I did a search online and also searched on the forum, but wanted to ask here as well. From my searchs, it appears that using faced insulation with the vapor barrier facing the inside would be appropriate.
While knowing full well many here do not care for fiberglass insulation. . .we will be installing it in the basement of a house we’re working on. Basement is slab on grade, walks right out into the backyard. House is located in San Francisco Bay Area, about a couple of miles from the beach, so we get our share of fog. 1940’s era, 2×6 construction, the exterior is wood siding, with some sort of paper between the siding and the framing. The side walls are less then a couple of inches from the neighbors exterior side walls, if that makes a difference.
The basement is large enough to turn into a nice family or great room eventually. The laundry, water heater and furnace are located in this basement. We plan on drywalling immediatly after we insulate.
So the question, should I use faced or unfaced? Thanks in advance.
Tark
Replies
>>exterior is wood siding, with some sort of paper between the siding and the framing
My question would be, what is that paper and are those walls staying completely dry? If they are getting at all wet, and drying out because they are now open, insulating them may trap moisture that has never been trapped before. Many an old building has been ruined by being insulated.
To answer your question, faced would be most appropriate, with the facing in. Are you also sheetrocking?
Edited 6/3/2007 11:54 pm by davidmeiland
The walls were previously sheetrocked and have been dry. The paper in question is kind thin, nothing like 15lb tar paper. Its over lapping it self, so it appears it is meant to keep any moisture that gets through the siding to stay away from the interior. We had new plumbing and electrical brought in and it was easier to take down all the old sheetrock and put new after all the mechanics were put in.Tark
Personally I like the encapsulated insulation (like J-M ComfortTherm)
http://www.jm.com/insulation/building_insulation/products/bid0007_comforttherm.pdf
Jeff
Edited 6/4/2007 12:29 am ET by Jeff_Clarke
Tark,
What you have is not a "slab on grade", that phrase , by definition means no basement, so if I interpret correctly , what you really have is three sides of a beasement below grade,or into the side of a hill, typically, with the 4th a walkout to grade, thusly these are called "walkout basements".
In regards to the paper you refer to, is there sheathing on this house? I assume the paper is between the siding and the sheathing (maybe 1x6 boards), if it's a reddish pink color it's probably rosin paper, if it's black it's probaly builders felt (15# felt).
As to insulation in a basement , no vapor barrier, use unfaced fiberglass, or better yet use blue poly foam instead, no worries about moisture/condensation with it, apply the blue foam directly to the foundation, install strapping on top or build your walls just in front of the foam boards, with no insulation in the wall cavity.
Geoff
Perhaps I might be using the phrase basement too loosely then. The room in question is level with the garage at the front of the house and is level with the backyard. The backyard is flat too. The room has 8' ceilings. I guess the reason I've always called it the basement was that it has a floor drain off to one side of the room and has a very gently slope towards it. Yet there is no way water could ever enter the room unless the water heater let loose or the laundry backed up. Water never enters from the backyard. Seems like with your suggestion to use unfaced and an earlier person suggesting to use faced, I'm still left with a problem of figuring out which one to use.BTW: No sheathing of any kind. Just the paper, black on one side/tan on the other, not much thicker then a couple of sheets of newspaper in my opinion and then the wood siding.Could you give me a bit more info on why I should use unfaced in this particular application?
Edited 6/4/2007 3:45 am by Tark
Tark,
I think you have left a lot of readers confused. Are these walls concrete walls or wood-framed walls? The type of insulation will depend on the type of walls you want to insulate.
Could you give me a bit more info on why I should use unfaced in this particular application?
Simple answer--it's easier (sometimes) to apply a vapor barrier by itself rather than as something stuck on batt insulation.
Why is that simpler? Because, then, you never have the question of "You put the insulation in backwards" (since at least one person will tell you that, either way you install it).
If you'd like to submerge yourself in these arguments a bit, please consult the buildingscience site, they have all sorts of info on controling how moisture enters and leaves our buildings.
