Proper Attic Insulation
I would like to know how to properly insulate our attic. We just bought a brick ranch style home which was built in 1960. The home has a long roofline. The existing insulation is obviously not even close to R39, probably about R12 or so. The existing insulation is the blown in type. Here are my questions:
1) Should some type of plastic wrap (ie house wrap) be used on the floor of the attic to prevent moisture from the home entering the attic?
2) What would be the best way to insulate the attic and reduce any moisture build up there? Please describe the proper steps to take. Should the old insulation be removed before installing new insulation?
3) There is a whole-house fan which may be the cause of some of the humidity leaking into the attic. Should we have this whole house fan removed? (It does seem to cool the house down in the evening after a hot summer day).
4) We are going to have a new roof put on, and are considering a ridge vent. Is this a good idea?
For everyones knowledge and information, I copied the following e-mail over to here to allow for further commentary. Rays original message is at the bottom of the post.
#'s 1 and 5 are referring to the same thing. A continuous vapor barrier reduces the amount of moisture content via humidity levels which permeate the attic enclosure. It needs to be completely sealed to provide this benefit, which is difficult to achieve if their are any protrusions in the way. By having the vapor barrier in place on the under side of the attic floor insulation, you theoretically can reduce the amount of total attic ventilation in half from 1 square foot per every 150 square feet of attic floor space to 1 square foot for every 300 square feet of attic floor space.
# 2; If the existing insulation is not wet or moldy, I can see no reason to not allow it to remain, providing that the vapor barrier is in place3 under the existing insulation. You must ensure that when adding additional insulation to the attic floor, that you do not clog or inhibit the air flow from the fresh air soffit intake vents or at least install insulation baffle chutes to provide for the proper amount of air flowage clearance necessary to promote an equal amount of air flowage from the intake vents to the exhaust vents.
#3; I love whole house fans. But, there must be enough exhaust ventilation provided for, to allow the newly introduced air into the attic to be expelled. Youe existing 3 mushroom style static air vents are only about 10 % of the proper amount of exhaust ventilation required for your home and for the shingle manufacturers warranty to be validated.
#4; A ridge vent which contains an internal filter and an external wind deflecting baffle, such as the "Shingle Vent II", manufactured by Air Vent Corporation will provide the correct amount of attic exhaust ventilation, if run 100 % continuously from one end of the gable to the other. I install this exact brand of ridge vent on almost every single home we do around the Dundee, Elgin and Algonquin areas. 80 feet of this ridge vent at 18 square inches per lineal foot will provide about 1,440 square inches of exhaust NFVA. Now, you must equal that amount of exhaust with an equal or slightly greater amount of fresh air intake ventilation, which is usually located in the soffits, but can also be achieved by installing the Smart Vent , manufactured by DCI Products, Inc., under the first course of shingles on the roof.
#6; I personally have a high regard for the Tamko Heritage Architectural line of shingles. There are a great diversity of color choices and it comes with the AR, (Algae Resistant), granule feature, and has weathered the test of time for usage for over 15 years with no adverse affects from our previous installations. Prior to that, I used various other brands, which have since gone out of business or merged with other shingle manufacturers.
Ed - We just bought a brick 1960 ranch style home in the Xxxxxxxx area oo Xxxxxxx. The house has about 80 feet of roofline (includes the attached 2 car garage-unheated). The existing insulation is probably about R12 or so and is the blown in type. Here are my questions:
Adding insulation on top of insulation will only increase the R value.....12 inches is a great balance. Venting the attic as Ed describes will suffice.
Here is some further discussion for everyones interest on this subject.
Ed - thanks for getting back to me. Here are my follow up questions:
1) If our 1960 brick ranch has no vapor barrier in place on the under side of the attic floor insulation, it sounds from your answer to # 1 and # 2 that you definitely recommend installing the vapor barrier. I am not sure how 6" of existing loose insulation should be removed to install the vapor barrier. Don't the joists and electrical conduit pipes that are in the way act as obstructions when installing a vapor barrier? How would you know that the installation of the vapor barrier was done correctly and provided a complete seal?
