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Old 04-28-2010, 03:26 PM   #1
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Knob and Tube: Can I insulate over it?


Hi. I'm remodeling my basement and have the entire ceiling exposed. I would like to insulate the basement ceiling to sound proof. There was no prior insulation. I purchased HALO IC rated cans so I know I can insulate around them. I have random runs of K&T wiring mixed in with some newer Romex I had installed. The K&T is still active in parts of the house. Can I install insulation around K&T? If so are there any precautions or steps I should take prior to doing so? If I have a run of K&T going lengthwise do I split the insulation and place it between batt fold or work it under the wiring?

Thanks in advance for any advice,
-Dave

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Old 04-28-2010, 03:55 PM   #2
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Knob and Tube: Can I insulate over it?


Where are you located ?
Usually no - you can't
But several states allow it now as long as the K&T is inspected by an electrician 1st & passed

Myself I'd get rid of the K&T before I finished the basement

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Old 04-28-2010, 04:08 PM   #3
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Knob and Tube: Can I insulate over it?


I'm in Portland, Oregon. The majority of homes here are older bungalo type homes (1920's). I would like to replace but I think that might break my budget. So it is ok to run the insulation over/under let's say Romex?
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Old 04-28-2010, 04:35 PM   #4
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Knob and Tube: Can I insulate over it?


Romex is fine to insulate around

Read up on what is allowed for your area for K&T:

http://www.ohcs.oregon.gov/OHCS/CRD/...ion1_Attic.pdf

Some info:

Quote:
1.10 Knob and tube electrical wiring is often found in the walls and attics of older homes.
The possibility that insulation may trap heat produced by overloaded knob and tube wiring circuits requires insulation shall be kept 3 inches away from any live knob and tube wiring. Depending on agency policy, Oregon Building Code allows insulation to be installed over, around or in contact with knob and tube wiring if the following conditions are satisfied. (Oregon Building Codes Division, Temporary Rule effective January 1, 1993; Amends Part VI of the 1990 Edition of the Oregon One and Two Family Dwelling Specialty Code).

1.11 An unfaced fiberglass batt of highest R-value possible shall be placed under the knob and tube wiring. If knob and tube wiring exists in an attic space and is known to be dead (verified and documented by a licensed electrician) then the wiring may be covered by insulation.

1.12 A licensed journeyman electrician or a certified electrical inspector shall inspect all visible knob and tube wiring. This includes repairs, alterations or extensions to the electrical system.
A. All defects found during the inspection shall be repaired prior to the installation of insulation.


B. All knob and tube circuits shall have over-current protection in compliance with the 60
C column of Table 310-16 of National Fire Protection Agency (NFiPA) 70-1 990. Over-current protection shall be 15 amp circuit breakers or Type S fuses. The Type S fuse adapters shall not accept a fuse of an imparity greater than that permitted in this chapter.


1.13 Fiberglass and cellulose insulation are acceptable for use in contact with approved knob and tube wiring. Foamed-in place insulation shall not be used with knob and tube wiring.

1.14 Non-soldered exposed splices or connections shall be protected by installing solid flame resistant enclosure, securely attached with at least 3-inch clearance from insulation.

1.15 When existing knob and tube wiring will not be upgraded as required it shall not be covered. Two options are:
A. Insulate below with nothing above. Maintain a minimum 3-inch air space to the sides of the knob and tube wiring.


B. Insulate below and tent or lid with a baffle 3 inches above. Baffle the knob and tube wiring and blow loose fill insulation in the remaining areas of the attic, or install insulation in the attic area (not over the knob and tube wiring). The baffling material shall have a flame spread of 25 or less
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Old 04-28-2010, 04:46 PM   #5
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Knob and Tube: Can I insulate over it?


Thanks so much! Sounds like with a little work it's doable.
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Old 04-28-2010, 05:56 PM   #6
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Knob and Tube: Can I insulate over it?


I'm an electrician working in Portland. The company I work for does lots and lots of work in old Portland houses. Our recommendation is always to demo and refeed runs of K & T when ever possible. It's especially important to do it while you have open access. If you need an electrician to come certify and document the integrity of the the K & T, you might as well have them refeed it instead. Then you're good for the next 100 years.
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Old 04-28-2010, 06:12 PM   #7
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Knob and Tube: Can I insulate over it?


Thx Jupe Blue. I'll see what the electrician I'm working with will charge to replace the remaining K&T. To be honest I'm also thinking I may just cut out the area where the insulation would come near it and give it that 3" recommended clearance.

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