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hvacjesse
Spray Insulation and preservation of my ridge vent
hvacjesse

Hello All,
I am not a insulation pro, this would be a DIY project on a tight budget and my main goal is to try and make my home more efficient. I live in Brooklyn NY and the winters are brutal and the summers can be equally brutal.

I have an unfinished attic and its also uninsulated. Yes this winter was brutal !!!. It is ventilated with a ridge vent system. I would like to preserve this as my understanding is that its an effective deterrent of ice dams. The house was also built pre-1900 so my rafters are 24"OC.

My thinking is that I can purchase, from Home Depot, foam roof baffles and use that to preserve my ventilation from soffit to ridge, as pain staking as this would be I think its important.

Then I can spray a good layer of spray foam to achieve a air nice seal and then finish the insulation with R-38 craft faced batts.

Giving me around R-49 for the roof which would be code compliant in my area.

Does this sound right? I understand it would not be typical but I cannot survive another winter like what just past.

I do not want to break my roof to insulate from above, the roof is practically new, the previous owners installed it 5 years ago.

Any help would be greatly appreciated. Thanks so much.

ed21
Re: Spray Insulation and preservation of my ridge vent
ed21

I don't understand where you are trying to insulate and how you are going to end up with R-49.
Typically the attic is insulated on the horizontal rafters. Maintaining the venting at the soffit is important.
While the code for new may say R-**, it doesn't mean you have to do that.
R-38 unfaced batts placed between the rafters would help a lot. Thicker than 12" fiberglass batts if available would work too. You could also use batts of the thickness of the rafters and then lay additional batts perpendicular to the rafters. A lot of more work. Many people in your situation might blow in insulation, but I personally don't care for it.
Soffit venting is still important.
This means you have to give up any storage or use of the attic.

ordjen
Re: Spray Insulation and preservation of my ridge vent
ordjen

The baffles are mainly to prevent accidentally blocking the eave vents, especially when blown in insulation is used. If you run the baffles all the way to the ridge vent and then seal them in with spray foam, you have essentially sealed the area and the attic is now part of the house envelope. This is fine if you intend to use this as living area or storage.
However, if you are intending to just get good insulation, just use the baffles at the eaves, lay down your fiberglass insulation and leave it at that. If you now don't have any insulation at all up there, you will notice a dramatic increase in comfort, both summer and winter, and a reduction in your utility bills.

Before the fiberglass goes down, go around with cans of spray foam and close all gaps formed where plumbing, vents and electrical lines penetrate the ceiling. These openings function like miniature chimneys, sucking conditioned air right out of your house.

A home built pre-1900 will likely have balloon frame construction with uninterrupted wall cavities from the basement to the attic. This is not desirable from either an energy standpoint or for fire protection. Without fire stops in the wall, heat and fire can run right up the wall cavities.

An amusing story is how my father decided to try to insulate the walls of his pre-1900 apartment house in Duluth, Minneasota. He crawled into the attic and began to pour loose insulation into the wall cavities. After several bags, he figured something was not right! He went down the basement and there was all the insulation piled up on the basement floor :) This is the problem you possibly face too! Even if you don't insulate the walls, you want to seal those wall cavities to prevent the chimney effect from sucking conditioned air from every little void in the house walls and ceiling planes.

keith3267
Re: Spray Insulation and preservation of my ridge vent
keith3267

What you are planning to do is not going to increase your efficiency or save you any money. You insulate your attic floor. If you have flooring in your attic, you will need to take it up and insulate between the joists. You will probably find some insulation in there now, at least 2" as at the turn of the century, this insulation was added so that the builder could use a smaller furnace to heat the house. At that time, the was the most cost effective solution.

Once you have taken up your attic floor, you will need to decide whether or not you intend to use the attic for storage. If not, you can throw away the attic flooring and insulate up to 12" thick going above the joists. If you have 6" joists (2x6), you can use two layers, one 6" batt between the joists and another 6" batt running perpendicular over the tops of the joists, or parallel to the joists but offset from the lower layer.

