Open cell and closed cell spray foam insulation for the home are both effective solutions — one or the other may work better in different climates and parts of the home.
Open Cell and Closed Cell: Similarities and Differences
Both spray foam types:
- Spray in to fill all gaps and holes
- Form an air barrier to stop drafts and air leakage
- Don't provide a food source for mold (check with your spray foam manufacturer)
- Don't provide a food source for pests
Here are some differences:
- "Breathes" — it is vapor permeable and this can let your home dry out.
- Moderate cost $$ per square foot
- Reduces sound transmission so you don’t hear from one room to the next
- Flexible – moves with your house to ensure there are no gaps in your insulation and no loss of air seal
- Doesn’t absorb water; lets it drain down through the insulation (check with your spray foam manufacturer)
- Good thermal insulation - R-3.7 per inch thickness
- A 3.5 inch thickness is suggested to get an air barrier
- Doesn’t “Breathe” – acts as a vapor retarder
- Higher cost $$$ per square foot in most applications
- Lower sound reduction
- Stays rigid – helps wall strength; impact resistant.
- Doesn’t let water in (check with your spray foam manufacturer) – this is an advantage in flood zones. Great for flood prone areas
- Great thermal insulation – R-6.0 per inch thickness
Where to use open cell and closed cell spray foam in your home
Which climate zone are you in?
Check the map at the bottom of the page.
Roof, attic, exterior walls, bonus room:
- Open cell (+vapor retarder on the warm side) is a lower-cost alternative where the wall is thick enough to reach your insulation requirements.
- Closed cell may be preferred in very cold areas (zone 6 and above) because of its higher R-value. It doesn't require a vapor retarder.
- Open cell is a lower-cost alternative for basements in cold climates
- Closed cell is preferable in parts of your home that are vulnerable to flooding
Roof, attic, exterior walls:
- Open cell should be used in new homes and additions as it allows the new home to dry out, protecting against mold growth. It allows for the drying of the building envelope to the interior of the building. It's also generally a lower-cost alternative in retrofits.
Basement and flooring above unconditioned spaces:
- Open cell with a vapor retarder paint, or closed cell, can be used under raised floors to protect hardwood from cupping due to outdoor moisture. It is also effective for basements above the water table.
- Closed cell is preferable in parts of your home that are vulnerable to flooding.