Jim writes from my blog host's headquarters city of Toledo, Ohio: "Our house was built in 1912. The attic has 2"X4" ceiling rafters with old cellulose poured between them. My question concerns the electrical wiring: knob and tube, Romex and the newly installed. Can wiring, especially knob and tube and Romex, be overly insulated? The wires run parallel to and across the rafters in some places and perpendicular in others. Would a layer of R-30 fiberglass be too much? Should I try to create air space over the wires and cellulose and under the new insulation? Should the old cellulose be removed first?"
In most cases fiberglass insulation can be placed directly over electrical wires. In the case of true knob and tube wiring, where the wire is not coated with a protective covering, you should not insulate over it. If you are unsure, we recommend having an electrician inspect the existing wiring.
Diane writes from Barnwell, South Carolina: "My house is over 100 years old. It has 11 foot ceilings and no insulation in the attic. We will be insulating soon but thought we'd ask the expert first... We're in the hot, humid south. Where would you recommend starting? I heard that one should lay the insulation with the paper side down (or up?) and possibly add another roll of insulation on top of the first roll except in the other direction. Is this true and can you elaborate? Thanks!"
Thank you for the question, Diane. We would start in the attic, where you are apparently preparing to start. If you are using two layers of insulation, the second should be placed across the first layer at a 90 degree angle, as you also indicate.
In high humidity areas the local building code will indicate which way the vapor barrier should face. Sometimes in your part of the country they do not use a vapor barrier and sometimes they want the vapor barrier to face the outside.
Check with your local building code for the correct method in your area.
Gene writes from Albuquerque: "Is there insulation that can be installed on a metal garage door?"
We really need to talk to you about this, Gene. We have a lot of questions to ask before we can answer your question. Please call us at 1-800-GET-PINK (1-800-438-7465).
A question from Tony: "I live in Chicago and want insulate the basement walls and then apply drywall. What is the best method to do this? Do I need a plastic vapor barrier?"
Either Kraft faced or un-faced exterior wall insulation can be used to insulate basement walls, with R-values ranging from 11 to 21. Faced insulation should be placed between the studs with the vapor retarder facing the interior of the room in heating climates. The flange on the facing can be stapled to the inside or face of the stud.
For the band joist, use un-faced, cut-to-fit pieces of insulation and place them snugly into the space.
Where local codes require a vapor retarder, we recommend a material of not less than 1 perm. We do not recommend the use of polyethylene on any below-grade walls. Vapor retarder primers are an option on drywall when using faced insulation.
Jay writes from Bettendorf, Iowa: "I am finishing 3/4 of my basement except for two rooms in one corner which will be storage. Do I need to insulate the interior walls between these storage rooms and the other rooms that are finished?"
Yes. Any wall that separates warm/cold air should be insulated. I recommend a PINK Kraft-faced insulation that can be fastened to the studs and covered with drywall or some other interior panel.
Tim writes from Buffalo: "I have a 66-year-old house in Buffalo, NY with five inches of what I believe is vermiculite (dropped-in) insulation in the attic. The insulation is 5 inches deep and not densely-packed. It is between the joists in the ceiling of the 2nd floor and the covered floor of my unheated (and unused) attic (so the vermiculite insulation is currently completely covered by nailed down flooring). I want to upgrade and save on my natural gas bills. Can I simply lay batts of Pink (R-30) across the wood floor, or do I need to pull up the floor, and lay the Pink on top of the vermiculite? Would that cause any problems (such as moisture)? Or, should I pull up the floor, remove all the vermiculite, and lay new R-19 batts with vapor barrier between the joists and then lay batts of R-30 perpendicular on top of the new R-19 batts? Thanks for any help you can offer!"
Unfaced fiberglass can go over top of the vermiculite. It can also be placed directly on the floor in the attic. Provided your attic is properly ventilated and you have normal indoor relative humidity levels in the home, I don't expect you to have any moisture problems.
