Knob and Tube vs heat bill

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  #1  
Old 01-15-19, 11:22 AM
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Knob and Tube vs heat bill

Hey folks new here and had a question for you all regarding a house I just bought.
So my entire attic is covered in knob and tube wiring and I am looking to add insulation to reduce my heating costs.
currently my furnace kicks on about every 15 min or less.

so my question for you folks is would I be able to add insulation to the underside of my roof and would it even make any difference or do any good.

I have read up on knob and tube and I know you cannot put any insulation around it and replacing all of the knob and tube is currently out of the question.

thanks in advance,
kyle
 
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Old 01-15-19, 11:47 AM
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The typical attic is designed to allow outside air to flow through so adding insulation to the roof is not very helpful.
Better for now is to do air sealing which can be done around the knob and tube. Any opening in the attic floor should be addressed as that is where more of the heat loss normally occurs.
 
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Old 01-15-19, 12:49 PM
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Yes you could put insulation in the roof rafters as if you were going to "finish" the attic as additional living space.

You would also need to insulate the gables and seal the soffit ventws if any.
 
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Old 01-15-19, 01:11 PM
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Seal up the air gaps as mentioned and start saving to have the wiring replaced. In the mean time avoid heavily taxing your circuits.

---

Many of my rental houses had knob and tube when I first got them. My insurance will not cover any house with knob and tube so it all was replaced. During the re-wiring it was surprising to find the fires or near fires that the wiring had caused over the years. You could see the charred wood and smoke marks but luckily they all were shy of developing into self sustaining fires.
 
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Old 01-15-19, 02:03 PM
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If you cut the air flow on the under side of the roof you cut down the life of the roof considerable.
 
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Old 01-15-19, 03:26 PM
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I believe Joed has it right...and cutting the air flow also can create moisture problems...seem to recall they made a cardboard insert that would allow space between the insulation and the bottom of the roof sheeting, so you could add some insulation to the rafters and still have some airflow...not sure how that worked out ;o]
Mostly, would work at replacing that knob and tube...the insulation you could add with proper wiring will go a long ways towards paying the electrician...especially since so much of your heat loss is normally thru the ceiling/roof....year after year after year. Sort of getting safety on the cheap!
 
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Old 01-15-19, 05:49 PM
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Google "hot roof insulation" It is done quite often using spray foam.
 
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Old 01-16-19, 05:17 AM
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Why can't you just add insulation over attic floor joists or floor?
 
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Old 01-16-19, 05:56 AM
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He can't insulate because he has knob and tube wiring.
 
  #10  
Old 01-16-19, 07:15 AM
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Sounds like the 1920 foursquare house we bought about 35 years ago. It probably means you have no insulation in your walls either. The first project we did was replace all the knob and tube wiring, doubling or tripling room outlets, and then blow in insulation everywhere. We have been replacing leaking double-hung windows and storm windows with new as money allows. I did what AllanJ suggests and finished the attic with a trussed, 10" deep ceiling for more insulation.
Your only safe option is what has already been suggested. Seal everything! If you are in an area where wood is available, you could add a wood-burner to cut your heating bills.
 
  #11  
Old 01-16-19, 09:19 AM
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If you leave the cavities between the joist where there is wiring empty you should be fine. Laying styrofoam board over the joists leaving the bays empty should be fine. Then you can lay fiberglass bats etc over it. You could fill the bays with no wiring with insulation.
 
 

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