What are your thoughts of closed cell in the attic. There are many pro’s and con’s on this method. What I’m seeing is this. Closed cell between the rafters and walls. An attic fan installed. No other circulation in the attic. If the fan turns on, it’s going to pull air from the home around slight gap around the pull down staircase.
On the air handler there looks to be mold growth. I believe the humid air from the home may be getting pulled into the attic.
That are your thoughts?
Thanks,
Exhaust fan to the exterior or a fresh air intake?
Where are you located?
Cold Northern State?
Hot Southern State?
Temperate area?
Humid or Arid region?
So many questions…
Was the mold growth or the foam there first?
It goes out to the exterior
Long island NY, it does bet very humid since the home is close to the ocean.
That I don’t know. I just did the inspection today.
Actually, it looks like there is mold on a blob of insulation. I would call it out and let them figure out the rest.
yep, found it on several areas of the insulation.
When you move the thermal envelope to the roof deck and the attic side walls, then the attic becomes interior space and should be treated as such. That means a supply and a return system, just like any other room inside the home.
I agree with Ryan. The air in the attic space should be conditioned the same as the house. If they only have a fan exhausting to the exterior, they’re creating a low pressure in the attic that will pull moisture in from the house.
Probably around that window as well
Are you sure it’s closed cell? Kinda looks like open cell but hard to tell from the picture. Open cell is softer than closed cell.
I would probably recommend checking temperature and humidity levels.
I so agree. That’s what I told the client today.
I have both closed cell and open cell in my house. Checking what they put up was closed cell.
Yes! All those questions matter. And local fire codes on the foam… there should be some coatings or a layer of drywall…
Dr. Joe at https://buildingscience.com/ has been speaking about this for years (decades?). The 2018 IRC finally addressed it the Florida Building Code finally caught up to the problem in the 2020 Code. Some form of ventilation is needed. Diffusion vents, or other ventilation. There are many other threads addressing this issue on this MB BTW the search function on this MB has been less reliable for me than using internet search engines… like “NACHI forum spray foam insulation”.
Whenever an attic is encapsulated with closed-cell foam, the attic space becomes a part of the total conditioned space. The load on the A/C system increases by 50% or more in some cases, depending on the roof structure and design. Even though the closed-cell foam blocks most of the exterior heat and humidity, some degree of both will be realized. At the least, some additional supply and/or return vents should be installed into the HVAC trunk line or branch ducts inside the attic, to prevent hot or cold areas in the nooks and crannies of the higher structural points in the underbelly of the roof; as well as to remove the humidity. At worst, a smaller supplemental A/C system should be added to serve the attic. The bathroom, laundry room, and range vent hood should also be ventilated to the exterior to dispose of excess humidity.
Does the home have an ERV? Whole house dehumidification?
I don’t see a lot of rafter foam insulation, but I’ve researched it quite a lot after seeing it for the first time about 10-12 years ago. (I hadn’t even heard of this use and seeing it for the first time was a shock.)
It can be a great way to insulate an attic in new construction designed from the ground up for it. And it can be a disaster when adding it to an older house that was not designed for it, without doing some fundamental changes.
When they first added the foam to this older home, then adding AC for the attic might be the “worst” but today after some years, I suspect that “worst” could be really bad and expensive.
The A/C system serves as the best and most economical dehumidification system if sized and installed properly. The condensate water outflow even carries dust and contaminants with it, to help purify the air.
