# Vented or conditioned attic?



## srzscz (Jun 13, 2014)

When I moved into my house (built in 1950) a year ago, I discovered the attic was full of (damaged, loose, improperly spliced) knob and tube wiring covered by cellulose loose fill insulation. This turned out to be an expensive surprise. I had the insulation all vacuumed out by an attic cleaning company and then an electrician replaced all the wiring with Romex up to the top plates, where it connects to the old K&T in the walls in junction boxes. At this point, the attic in no longer a fire waiting to happen, but there's still no insulation, and there's still leaky flex duct running all over it. (They literally used duct tape to attach it to the register boots!)

So... what do I do next? Do I 

(A) Seal the house/attic barrier with foam and caulk, put in new insulation on the attic floor, and replace all the ductwork; or

(B) Switch to a conditioned attic by closing the vents, insulating and sealing the actual roof?

Where I'm from (Holland), vented attics are rare. We always insulate at the roof, not the attic floor. But around here, they seem pretty common. 

Most of the green building folks on the net, including Lstiburek, seem to think that ducts in a vented attic are just plain wrong, and I sure ain't gonna re-do the whole ducting system through the crawl space.

At the moment, the AC system is barely keeping up at all, so I'm going to have to do something sooner or later.


What says the forum?


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## beenthere (Oct 11, 2008)

Seal attic and insulate the roof. Ducts in a conditioned space have no heat gain or loss.


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## Doc Holliday (Mar 12, 2011)

vent attic, r-8 ducts, air lock system.

so much more to this...


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## Doc Holliday (Mar 12, 2011)

first re-insulate attic.


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## cj133 (May 16, 2011)

Personally after doing a lot of research I'm more in favor of conditioned attics.

Insulating the roof makes a lot more sense especially when done properly with the appropriate vapor barrier.


Currently, my 150 year old house has a sealed attic other than normal air leaks and I have absolutely no condensation problems in the winter. I have not touched anything yet, but my plans are to insulate the roof when I get the time and money to do so. 

I'm proceeding with caution though as I do not currently have any problems and I've seen where doing modifications cause problems. I've seen pictures of both vented and non-vented attics that are disgusting nightmares.


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## mnp13 (Jan 16, 2007)

You had an electrician connect romex to existing knob and tube in your walls? Was this actually inspected? It may depend on where you live, but we were told that if you touch anything with KaT then you must replace all of it. 

We rewired our entire upstairs three years ago, because covering KaT creates a fire hazard and we wanted to insulate the attic. We air sealed with foam, then did 12+ inches of blown in cellulose insulation. We saw no reason to have conditioned space in the attic. If you're not using the attic for living space, why pay money to keep it heated and cooled?


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## cj133 (May 16, 2011)

mnp13 said:


> You had an electrician connect romex to existing knob and tube in your walls? Was this actually inspected? It may depend on where you live, but we were told that if you touch anything with KaT then you must replace all of it.
> 
> We rewired our entire upstairs three years ago, because covering KaT creates a fire hazard and we wanted to insulate the attic. We air sealed with foam, then did 12+ inches of blown in cellulose insulation. We saw no reason to have conditioned space in the attic. If you're not using the attic for living space, why pay money to keep it heated and cooled?



I too have heard K&T is fine as long as its NOT modified in any fasion, perhaps it depends on local codes? At the same time, I've also heard you can never insulate around it as it expects cooling via the surrounding air.

You bring up a good question, why heat and cool the space if you're not using it. If you have air handlers and or duct work in the attic this is enough reason to try and keep heat out of it in the summer and cool out of it in the winter.

In my situation I have an attic floor as well as a door and stairs so we use it as storage, this is a big part of why I want to insulate the roof and keep it a conditioned space. 

Also, by keeping that air space enclosed the space it self also acts as insulation to an extent. Whether or not this cancels out the effect of heat loss in the winter via the gable ends which should also be insulated and what not I have no idea.


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## carpdad (Oct 11, 2010)

I think your focus is in wrong place.
First the old wiring in the walls were not touched. This means your walls are not insulated or likely loose fill blown in around the wires. I am not sure what risk that represents, but before you spend a lot of money conditioning your attic, find out if rest of the house is adequate. Old windows and all likely draft points are bigger factors. 
I think you've fell in love )) with Listiburek (spelling sorry) ideas, but I think his ideas deal with the entire house as a interacting parts of a whole. You do one thing only, spending big money, and you are not going to see the gains that you expected from conditioned attic.
Should've kept the loose fill, seal the ducts and holes and add batts over the loose fill, spend the left over money to upgrade rest of the house.
That's my idea, anyway, and another option for people in similar situations.


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## websnooper (Jan 16, 2012)

Get the K&T out completely.


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## mnp13 (Jan 16, 2007)

Knob & Tube is perfectly safe if left alone. Insulating around it IS a fire hazard, as previously stated, K&T needs air circulation to dissipate heat, insulation prevents that. The only place we left it in our house was the over head lights in the downstairs because we didn't have a great need to pull up floor boards (that's how they installed it in the first place.)


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