Precisely Why I stated that it was difficult to achieve. I personally would prefer to over-ventilate than go through the procedure of installing a vapor barrier, which will wind up being penetrated and defeat the purpose anyway. Also, that would entail the removal, of perfectly good still functional insulation to properly install the vapor barrier on the floor of the attic.
2) Do you see whole house fans much anymore in your work as a roofer? I don't think they use them anymore in new construction, do they? Weren't they just a fad of the 1960's? The only thing separating the whole house fan from the attic space are the thin metal slats which close when not in use. These do not seem to provide an adequate seal for moisture, or for warm air escaping in the winter. Do you agree? By the way, the whole house fan is located in the hall way outside the bathroom. If we do keep it, shouldn't we insulate the opening from the inside during the winter, and perhaps even build a box made of insulation to put over it inside the attic? And yes I agree, our attic ventillation is seriously deficient.
I love how a whole house fan works. I imagine you could tape a plastic visqueen barrier around the hinged fins to eliminate heat loss into the attic in the winter time, but I believe this savings would be minimal, but now-a-days anything is better than paying the sky-rocketing energy increases.
I typically do not see the whole house fans, because they are usually mounted on an interior ceiling, which I usually do not get the opportunity to notice.
3) The Tamko architectural shingles carry a 30 year warranty correct? (Assuming the attic is properly vented of course). How is the GAF brand? Do any of these brands carry a color like a blue-grey?
Tamko has an "Oxford Grey" and a "Rustic Virginia Slate" and an oxford grey blended with charcoal black called "Thunderstorm Grey", which all go well with blue and when applied with a blue colored house, more blue hues are enhanced for a visual affect. Also, a lighter color from Tamko which picks up blue hues quite well is "Olde English Pewter".
I rarely use any GAF product, even though I can buy them slightly cheaper than Tamko or Certainteed, I have had good experience with the 2 other brands and do not jump ship with my loyalties just to gain additional profit.
4) My wife, the artist asked if you work with, or are familiar with unconventional roofing materials such as metal roofs or other materials such as Decra. Are these other type roofs significantly more money? Will they last longer?
I also have installed metal roofs, but primarily standing seam or batten seam and also clay, concrete and slate tile roofs, but the demand is not high enough around my area to pursue the premium priced alternatives usually.
One problem with using a product that has a small core of "Certified Contractors", is that the competition to install that product is only between a few select companies who tend to be able to leverage their selling price levels at a higher than typical level due to the lack of competitive bidding.
They are good products, but I typically encourage the use of such high end materials on the most intricate and difficult and steep roofing projects to avoid ever having to do it again 30-50 years down the roade.
Concrete tile that looks like slate is one of my favorites as an alternative, and is easier than most metal roofs on the home owners budget. ie; Somewheres between $ 4.00 to $ 6.00 per square foot for conrete roof tile.
p.s. I could show you a picture of our home on cookcountyassessor.com if you like.
Your address or PIN # would be necessary to view the Cook County assessors photo of your home.
don`t put housewrap ,It traps the moisture,and causes major problems,had a similar situation w/a customer who used plastic as a vapor barrier but pics are too big to post,all entries into attics by pipes should be insulated tightly,also w/high hat lighting ,be sure to buy the heat insulated version so you can insulate right up to them,w/non insulated type you have a high risk of fire--if your attic is not sealed well,the insulation will not have great effect,be sure to put raftermate to the soffit overhang for proper breathing,and definitely use a ridge vent:thumbsup:
Here's how to best remedy this situation...
Remove the existing blown in insulation.
Have minimum of 4 inches of 2# closed cell polyurethane foam installed ((Aged R value 6.5 per inch) as a vapor barrier.insulator.
This is a monolithic blanket over the ceiling, and since it is a closed cell foam, it is a true vapor parrier. This will be more costly than the alternatives, but will pay for itself in short order, and solve attic-to-celing hummidity problems.
Then still vent the attic/roof.
Hope this helps.
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