vaulted ceiling insulation

[1redTA]

the ceiling in the living room is covered with a layer of fiberglass batts for the horizontal surface and free standing insulation on the vertical portions. When I walk into the living room it feels warmer than the rest of the house. The ac thermostat, return and two outlets are all in this room.

How could I improve the insulation of the vaulted area? I want to add unfaced batts for the horizontal area but am questioning the vertical areas.
Any ideas?

 

[CombatNinja]

What is "free standing" insulation? I am having trouble figuring out what you are talking about. By "vertical" do you mean the cathedral portion.

 

[1redTA]

yeah,I say freestanding since the insulation is just resting against the 2x frame

 

[75gmck25]

In my vaulted ceiling you can see the fiberglass insulation from the attic area next to it. Some of the batts on top are nearly horizontal, but there are short vertical sections for the kneewall sections. I think my insulation is faced and then the facing is stapled on each side to hold it in place. However, I've never checked.

I believe spray foam would be the best choice, but I don't think its easy to do it yourself and get it right. The other choice would be additional batt insulation, with wire retainers on top to keep it in place. Even then, I would pull the existing insulation away from the sheetrock and verify that there is a good vapor barrier up against the sheetrock. If there are any holes for lights, receptacles or HVAC, I would spray foam around them to make it air tight.

Bruce

 

[850xpeps]

Is there an air space between insulation and roof sheating?

Is there a return air up high in your vault? If not warm air is being trapped.

 

[1redTA]

there is an air space but the return is at floor level, I keep the ceiling fan running unless the wife shuts it off for her coffee’s sake

the only vapor barrier is the facing on the batts

 

[850xpeps]

Is there ridge venting with the air space? There is a chance there isn’t enough room for air and the sun is cooking through to your living area

 

[CombatNinja]

Can you access the framing? If so, tell us what we are dealing with. 2 x 6 construction vs 2 x 8 is going to be a different ballgame. What R-value batts are already there? One problem of course is the roof needs to breathe so you need a gap between your sheathing and the insulation but that is not how fiberglass works, it has to be incased on all six sides or the R-value drops tremendously. Do you have a ridge vent on the roof and soffit vents?

 

[1redTA]

ridge and soffit vents. I believe they used 2x6s and I can access all of it. The area closet to the outside wall has probably 8-10 inches of clearance from the roof and more towards the center of the roof 4-5 feet. as far as r-value I’d have to get up there to look but I’m stuck at work till 7:30 Sun

 

[850xpeps]

Can you access the framing? If so, tell us what we are dealing with. 2 x 6 construction vs 2 x 8 is going to be a different ballgame. What R-value batts are already there? One problem of course is the roof needs to breathe so you need a gap between your sheathing and the insulation but that is not how fiberglass works, it has to be incased on all six sides or the R-value drops tremendously. Do you have a ridge vent on the roof and soffit vents?

Fibre glass insulation does not need to be enclosed on all 6 sides. If it’s only r20 then part of the problem is not enough insulation to keep the heat from the sun out. It sounds like his vaulted roof is trusses not joists. Which is good as he has plenty of room for ventilation if I understand what he is saying. If 5’ of room is there at the peak and only r20 then I’d suggest adding more insulation.

 

[stm317]

Older cathedral ceilings typically just don't have the space for adequate insulation. Since there's such limited space, your best bet is to get as much R value out of it as you can. Fiberglass is usually around R 4 per inch of thickness. Polyiso rigid foam has an R value around R7 per inch and XPS foam is around R6 per inch.

So if you currently have 2x6 framing with 5.5 inch fiberglass batts you've got about R19. Polyiso at equal thickness would be R35ish, which is an 84% improvement in R value.

 

[strutaeng]

Older cathedral ceilings typically just don't have the space for adequate insulation. Since there's such limited space, your best bet is to get as much R value out of it as you can. Fiberglass is usually around R 4 per inch of thickness. Polyiso rigid foam has an R value around R7 per inch and XPS foam is around R6 per inch.

So if you currently have 2x6 framing with 5.5 inch fiberglass batts you've got about R19. Polyiso at equal thickness would be R35ish, which is an 84% improvement in R value.

Yes, 2x6s give an R-19 with fiberglass. That was okay back in the 1980s. The current codes require R30/R38 minimum.

There are different ways to add additional insulation, each varying in cost and .

Option 1: tear off gypsum board, remove fiberglass batts and apply spray foam to achieve the R-30/R-38 rating. Reinstall ceiling gypsum board

Option 2: Remove roof shingles and add rigid insulation on top of the deck, add new deck and new shingles. How old is your roof? It's something like this: https://buildingscience.com/documents/insights/bsi-063-over-roofing

Option 3: Add rigid insulation to the underside of the gypsum board ceiling. Add new furring strips and new gypsum board. You'll lose some head clearance, but not much.

I hope this helps.

 

[1redTA]

thanks for the input, I’m getting some info together for when the attic space is tolerable to do the actual work

Art