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.
Ed
Ray,
#'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
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:
1) Should some type of plastic wrap (ie house wrap) be used on the floor of the attic to prevent moisture/humidity from the house 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? Is cotton insulation effective as an insulator?
3) The home has 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). I should also mention there are only 3 very small passive vents on the roof.
4) We are going to have a new roof put on after we take some bids, and are considering a ridge vent. Is this a good idea?
5) I am guessing we have no vapor retarder under the blown in insulation since the home was built in 1960. The Owens-Corning site recommends one square foot of free vent area for every 150 sq ft of attic floor. Do you agree.
6) Are the architectural shingls a good option?
Thanks,
Ray