Home>Discussions>INSULATION & HVAC>Insulating void space, flat roof with balloon structure
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JTNuck
Insulating void space, flat roof with balloon structure

I am looking for some help. I am residing in Southeastern PA and I reside in a 60 year old end unit. It's a brick structure with balloon framing. I need to insulate the "attic" space. It's approximately 400 +/- square feet. I can only assume that blow in insulation is preferred only because it had been used prior, but it's old and settling and missing in areas. Do I blow it in a fill as much of the space as possible or do it just fill the ceiling joist area. Also do I need to be careful not to cover the wall stud spaces as to let the air circulate or can I/should i fill that space too?

Thanks to all in advance

keith3267
Re: Insulating void space, flat roof with balloon structure

Is there an attic? Are there separate ceiling joists and rafters? If there is an "attic", how tall is it?

If the unit is 60 years old, that means it would have been built around 1952. Balloon framing was no longer being used by that time. Whether it is balloon framing or not, you can fill the wall spaces with insulation, but I doubt it will settle very far. Building codes usually required fire blocks by then.

JTNuck
Re: Insulating void space, flat roof with balloon structure

the ceiling joists are 2x4 and the roof joists are 2x10, I believe. The highest end is about 12" space, not including the ceiling and roof joist height and the low end, the roof joist sit right on the ceiling joist. No keep in mind I'm not a contractor, I can only describe what I think I see. My verbiage may nit be correct. On one my concerns is having snow and ice form on the roof if I do something wrong when blowing this stuff in. I had several estimates and it's just insanely higher than the DIY price from my local big box and not one estimate comes with a warranty.

Timothy Miller
Re: Insulating void space, flat roof with balloon structure

Howdy this is a great time to get some estimates. A closed cell foam might give you the best for the $ with limited space and then have cellulose blown in on top of it. The out side walls have a void at the top? What do the roof joists rest on?. You might want to add insulation to the walls but with brick issues with it being able to wick out water or not so again a great time to have a contractor actually several come look an advise you. At the least consider putting some Roxal, it does not give off as many itchy fibers as some competitors rock wool, insulation over the wall voids- it has a great fire rating and cuts like bat fiberglass. Adding rock wool or a 2 by4 or 6 on top of the wall void is to stop chimneying or any fire gas/flame. Moreover. to stop convection of air that sucks the heat or cool out of the house with it depending on the time of year.

keith3267
Re: Insulating void space, flat roof with balloon structure

This sounds like it will be a very difficult job to do. It is hard to give advice because I don't know how the "attic" is ventilated. At the very least, you want to fill at least a couple of inches above the ceiling joists. Exposed ceiling joists will act like radiator fins sucking the heat out of the room below.

You do not want to insulate all the way to the underside of the roof, but you might be able to insulate up into the roof rafters a little. It depends on the ventilation system.

Does the roof overhang the wall? How much? Are there vents in the overhang? Is your unit a two (or more) story?

JTNuck
Re: Insulating void space, flat roof with balloon structure

No, it does not over hang. It does have a Mansore roof on two sides. The back on the house has two vents built into the wall, the same dimensions of a brick. I also has a TPO roof installed and the rear of the house has a standard roof vent and the front has a fin style vent that spins when its breezy.

keith3267
Re: Insulating void space, flat roof with balloon structure
JTNuck wrote:

No, it does not over hang. It does have a Mansore roof on two sides. The back on the house has two vents built into the wall, the same dimensions of a brick. I also has a TPO roof installed and the rear of the house has a standard roof vent and the front has a fin style vent that spins when its breezy.

Did you mean Mansard roof? I am not familiar with a Mansore roof. A Mansard roof has to go all the way around the house, not just on two sides. Could you have a Gambrel roof instead? That would be on two sides only.

The back of the house and the rear of the house, are they not the same thing? I am not familiar with TPO roof.

JTNuck
Re: Insulating void space, flat roof with balloon structure

I suppose it's a mansard roof. It goes across the front and side, as I said it's a end row. Their is also a parting wall between the neighbor and myself. The TOP membrane is a loose lying membrane that is mechanically fastened at he seems. I don't know a lot about it the roofer talked me into it with a 20 year warranty and being maintenance free. Seeing I need a 32 foot ladder to get on my roof I thought it was the best option.

JTNuck
Re: Insulating void space, flat roof with balloon structure

Very sorry, I meant to type TPO membrane nit TOP membrane

keith3267
Re: Insulating void space, flat roof with balloon structure

I'm still trying to get a picture in my mind. You have a Mansard facade on the front and end walls for the second story of the unit. The rear does not have a Mansard facade. Is there an eave on the back side? If so, are there any vents in the eave? If no eave, then there should be a facia board and maybe it would have vents.

Now for the roof. Does it have a ridge in the center or does it slope from the front to the rear with no ridge in it? The standard roof vent in the rear, is that just a pipe sticking straight up, 3 to 4" in diameter? If so, that is the DWV (drain waste vent) and is not part of the attic ventilation.

JTNuck
Re: Insulating void space, flat roof with balloon structure

It has the mansard on the front and side. The parting wall is what I believe is called a pa****t wall. The back is flat. no eaves or overhangs. There is a facia that goes the back side and front which amounts to a 2 x 10 or so with aluminum for looks. The roof slopes back to front no ridge. Their are vent stacks for drain waste. One that runs up the parting wall along with the gas furnace chimney and another along the rear wall where the previous owners installed a half bath in the basement and ran a designated vent. I have two attic vents. If you can divid the roof area in thirds, I have a basic vent in the rear third of the roof, say left of center if looking at the front to the rear, and the other is an aluminum finned vent that spins to vent out, located in the front third also to the left of center. The reason it off the center line is their is a skylight installed in the bathroom for ventilation and they wanted to space things out.
The vents in the wall are in the brick wall itself. Their is no eves or overhangs to vent. The Mansard basically is vertical in the back and sits back off the wall about 16 -18" and is about 3' high, pitches down and out as a traditional pitched roof does and runs just proud of the facia on the walls for run off.

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