How thick does closed cell spray foam need to be?

It depends on the assembly and the code requirement for your township. Two inches gets you around R-13 and full vapor-retarder performance; 3 inches in a 2x4 wall reaches roughly R-21. We confirm the target thickness on site before quoting.

Is closed cell foam worth the extra cost over open cell?

In basements, crawl spaces, rim joists and any assembly touching moisture — yes. It gives you insulation, air sealing and vapor control in one product. For interior walls and attic slopes above grade, open cell is often the better value.

Can closed cell foam be sprayed over existing insulation?

No. Spray foam has to bond to a clean substrate. Old batts or damaged fiberglass are removed first so the foam adheres properly and reaches its rated performance.

How long before we can re-occupy the space?

Closed cell foam is tack-free within minutes and fully cured in about 24 hours. We typically ask that the work area stay vacant for 24 hours with ventilation running.

Does it need a thermal barrier over it?

In living spaces, yes — code requires a 15-minute thermal barrier such as half-inch drywall. In unfinished attics and crawl spaces an approved ignition barrier coating like DC 315 can be used instead, which we also apply.

Do you serve my area?

We cover New Jersey, New York and Connecticut from our base in Hillside, NJ. Mention your address when you request an estimate and we'll confirm scheduling.

Closed Cell Spray Foam Insulation | Tri State Spray Foam

Overview

What closed cell spray foam insulation actually does

Closed cell spray foam is the highest-performing insulation we install. It cures into a rigid, dense material that delivers roughly R-7 per inch, seals air leaks, and acts as its own vapor retarder — so a single application handles insulation, air sealing and moisture control at once. Because the cells are sealed, water cannot pass through it, which makes closed cell the right choice for basements, crawl spaces, rim joists, foundation walls, metal buildings and any assembly exposed to bulk water or high humidity. It also adds meaningful racking strength to a wall assembly, a benefit no batt product can offer.

What's Included

Every project covers these points

R-6.5 to R-7 per inch — the highest R-value per inch available
Class II vapor retarder at 1.5 inches and above
Seals every gap, seam and penetration in the assembly
Rejects bulk water — will not absorb, rot or support mold growth
Adds racking and shear strength to walls and roof decks
Ideal for basements, crawl spaces, rim joists and metal buildings

Our Process

Four steps from first call to walkthrough

01

On-Site Assessment

We inspect the cavity depth, existing insulation, moisture conditions and ventilation before quoting anything.

02

Prep & Masking

Windows, floors, mechanicals and finished surfaces are masked off, and the work area is ventilated for the application.

03

Spray Application

Foam is applied in controlled lifts to the specified thickness so it cures evenly and reaches full rated R-value.

04

Trim & Walkthrough

Excess foam is trimmed flush to framing, the site is cleaned, and we walk the job with you before we leave.

Why It Matters

What you actually get from doing this properly

The difference between an insulation job that works and one that disappoints comes down to a handful of specifics. Here are the ones that matter for this service.

01

Highest R-Value Per Inch

Roughly R-7 per inch means full thermal performance even in shallow 2x4 cavities and tight rim joists.

02

Built-In Vapor Control

At 1.5 inches and up it acts as its own vapor retarder — no separate poly barrier needed.

03

Water Will Not Pass

Sealed cells reject bulk water, so basements and crawl spaces stay dry and mold-resistant.

04

Structural Gain

Rigid foam bonds to framing and sheathing, measurably stiffening the wall assembly.

Our Standard

Disciplined habits, not shortcuts

Spray foam is unforgiving — you get one pass to get it right, and mistakes are permanent. These are the standards we hold ourselves to on every job.

Clear Communication

Straightforward answers and a written scope, so you know what you're buying before we start.

Proper Preparation

Masking, containment and ventilation are set up before the first pass is sprayed.

Correct Specification

Product and thickness chosen for the assembly and the code requirement, not for convenience.

Respect For Property

Floors, windows, mechanicals and finished surfaces protected throughout — overspray is permanent.

Final Verification

Coverage checked, thickness confirmed, site cleaned, and a walkthrough before we leave.

FAQ

Closed Cell Spray Foam Insulation — questions, answered

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Ready When You Are

Get a free estimate for closed cell spray foam insulation

Tell us about the space. We'll look at it, spec it honestly, and give you a written estimate with no pressure attached.

(347) 314-5335

Closed Cell Spray Foam Insulation