Southern PA/DE - Attic Insulation

LifeIsGood169

Hi, I live in southern PA [zone4] and I am having problems cooling my house [built in 2008]. After a lot of research, I'm looking to prioritize my next insulation steps. But I am unsure of the best way to proceed.

Background:

• Currently my house, by interior wall temp, is about 72F in the Basement, 80F 1st floor, and 85F 2nd floor at about 3pm with an outside temp of 98F.
• Our 1 large A/C was serviced a month ago with no leaks/etc, but it is probably too small for the 3,500 sq. ft. home (most neighbors have 2 smaller units).
• I can tell my insulation is not as good as past houses and so I'd like to hold off 2 years before I replace the A/C unit (currently 10 years old).
• I am an avid diy-er (put in stone walls, indoor/outdoor plumbing, electrical boxes/breakers, waynes coatings, molding, siding, decks, insulation rolls, tile backsplashes, etc.)
• I have tons of tools: air compressor, radial arm saw, router table, infrared temp gun, etc.
• I've mapped out my house room by room with temp differentials leaving me with a few options.

1) Above 3 car Garage - Unfinished, Uninsulated, Non-living room (approx size of bedroom with exposed roofing)

• I've got soffit vents (plastic + mesh) on one side (122F roof temp at shoulder level) and plain thin white plastic on the other (138F roof temp at shoulder level - driveway side [south facing])
• rift vent up top (138F - 149F)
• The living space adjacent looks to possibly be insulated with 1/2 plywood and maybe 2 inches of yellow/white fiber glass looking stuff (wall temp unfinished side = 116F), (wall temp finished side (bathroom) = 92F-93F)
• The cut out to enter the room is uninsulated 95F on the painted side - (approx 1/4" plywood) and located in the bathroom closet (door temp 88F)

Questions

• Do I insulate/ventilate this room? Which provides most benefit if any?
  • extra soffit vents, gabble vents, radiation barrier, blown in, foam, or just on the wall separating the conditioned bathroom

2) Redo duct work and insulate ducts + sheath the return lines which are just in between drywall and 2x4's right now.

• harder for me personally and would need to check air temps along ducts to estimate the advantage

3) Attempt to insulate the rest of my attic which is pitched, but contains much smaller spaces above the other 2nd floor rooms (approx. 3ft gaps - unknown insulation level)


4) Find the highest spot in roof (approx 150F) and install solar powered fan?


5) Redo rift vents (bigger?)


6)What type of insulation is best for my shallow roofing above 2nd floor rooms (recommended R-38 +)? What is the best way to seal the 2 attic entrances? (pink styrofoam stuff - silicone glue - plywood door?)



My current guess:

• increase soffit passive roof vent space
• possibly install gabble vent in spare room
• add radiation barrier (staple gun to rafters (6" away from roof))
• attach more insulation between conditioned / unconditioned spaces
• leave uninsulated room above garage uninsulated aside from the radiation barrier

Thanks for all help. I can post pictures / dimensions if needed.

Windows on Wash

Pictures are helpful in cases like this.

Get on Building Science.com and start researching.

They have a pdf and answer for every question you have.

In a nutshell...

• skip the attic fan
• rigid foams work great on attic doors
• seal and insulated any duct work outside the envelope
• seal all the top plates and penetrations
• blow in insulation to R-50
• make sure soffits are baffled and unobstructed

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LifeIsGood169

Thanks. The PDF diagrams on the BuildingScience website help a ton.


edit:
Ok I think i've got my air seal design down.

Where do you recommend buying foam board, insulation blower, radiation barrier, and soffit vents? Right now, it seems like my most reasonable bet is with Home Depot.

LifeIsGood169

I hate to pester, but I came across another potential problem while examining my existing soffit vents.

It appears the standard soffit vents I have installed and the ones I can buy at home depot have about 15% of their sq. ft space ventilated. The other 85% could be considered solid plastic. Taking this into account there is no way I have the 1 sq. ft. per 300 sq. ft. of ventilation area that is recommended. Also, I have yet to see a good mesh/screen type design. Most designs are plastic with raised and slightly covered holes leaving little true ventilation area.

Questions
1) How hard is it to replace soffit vents and what do you guys recommend to keep bugs out but still ventilate well?
2) Is there another way to check for adequate attic ventilation other than measuring soffit and or ridge line ventilation area (perhaps an air speed sensor or temp recomendation etc)?


Thanks again.

Windows on Wash

Glad to see you did some research.

Home Depot/Lowes are fine for the foam board.

I would not use their cellulose for blown in work (they carry the cheaper stuff that is ammonium sulfate stabilized vs. the borate only stuff (a bit more premium but far better = no off gassing).

Soffit vents are fine. I am not sure what route you are going on this though.

The better soffits are available via building supply houses and the Alside Charter Oak soffit is my favorite.

We usually use a full vented vinyl soffit as compared to singular soffit vents.

Most of the soffit vents (single units) have a screen mesh to them, but if you use a fully vented vinyl soffit, you the bugs don't go up there much and not if you have borate stabilized cellulose.

No way to cheaply measure air flow that I know of. Make sure the system is balanced and you will be fine.

Once you air seal and insulate, you somewhat reduce the necessity for venting (you don't eliminate it or even approach that, however, reducing the air leakage into the attic reduces moisture considerably).

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