Which project matches your space
Start with the surface and how you want to use the space. The project cards above cover attics, crawl spaces, basements, rim joists, walls, pole barns, garages, new construction and commercial buildings.
Open-cell and closed-cell are material choices within those projects. Compare their thermal and vapor behavior after the assembly, moisture conditions and available depth are understood.
How the main material choices differ
| Material | What it is suited for | What to watch |
|---|---|---|
| Open-cell foam | Air sealing and insulation where depth is available and a more vapor-open assembly fits the plan. | Usually needs more thickness than closed-cell for the same thermal target; moisture plan matters. |
| Closed-cell foam | Assemblies that benefit from higher thermal resistance per inch and less vapor permeance. | Not a waterproofing or structural fix; product and thickness decide suitability. |
| Fiberglass or cellulose | Common insulation alternatives that usually cost less than spray foam. | Air leakage and assembly continuity still affect performance, so insulation alone may not solve comfort issues. |
Insulation and air sealing are related but not the same job
Thermal resistance slows heat flow. Air sealing reduces leakage through gaps, seams, and penetrations. Foam can perform both in appropriate assemblies, which is one reason it is often specified.
Installation continuity still matters. Adjacent penetrations, ventilation, and unfinished transitions can undermine performance, so the written scope should describe the full assembly rather than only the foam area.
What to gather before you ask for quotes
- Which space or spaces you want addressed, and how each one is used.
- Access conditionsopen framing, finished surfaces, low clearance, crawl access, or occupied areas.
- Any known water, dampness, pest, or roof condition issues that could affect the assembly.
- Approximate surfaces or dimensions if you know them, and photos if they help explain access.
- Any deadline, inspection, or occupancy constraint that affects scheduling.
A FEW MORE ANSWERS
Questions before you get started
Do I need to choose open-cell or closed-cell before requesting a quote?
No, but the material choice affects thickness, moisture behavior, and price. A useful quote names the proposed foam product and explains why it fits the assembly.
Is spray foam the same as air sealing?
Not exactly. Insulation slows heat flow; air sealing reduces leakage. Foam can do both in the right assembly, but continuity and ventilation still need review.
Where should I start if I have several spaces?
List each space separately and describe how it is used. That helps the estimator compare options instead of pricing one vague whole-house number.