And for my 2¢ worth, with open stud bays, cellulose (or denim out there in CA) would be my first choice. That has to do with how "full" you can make the bays, eliminating voids, gaps, and the like.Occupational hazard of my occupation not being around (sorry Bubba)
My vote is with Piffen, for the same reason. Since it is becoming a conditioned/occupied space, letting it dry to the inside is the safest approch. Placing a vp inside, even as poor as the kraft faced insulation is, stands about a 50/50 chance of being wrong.
Dave
Just so's we're clear, I am imagining this as mostly above grade, wood-framed space. Minimal lot slope, not a hole in the ground... typical of Bay Area garages and "basements". There is probably concrete to a few feet above the floor. Lots of folks turn this into conditioned space, and it's pretty much like the rest of the house except the concrete floor. The interior will be fairly damp because it probably does not have a barrier under the slab. He should certainly ask his inspector what will be acceptable.
Everyone,Davidmeiland's description is the most accutate. Wood framing (I think I mentioned 2X6 construction earlier) and the foundation only extends about 14" above the concrete floor. Since the concrete floor is original construction, I do not believe that there is anything in it that would stop moisture from coming up. The room is about 16' by 24'. Since the laundry, furnace and water heater are all in this room, I was worried about the amount of moisture being produced inside the structure, hence I was leaning to faced. The room has newer Milgard vinly windows and pre-hung exterior door that seals up tight which will lead out to the backyard, so the room is not drafty.
The room will be conditioned, and eventually will become either a family room.Although I do not post often, I lurk several times a week and read the opinions of many of folks here and have come to respect many of them, including Davidmeiland's, Piffin's, and others. Thanks for all the input, even though there is not a consensus yet. I may give the building department a call. If the additional information above assists in refining anyone's thoughts, I would certainly like to hear back.
Edited 6/4/2007 11:41 am by Tark
That would make me just as likely to want unfaced.The lower crete could wick ground water up into the wall, and the moderate climate means moisture could enter the assembly from either direction so it should be allowed to migrate to dry either way and avoid being trapped.But you are right - the inspector is always right, no mater how wrong he is...;)
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True... older house (assumption), likely no sill sealer under the mudsill, probability of clay soil is fairly high, moisture from the concrete is a definite possibility. I guess from my reading on these issues, the highest likelihood of moisture in the wall is from inside, people breathing, boiling spaghetti, taking showers, etc.
Reality in the Bay Area is that there is so much drying during the year that you can get away with murder. Here on my island, or on yours, you'd get spanked.
Good read David.
I have seen a few short stem walls with framed construction sitting on them, but they are usually attached garages. I have even converted a few of them to bonus rooms. Most were already semi finished inside,dw ceilings and walls, so it was just a matter of removing the overhead door and adding a raised floor over the slab. I don't think I have ever encounter a vp in any of them, since they were unconditioned spaces originally. Even after adding HVAC to them, I would use unfaced batts for the floor and door fill in wall because it is a SWAG in this area as to which way and when humid air will move in/out of one of those conversions.
When in doubt I tend to lean toward no vp. We have a couple hundred years of house built without them. Not necessarily energy efficient, mind you, but they haven't rotted out from the inside or become uninhabitable from mold issues.
Dave
For a basement use unfaced
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How many months in a year will the air conditioning be running in that room?
How many months in a year will the heat be running in that room?
For info - be very careful with faced. I had some faced insulation left over and didn't want to travel to get faced. Installed faced, then cut a slit in the facing of each batt and installed plastic sheeting on the outside. When I came to sheet rock that area, the plastic was practically dripping water. Took all down and put in unfaced. Left for a few days - no condensation - no nothing. This was in spring time in New hampshire but really illustrates the need to make sure one does not have two barriers.
Don't mess with the status quo, bro.
When in doubt, air it out.
(Sorry, the only basement I'm familiar with is the one on "That 70's Show".)
No vapor barrier.