If you want to use the attic for storage, then you have to decide to limit the insulation to the depth of the joist by either giving up some R value or by having a closed cell foam professionally sprayed, or adding joists on top of the existing joists to deepen the joist cavity.

Mastercarpentry
Re: Spray Insulation and preservation of my ridge vent
Mastercarpentry

In attics where more insulation is wanted without losing the storage space, my solution is to insulate to the top of the existing ceiling joists, then cross-lay additional joists on top of that insulating between them. This better distributes the load from the attic floor to the original joists, reduces the thermal path between both joists to almost nothing, and the only real issue is the possibility of needing to create an extra 'step' at the attic stairs by setting one of the added joists back from the opening. To get the most from this system use IJT's instead of solid joists as they are much lighter and cheaper for any given width.

Phil

hvacjesse
Re: Spray Insulation and preservation of my ridge vent
hvacjesse
ed21 wrote:

I don't understand where you are trying to insulate and how you are going to end up with R-49.
Typically the attic is insulated on the horizontal rafters. Maintaining the venting at the soffit is important.
While the code for new may say R-**, it doesn't mean you have to do that.
R-38 unfaced batts placed between the rafters would help a lot. Thicker than 12" fiberglass batts if available would work too. You could also use batts of the thickness of the rafters and then lay additional batts perpendicular to the rafters. A lot of more work. Many people in your situation might blow in insulation, but I personally don't care for it.
Soffit venting is still important.
This means you have to give up any storage or use of the attic.

I am trying to insulate the underside of the roof, but my understanding is that several factors have to be considered.

1. mold
2. venting
3. fire protection

to my understanding

The mold is prevented by using inorganic matter as the insulating material, the foam, to create a good seal.
The venting is there I was just wanting to check if my concocted way of doing it was correct.
The fire protection is taken care of with the finishing sheet rock.

My R-49 value is coming from spraying the underside of my roof with R-7/inch foam and do around 1 1/2 inches then once that cures put up the R-38 craft faced batts.

The ultimate goal is too have more living space, not a separate apartment per say, just more space that is usable and not a proverbial icebox.

Thanks for the reply.

Sombreuil_mongrel
Re: Spray Insulation and preservation of my ridge vent
Sombreuil_mongrel

The little baffles made from styrofoam egg carton material are marginally effective because they do not allow any circulation where they are stapled down. If you do decide to insulate the roof rather than the ceiling, get some rigid foam board and fit it between the rafters leaving a 1" space for ventilation, then have the whole mess coated with foam, which seals and still gives full venting from rafter to rafter. This DIY-able part of the work will also save you money on the spray foam bill.
Casey

hvacjesse
Re: Spray Insulation and preservation of my ridge vent
hvacjesse
ordjen wrote:

The baffles are mainly to prevent accidentally blocking the eave vents, especially when blown in insulation is used. If you run the baffles all the way to the ridge vent and then seal them in with spray foam, you have essentially sealed the area and the attic is now part of the house envelope. This is fine if you intend to use this as living area or storage.
However, if you are intending to just get good insulation, just use the baffles at the eaves, lay down your fiberglass insulation and leave it at that. If you now don't have any insulation at all up there, you will notice a dramatic increase in comfort, both summer and winter, and a reduction in your utility bills.

Before the fiberglass goes down, go around with cans of spray foam and close all gaps formed where plumbing, vents and electrical lines penetrate the ceiling. These openings function like miniature chimneys, sucking conditioned air right out of your house.

A home built pre-1900 will likely have balloon frame construction with uninterrupted wall cavities from the basement to the attic. This is not desirable from either an energy standpoint or for fire protection. Without fire stops in the wall, heat and fire can run right up the wall cavities.

An amusing story is how my father decided to try to insulate the walls of his pre-1900 apartment house in Duluth, Minneasota. He crawled into the attic and began to pour loose insulation into the wall cavities. After several bags, he figured something was not right! He went down the basement and there was all the insulation piled up on the basement floor :) This is the problem you possibly face too! Even if you don't insulate the walls, you want to seal those wall cavities to prevent the chimney effect from sucking conditioned air from every little void in the house walls and ceiling planes.

