Adding insulation in attic and garage - with images


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Old 01-25-22, 09:52 AM
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Adding insulation in attic and garage - with images

Hi,

Im in Cleveland Ohio and we are having our colder temps of the year and head some heavy snow over the last week. I have noticed that I have a lot of icicles/ice dam at my gutters so I started looking at insulation.

Ive created two crude images to show my current insulation of my 1970s home.

My home is a bungalow with two bedrooms and a bathroom upstairs/in the attic space. I do not believe I have a ridge vent because of how the slopped roof joins the flat/shed roof of the bedrooms. Where the attic access panel is there is no ridge vent visible. There is a gable vet in the attic space at one end of the house.

House insulation
1. My zone recommends a minimum of R38. I cannot achieve that based on the 2x6 rafters and the space that I have and the budget I have. From what I understand the thickest batt I can put in the rafters is R21. Is it worth going from R8 to R21?
2. Should I go with R30 and compress it into the space?
3. given that I do not have a ridge vent. Do I need to run rafter vents? and if I do do they need to extend into the attic space where the gable vent is?

Garage insulation
Above the garage is an attic with storage. There is only one area of the garage attic with insulation which is the wall of the bedroom (R8 batt).
There is no insulation between the rafters or the ceiling joists.
The garage does not have HVAC.
1. How should I go about insulating the garage to keep the garage space warmer?
add insulation between the joists or rafters
Its just barely warmer than outside at the moment.

I know this is long but hopefully I have provided all relevant info




 
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Old 01-25-22, 10:45 AM
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Are the rafters exposed? Are you taking down ceilings? Solid or sprayed foam could give you the R38 rating you are looking for. If you are planning a roof replacement soon, solid foam insulation boards could be added on top before re-roofing.

If there is no conditioning in the garage there is little value to insulating it. The only heat source will be what transmits through the wall and ceiling from the heated house. Insulation in the garage ceiling is needed if there is living space above to keep that space warm. Not required for storage.
 
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Old 01-25-22, 10:54 AM
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1. Going from R8 to R21 is a huge improvement. It is not enough but it is much better than R8.

2. You will have a very difficult time installing the correct batts. I have no idea how you will compress and install higher R insulation. Spray foam would be worth looking into.

3. Your house already isn't up to current codes for insulation or attic ventilation. Do you want to open that can of worms now? Plus, I doubt you would see a noticeable change in anything. In a perfect world you would have enough room between the interior heated space and roof sheeting for a nice air gap between the insulation and roof. I doubt you'll get enough new ventilation to make it worthwhile unless you decide to sacrifice insulation.

GARAGE
1. Put whatever money would have gone to garage insulation into doing a better job insulating the heated portion of the house. In your climate, without additional heating the garage will be expensive to keep warm. You might have a chance if you never open the doors but with no source of heat it will still get cold insulation or not. Insulation only slows the movement of heat. It won't keep your garage warm. It will just make it get cold slower.
 
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Old 01-25-22, 10:59 AM
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House insulation
Is it worth going from R8 to R21
R8 is practically nothing, heat path goes up, out, then down so it will help but assuming you have finished rooms a lot of tear up is going to happen

Should I go with R30 and compress
Compressed insulation decreases R value

Do I need to run rafter vents
In a cathedral ceiling you don't have the space

Garage insulation

​​​​​​​How should I go about insulating the garage
So typ you dont insulate un-conditioned spaces. But I have had several garages that were fully insulated and it does help the house. I only did that because they were new construction, the crews were there and maybe I would have added heat at some time.
 
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Old 01-25-22, 11:15 AM
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Thanks for the responses.

The rafters or not exposed. I do not want to tear interior drywall to install this. from the attic above the bedrooms it may be possible to slide rafter vents down to the storage area behind the R8 insulation that is there. Of course it may tear this insulation as I slide them in.

I believe another option would be to switch how its insulated? Am I correct in saying tat its currently insulated to make that storage space within the heated potion of the house?
What if I removed the R8 insulation from the rafters in the storage area and installed new install in the joists one the room below and the knee walls of the bedrooms?
I could get at least R38 between the joists but the walls I think are 2x4 construction.

Would this provide with better insulation for the home and prevent the ice dam that I have going on and prolong the roof?

I had a new roof put on in 2020.
 
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Old 01-25-22, 11:21 AM
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like this.
 
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Old 01-25-22, 12:33 PM
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My neighbor across the street seems to have the same design to his house you do. He decided the best option was a roof rake and to make sure there is as little snow on the roof as possible.
 
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Old 01-25-22, 01:51 PM
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I don't understand how you propose to add insulation above the bedrooms. Is that the roof or is there attic space above?

I had a similar situation as your small storage space behind the knee wall. When I was having other spray foam work done, I had that area spray foamed as well and made it conditioned space. It helped reduce roof melting above it.
 
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Old 01-25-22, 02:32 PM
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You cant slide insulation between rafters up a ceiling!

There are companies that can inject foam or celulose into existing insulated spaces but all I've ever seen are the commercials.
 
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Old 01-25-22, 09:53 PM
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There is a small attic space above the bedrooms. It has a slope to it I'd guess at most 10 inches at its narrowest to 30 inches at its widest.

I was not suggesting sliding insulation between rafters but sliding the plastic rafter vents in there.
if you look at the last image I posted imagine that the red line are the drywall on the ceilings and walls.
Or could I remove the R8 that is in this section, slide in the rafter vents and then use blow in insulation to fill that void? Given that its a 5.5 inch space what R rating would that section be?

The idea being so that the roof had adequate outside air passing over it to prevent the ice dam and would also allow me to keep that storage area conditioned

I shall look into a snow rake.

Thanks for everyones input
 
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Old 01-26-22, 07:47 AM
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Rafter vents will do nothing unless there is air flow between them and the roof. If you do not have sidewall or soffit vents and a ridge vent (or open attic space to gable vents) to allow air to pass over the rafter vents then they are useless. Blown-in insulation (or foam boards) above the existing insulation in the available attic space over the bedrooms is possible and will increase the existing R value.
 
 

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