Blown-in insulation and old wiring


Old 01-21-02, 02:56 PM
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Unhappy Blown-in insulation and old wiring

The fact is, and it's no surprise, my house has no insulation in the walls. The house was built in 1925 and still has old tube and wire wiring. In speaking with another individual who looked into having insulation blown into their walls they received less than promising advice:

1. Doing such poses a fire hazard. Unless, all the wiring is updated. Blah!
2. Furthermore, this would be such a fire hazard that come time to sell the house, I wouldn't be able to since this fire hazard would standout like a sore thumb when the buyer has the house inspected. Another, Blah!

This seems extreme! Is it true? Should I have insulation blown-in? Or, not? If so, is fiberglass safer with old wiring. Please help! Thank you.

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Old 01-24-02, 05:21 AM
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Knob and Tube are isolators and not insulators. They are designed to prohibit the wires from touching anything. This is the problem with putting insulation in walls that have knob and tube. The other problem is the age of the wiring, it must be over 50 years old. This will raise concerns for insulating contractors, perspective buyers and even mortgage and insurance companies.

This does not mean there is any present harzard to you. What it does mean, you will find it difficult to find a contractor to insulate, they will not wish to take on the extra liability if something happening because of it. A perspective buyer would probably use it to negotiate the price of the house. Mortgage and insurance companies would use it to determine what rates and/or premiums they should give you.
Old 01-31-02, 05:18 PM
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Thank you for the reply! I have a much better idea of what I'm in for.
Old 02-03-02, 05:37 PM
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Another Option

You could add insulation board to the outside of your house, under the siding... It's just an idea if your not going to rip up your wall's to up-date the wiring..

Old 02-08-02, 08:19 AM
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My previous house was an 80 year old, 2 story, (lower level brick exterior, upper level cedar shingles)1500 sqft, in the Detroit MI suburbs. When I bought it, it had no insulation in the walls, very little in the attic, knob & tube wiring, an old 8 fuse fusebox, steam boiler heat with the big iron radiators.

One of the best things we did was to have cellulose insulation pumped into the walls and more into the attic. That next winter our heating bill was around half, the house felt warmer overall and outside noise was considerably reduced. We got 5 or 6 quotes from a low of $900 (he seemed to be a crook) to a high of $2,200. This was in 1992 and we chose a $1,400 bid. Between the studs, on the lower level they drilled within the mortar lines to pump in the cellulose, on the upper they cut a shingle right where it goes under the one on top of it, then drilled through the sheathing, and pumped it in. When they were done refilling the holes & patching, you could not tell where they worked.

I understand your concern with the knob & tube, mine was in good condition, but I replaced it anyway, prior to the insulation job. I replaced the K&T myself, with the help of an electrician who taught me how. He did it as a side job & I think more because he liked to help people learn. I did all the hard, time consuming, and dirty work, he did the new breaker box and its connections. Wiring is not difficult when you understand the basics. If you are handy & willing to learn, you could probably do it with someones help. In any event, how many electicial outlets do you have on exterior walls? Most of mine were interior walls. If not many, and if most are on the first floor and accessible from a basement, maybe you could just replace the parts that go up those exterior walls. Use the search funtion of this site to look-up old posts from me or on this subject. I posted one last year about K&T, and my replacement experience.

If you are going to replace the wiring do it this winter while it is still cold outside. The attic is no fun in the summer. Then later this year after you finished the wiring have the insulation pumped in. The insulation job made my house a lot more comfortable and probably paid for itself from the heating bill savings within just a few years.

Good luck, keep us posted. Mike
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