You got it that is exactly what I hope to accomplish. I bought that IR camera case for my iphone and I would literally see my 2nd floor heat rising to escape out the attic. Granted it was one of the coldest winters on record but I was literally burning $300 a month.

Its funny you mention that I actually did have loose cotton blown in my walls and ceiling at some point, I found this out when i discovered that there is one cavity wall that was used to run all the electrical during a past renovation. I guess the contractor had blown out a few walls and all the cotton came out so they put some crappy R-11 batts in places in the walls and ceilings but I recently opened up a lath wall and saw what they did was run electrical up 2 flights to avoid having to break walls, probably because they had already put them up and not ran electrical.

Needless to say electrical is an absolute mess here and is on the to-do list as well.

Thanks for the help

hvacjesse
Re: Spray Insulation and preservation of my ridge vent
hvacjesse
keith3267 wrote:

What you are planning to do is not going to increase your efficiency or save you any money. You insulate your attic floor. If you have flooring in your attic, you will need to take it up and insulate between the joists. You will probably find some insulation in there now, at least 2" as at the turn of the century, this insulation was added so that the builder could use a smaller furnace to heat the house. At that time, the was the most cost effective solution.

Once you have taken up your attic floor, you will need to decide whether or not you intend to use the attic for storage. If not, you can throw away the attic flooring and insulate up to 12" thick going above the joists. If you have 6" joists (2x6), you can use two layers, one 6" batt between the joists and another 6" batt running perpendicular over the tops of the joists, or parallel to the joists but offset from the lower layer.

If you want to use the attic for storage, then you have to decide to limit the insulation to the depth of the joist by either giving up some R value or by having a closed cell foam professionally sprayed, or adding joists on top of the existing joists to deepen the joist cavity.

Yes you are correct, the boiler was the first thing that I did when I took possession, it was way too small. These houses where typically used as spring-summer-fall bungalows. They would be closed up for the winters.

There definitely is cotton blown insulation below the floor of the attic, which is a beautiful red oak t&g, I plan to pull up and insulate as well. As I say to a previous post I am looking for more living space and before doing upgrades like electrical and HVAC as the house needs as well I figured I better get the the insulation done..

Thanks for the reply

hvacjesse
Re: Spray Insulation and preservation of my ridge vent
hvacjesse
Sombreuil_mongrel wrote:

The little baffles made from styrofoam egg carton material are marginally effective because they do not allow any circulation where they are stapled down. If you do decide to insulate the roof rather than the ceiling, get some rigid foam board and fit it between the rafters leaving a 1" space for ventilation, then have the whole mess coated with foam, which seals and still gives full venting from rafter to rafter. This DIY-able part of the work will also save you money on the spray foam bill.
Casey

I have thought of that as well, the problem was when i priced it. The rigid foam is so expensive on a per sheet basis. I would need over 1400 bf which was something like $2300 in foam. As opposed to $2.39 for each of the baffles, I am not even really sure that what they are called, they look like steel roof decking so they definitely have a nail or staple edge.

Thanks for reply

hvacjesse
Re: Spray Insulation and preservation of my ridge vent
hvacjesse
Mastercarpentry wrote:

In attics where more insulation is wanted without losing the storage space, my solution is to insulate to the top of the existing ceiling joists, then cross-lay additional joists on top of that insulating between them. This better distributes the load from the attic floor to the original joists, reduces the thermal path between both joists to almost nothing, and the only real issue is the possibility of needing to create an extra 'step' at the attic stairs by setting one of the added joists back from the opening. To get the most from this system use IJT's instead of solid joists as they are much lighter and cheaper for any given width.

Phil

I am not sure I follow. Would I be preserving my vent? How would i hang sheet rock over all that, wouldn't I be losing all that, 2x8, head space?

Thanks for reply

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