Should I spray foam my attic?
Daniel Lopez
Updated on March 14, 2026
That's because open-cell spray foam can transmit air and moisture. Closed-cell spray foam is a better choice for keeping subfloor moisture at optimal levels, while open-cell spray foam is a better choice for walls and attics, because it allows homes to “breathe,” Yates said.
Why you shouldn't spray foam your attic?
It Should Only Be Installed by ProfessionalsIt cures with an exothermic reaction that generates a lot of heat, and if you put it on too thick, it can cause fires.
Is spray foam in the attic worth it?
A properly done spray foam job not only insulates but also greatly reduces the air leakage of a home. But that only works if the installer can get it into the places where most of the air leakage happens. In an attic, the eaves are one of the most critical places to get good coverage with the foam.Do you spray foam attic floor?
One technique that can both increase attic insulation and air seal the attic is to apply a layer of spray foam to the attic floor, then to install additional blown-in or batt insulation to meet or exceed insulation R-value requirements.Where should you not use spray foam insulation?
When NOT to Use Spray Foam Insulation
- For areas that are too close to electrical boxes:
- For areas too close to ceiling light boxes:
- Open-cell spray foam on your roof:
- For closed-cavity spaces:
- If you have a history of skin, respiratory, or asthma problems:
Spray foam attic insulation | BEFORE AND AFTER
What is the best way to insulate an attic?
You can use rigid foam panels or do as Tom Silva does with nearly all houses these days: Hire a pro to install spray foam insulation. Foam blocks airflow needs no vapor barrier and has a higher R-value per inch than loose fill or batts, so you'll get more protection with less depth.What is the downside to foam insulation?
On the downside, spray foam insulation comes at a price that is considerably more expensive than fiberglass. Often times, spray foam is triple the price of fiberglass and sometimes it can be more. Applying spray foam insulation is also something that is not advised to do by yourself unless it is a very small job.What are the downsides of spray foam insulation?
List of the Cons of Spray Foam Insulation
- Spray foam insulation does not always fill every possible cavity. ...
- Spray foam insulation might encourage water damage for some homeowners. ...
- Spray foam insulation can sometimes shrink. ...
- Spray foam insulation requires a lot of experience to get it right.
Does spray foam devalue your house?
In fact, according to Heritage House, they have seen entire roofs rotted and unrecoverable after SPF has been used. They state that by using SPF in your roof, '…you will devalue your home by the amount that a new roof will cost, and more. ' And we agree.Can spray foam rot your roof?
Studies show that open-cell spray foam is risky in colder climates. Indoor moisture diffuses through the foam and comes in contact with the cold roof sheathing. The spray foam traps the moisture against the roof, which results in eventual decay.Is spray foam insulation Safe 2021?
After proper curing, spray foam insulation is safe and should not cause any health-related or even structural problems in your property. However, it is highly important for you to call a licensed insulation contractor to install this type of insulation in your property.Should I insulate the rafters in my attic?
Insulating between rafters will do no good, because the attic should be ventilated, and the rafter insulation would be between two unheated spaces. You can add insulation to the floor; the more the merrier. Just don't put it in the eaves. Also, make sure the attic is well ventilated.Is spray foam insulation worth the extra money?
If you see the benefit of insulating your new construction home correctly from the start for long-term comfort, energy savings month after month, and fewer headaches while you live in the house, then spray foam insulation may very well be worth the extra cost to you.Is spray foam better than insulation?
When compared with other insulation products, spray foam insulation offers the highest R-Value per installed inch. Because spray foam will completely seal and insulate the “building envelope”,, allowing for the ultimate in thermal protection (and R-Value). Spray foam can be closed-cell or open-cell.Does spray foam cause mold?
Foam building insulation, in both spray foam and foam board products, is resistant to mold growth but as we will explain here it is not absolutely mold-roof, and on occasion we do find mold growth on the surface of even closed-cell foam, in open-celled foam (rare), and on th surface of EPS and other foam insulating ...How long will spray foam last?
With proper application, Spray Foam will last the lifetime of your home. Even roofing applications will last upwards of 30 years, with proper long-term maintenance. Spray Foam insulation adheres extremely well to virtually all substrates, and maintains its rigidity once dry.Does spray foam create moisture problems?
While the benefits of spray foam are multifaceted—it can reduce energy costs, increase a home's structural integrity, create a moisture barrier and prolong the life of an air conditioning unit—it can also cause problems.Is it worth it to insulate attic?
Installing attic insulation this winter is a worthwhile long-term investment because it can significantly decrease your heating bills. As an added benefit, when the hot D.C. temperatures come back, the attic insulation will also minimize your air conditioning bills.Can you have too much insulation in your attic?
It's possible to over-insulate an attic as too much will cause moisture buildup and eventually result in mold. Eventually, adding more insulation leads to diminishing returns in trapping heat as well.Is spray foam insulation better than fiberglass?
Spray foam insulation has a higher R-value than fiberglass, making it a better insulator. Another difference between them is that spray foam is watertight while fiberglass cracks under moisture. However, installing spray foam requires a professional while fiberglass is easy to install yourself.Does a spray foam roof need to be vented?
By using an air-impermeable insulation, like spray foam, on the roof deck will stop any air movement. If the home's building envelope is completely air sealed, then the air traveling up to the attic won't be unbearably hot, and there will be no need to cycle it out with vents.How long will insulation foam last?
Typical Insulation LifespanThe International Association of Certified Home Inspectors states that spray foam insulation, wrap tape and housewrap insulation can last for more than 80 years. At the same time, cellulose, loose-fill, foamboard, loose fill and rock wool insulation can last up to 100 years.