulation, and there's no better time to do it. What's your climate like? If you heat your house, the best place for the vapor barrier is most likely on the inside (warm side) to keep warm, moist air from leakng through in winter and condensing on the cold outer surfaces. If you live in a hot humid place with a lot of AC going on, it might be better to put the barrier on the outside, but let someone from the South help you with that.
Al Mollitor, Sharon, MA
Well, that's exactly why I'm confused. I live in Kansas City, and we have the worst of both. It's extremely hot and humid in the summer and can be bitter cold in the winter.
Thought it was only here in Southern Cal that no insulatioon was standard. What are your energy bills like?
Joe H
Most of the old homes in my area were built this way, near as I can tell. Knob and tube in the walls and no insulation anywhere else either. No K&T in this wall though.
Bills aren't bad actually. I put both the gas and electric on even pay and they're about $50 per month each. The house is around 1500 sq ft. We use a programmable thermostat.
Edited 5/16/2003 9:17:53 AM ET by CAMPBELLDUST
I call Kansas City an EMC - equally misserable climate. As Mike Murphy says we have one good day in the spring and one in the fall.
Look at http://www.buildingscience.com under houses that work, KC is in a heating climate.
A vapor RETARDER is required. But because there is also signficant cooling plastic is not recommended. If you have an moist air get in from the outside during the summer it would condense on the plastic and run down the inside of the walls.
The most important thing that you can do is to limit any air movement.
Thanks Bill. What do you consider a vapor retarder versus a vapor barrier? Is fiberglass paper faced on one side what I should use?
Money isn't really on object here, but time is. I'd like to find a product that I can readily obtain and install myself. I have about a week and a half before kitchen cabinets are installed.
because fiberglass does not help to prevent air flow, any air leak in your wall system will allow air to flow freely thru, leading to the possibility of moisture issues.
The problems with vapor barriers are that they are inherently un-forgiving. As others pointed out, warm moist outside air is a concern in AC season, and warm moist inside air (especially in kitchens and bathrooms) is a concern in heating season, each coming from the opposite side of your wall. Do it wrong, and if you have an air leak, and you'll have moisture trouble.
The reason why some are recommending spray foam or cellulouse (dense pack) is that these two types of insulation greatly reduce air flow. Although not all codes are up-to-date on this matter, the theory is that little enough air flow = little risk of moiture being condensed out of that air stream that could lead to moisture problems.
Cellulouse is something that you can DIY: install the drywall, leaving a gap at the top of the wall for the hose to go into. Rent the blower where you buy the cells and practice your density a bit before you 'let her rip' (too much will blow out the drywall, too little will settle and leave a gap at the top). The best way to practice is with a 'prototype' stud bay (make this in the driveway) and try it once or twice (fill it, then remove the drywall piece and check your work). The pros can tell just from the sound the machine is making when they've got it right. You insert the hose all the way to the bottom of the stud bay, making sure to get it past all wiring or plumbing to the bottom. You start blowing in the cells and slowly pull the hose out, making sure that the wall cavity is filled completly and leaves no gaps or un-dense portions, but also making sure that you don't blow out the drywall (bulges are ugly).
Foam is more difficult because you have to hire the crew with the special machine. There are two types of foams, closed cell and open cell.
The closed cell people spray just an inch or two, then fill the rest with fiberglass. My concern about closed cell is that it does not breathe at all.
The open cell people (Icynene) fill the whole bay solid (no additional FG is needed), and this material breathes, kind of like dense pack cells, allowing some air transfer to occur, over a 24 hour period, which helps keep a healthy house/living environment.
A too tightly sealed house requires additional air handling equipment to keep the air fresh inside. Since you've got an old house I doubt you've any risk of this no matter what type of insulation you use.
Other advantages of foam or cells over fiberglass are: more dense walls = quieter home, more dense insulation materials = more resistance to infra red heat (fg allows IR to pass right thru, just like air), which can help cooling bills when the sun's rays are heating the outer skin enough to radiate IR thru the stud bay cavity.
I wish this information was contained in some Frequently Asked Questions on this site because this comes up ALL THE TIME (it was my turn to answer). Someone else will chime in if I missed anything!
:o)
Norm
Edited 5/16/2003 12:51:31 PM ET by Norm
Any kind of insulation will help. and depends on the space you have as to what you can use. Foam is the highest "value" for its thickness but not the lowest in price. Give us some more details. The reason for the plastic sheet on the inside is to stop condensation rotting the wood in the walls and preventing fungus forming.
Not only prevents fungus and rot but in the winter when that warm moist air trys to migrate out and condenses, it freezes within the insulation and negates any insulative value it has.
Call your building dept, they will be able to tell you where it should be placed.
Don't want to confuse the issue here ( where to place moisture barrier), but if wnter-time moisture gets inside wall cavities and cuts down the R value on insulated walls that have no moisture barrier...then please explain why blown-in cellulose insulation is still popular; especially among retrofit jobs involving very old homes that had never been insulated. Does the fact that the blown-in stuff compacts so tightly, that it keeps moisture from penetrating...or do you believe that moisture does affect blown-in material?
Just curious about what y'all think. I just installed blown-in insulation in approx 2200 sq. ft of stud cavity walls in an older home. Of course there is no vapor barrier installed in this procedure. I don't insulate this way very often. Last time was in 1997. Owner claims this type of insul really made a difference. Still happy with results today. My region has pretty harsh winters ( Ohio Valley Region/ Pittsburgh, PA).
Anybody care to comment?
Thanks.
Davo
Most moisture, by far, moves with air movements. If you stop movement, such as by densepacking, the amount of moisture in the walls in a typical home is low.
Added to that is that the interior finish (plaster or drywall with paint ) is also a vapor retarder.
Here are a couple pics of the wall I'm talking about. The spaces are slightly irregular, plus I'll be adding studs to flatten the wall a little.
Taking into account the short time you have and shallow bays to insulate. I would cut solid foam sheets to the width of each bay minus 3/4 inch. Install in each bay and foam in a can the gaps at each side. Use the thickest foam that will fit, Cut around any electrical boxes etc but make sure to foam behind them. Looking at your pictures should take a day or less to do.
I looked at the foam sheets over the weekend and they don't make them 3 1/2" thick. Are you supposed to use multiple sheets to achieve the thickness of your wall? It seems like that would be a lot of custom cutting. I ended up buying R13 3 1/2" by 15" batts, paper faced, but I haven't installed them yet. Any other comments?
That will work, however, I would "foam in a can" around electric boxs and other stuff in the way of the fiber glass.