Spray foam insulation

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bobbyburke

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My house is 2 stories, a square box, 1200 sq ft, built in the '40s with a hip roof.
I cut a hole in the 2nd-floor hallway ceiling to install attic stairs and noticed there was frost on the blown-in insulation.
We are near Chicago so it gets pretty cold some winters.
I realize the house is uber leaky being so old and it is generally in good condition otherwise.
We do run a whole house humidifier in the winter, don't currently have a bathroom exhaust fan (bathroom on the 2nd floor),
and don't have an exhausting range hood in the 1st-floor kitchen.

My intention is to ditch all the blown-in and have a spray foam contractor come to shoot the entire attic.
I then want to deck the ceiling joists so we can store stuff up there.
I wanted to put in an attic fan but there are many who discourage that.
Any thoughts or has anyone else done that around the midwest?
 
My house is 2 stories, a square box, 1200 sq ft, built in the '40s with a hip roof.
I cut a hole in the 2nd-floor hallway ceiling to install attic stairs and noticed there was frost on the blown-in insulation.
We are near Chicago so it gets pretty cold some winters.
I realize the house is uber leaky being so old and it is generally in good condition otherwise.
We do run a whole house humidifier in the winter, don't currently have a bathroom exhaust fan (bathroom on the 2nd floor),
and don't have an exhausting range hood in the 1st-floor kitchen.

My intention is to ditch all the blown-in and have a spray foam contractor come to shoot the entire attic.
I then want to deck the ceiling joists so we can store stuff up there.
I wanted to put in an attic fan but there are many who discourage that.
Any thoughts or has anyone else done that around the midwest spray foam insulation washington dc?
thanks in advance for any help or feedback
 
Are you looking to spray foam the underside of the roof deck and making your attic conditioned? Make sure you seal all the penetrations coming into your attic space from the living space. Any holes around plumbing or electrical cables should be sealed with foam. Your attic stairs should have an insulated cover and be weather stripped. I'd look to add an exhaust fan to both the bathroom and kitchen to get rid of that moisture as I'm fairly certain you don't open the window to vent out the humidity. If at all possible vent the kitchen exhaust fan to the outdoors. The filters that send it back into the air don't really do much other than trap some of the grease from the exhaust before spewing the smoke and combustion byproducts into the room.

With respect to the attic fans, I've heard good and bad on them, I tend to agree with the attitude they are a bad idea, especially if the attic isn't sealed well from the conditioned space below. They will suck conditioned air from the living space through all the nooks and crannies in the ceiling. If the ceiling is well sealed the air should all be pulled from the soffit or gable vents, but if the venting soffit/ridge is properly sized and not blocked it should have a decent flow by normal convection.

I'd like to insulate my roof deck as our upstairs HVAC system and all the ductwork for the second floor is in the attic.
 
Hello. I also need some suggestions from you. please bear with me. I'm buying a house that has unfortunately had spray foam insulation put into the loft. It's become apparent that this could be an issue for lending and so the vendors have agreed to have this removed. Is it likely this will cause damage to the roof/tiles itself? Am I mad to purchase the following removal?
Why is the bank requiring it to be removed? What type of roof do you have? If shingles, the spray foam is likely up against either OSB sheathing or plywood sheathing. Removing it would have no impact to the shingles. I see you're in the the UK, so your roof could be tiles, slates, shingles, thatch... I've seen roofs in the UK just use furring strips with no sheathing. If that's the case some of the spray foam could be attached to the underside of your tiles.
 
Dear Bobby: We previously owned a ~1950 Cape style house in Massachusetts, where the winters also get cold. Here are some suggestions:
  • Frost: This is caused by moisture migrating up into your attic - a common problem. If there are any penetrations in the attic floor, the 'stack effect' pulls warm, moist air up into the attic. In addition to frost in the winter this can lead to mold when temps increase -- and increases your HVAC costs. Most homeowners can fix this problem themselves.
  • First, find every penetration in the attic floor, e.g. recessed ceiling light cans, holes around pipes and wiring, a gap around a chimney, etc. Every gap must be sealed airtight.
  • Recessed ceiling lights can be covered with Tenmat covers, available from Home Depot and Lowes. You can also make boxes with drywall, and seal the corners with foil HVAC tape. (NOT silver fabric 'duck' tape.) Seal the bottom edges with fire barrier caulk - NOT canned spray foam like Great Stuff. Canned foam is extremely flammable after it cures and will ignite at just 250 degrees F - significantly less than the ignition temp for paper or wood. This includes versions with "Fire Block" on the label! So never install canned spray foam near any source of heat, e.g. celing lights and exhaust ducts. Use a fire resistant caulk, e.g. 3M FB 136,, available at Home Depot and Lowes.
  • Seal holes around exhaust vents, pipes and wiring: Anything hot, e.g. an exhaust duct, needs to be sealed with fire barrier caulk, e.g. 3M FB 136.; otherwise use Great Stuff or 3M canned spray foam. If the gap is > 1/8", first pack it with rock wool or a foam 'backer rod' (both available from Home Depot or Lowes) then cover that with fire barrier caulk (if hot) or canned spray foam.
  • Gaps around a chimney: Cut pieces of aluminum sheet to bridge the gaps, and seal the edges with fire barrier caulk.
Exhaust vents: As others noted, you should make every effort to run ducts to the exterior for your bath and kitchen fans. Use metal ducts or flexible metal ducting - NOT the flimsy silver plastic ducts.

HVAC ducts in the attic: If you have HVAC ducts in your attic, you are losing $$. The ducts should be insulated to R8+. Wrap the ducts with rock wool or fiberglass batts, and seal the joints and edges with foil HVAC tape (again, NOT silver fabric 'duck' tape).

Plus, if you have HVAC ducts in your attic, create a "T" on one of the 'return' ducts and run an extension up to the peak of your attic. After the foam is sprayed, your attic will become sealed 'conditioned space' - and the new return duct will help to reduce moisture.

Foam insulation: First, the spray foam MUST be >3" of CLOSED cell, to avoid condensation on the roof deck and gable end walls - which will lead to rot. 'Open' cell foam does not provide a moisture barrier. We sprayed 8" of foam under the roof deck of our home and immediately noticed the difference in the house, both in comfort and our heating bill. As the foam is sprayed, it will cover the rafters and gable end studs, making it difficult to measure the actual depth of the foam. So screw pieces of wood to the rafters and studs, showing the target depth.

If you are concerned about Global Warming, you should also pick a spray closed cell foam that uses a low GWP blowing agent - which are also much less toxic. For example: Heatlok HFP See: HEATLOK HFO HIGH LIFT | Huntsman Building Solutions

This is linked to another issue. Foam is flammable, emits toxic smoke when it burns, and MUST be covered by a thermal barrier in any attic that is used for storage. You have two options: (1) Install 1/2" drywall over the foam, or (2) spray a generous coat of intumescent paint on the foam. For example: Fireguard E-84, available from Home Depot. If you want to install drywall, screw a bunch of 8" long pieces of 2x4 on the rafters and gable end wall studs. This will provide measurement for the depth of the foam, and mounting points for the drywall. (This is what I did in our current house - also built around 1950.)

Attic fan: As noted above, your attic will become sealed 'conditioned space' after foam is installed. All vents into / out of the attic should be blocked and sealed. This is significantly more efficient. There is zero need for an attic fan - which would eliminate the benefits of your upgrade project.

I hope this is helpful. Let me know if you have any questions.
 

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