Vapor Seal® Boxes: Passes code. No caulk. No foam. No gaskets.

If you've ever stood in front of an exterior wall rough-in and wished you could just nail it and walk away — you're not alone.

That's the headache we're solving today and...

Building codes about air leakage keep getting tighter.

Enter Allied Moulded Vapor Seal® boxes. They're nonmetallic, air-sealed, and designed specifically for exterior walls and ceiling assemblies. Nail them up. Wire them up. Done.

No caulking. No foam. No gaskets. No coming back because someone else damaged your box seal.

The code thing — because you have to think about it

The International Energy Conservation Code (IECC) cares about air leakage. A lot. Every penetration through an exterior wall or ceiling is a potential leak. Electrical boxes are penetrations.

Vapor Seal® boxes exceed NEMA OS4 air leakage standards. That's the official way of saying: this box seals itself.

You don't have to explain it to the inspector. You don't have to add sealant. You just install it and move on.

The flexible flange nobody else has

The flange is flexible silicone. That matters more than you'd think.

Other trades will damage your boxes. Drywallers. Insulators. Guys carrying sheet goods. A rigid flange cracks or bends permanently. Then your seal is compromised.

The Vapor Seal® flange gives. Then goes back. The seal stays intact.

Available in two versions: "V" for single drywall, "V2" for double 5/8" drywall. You'll see it on the box.

PVC vs fiberglass — here's the difference

PVC (flexBOX®)Fiberglass (fiberglassBOX™)Best for Standard residential new construction Multi-family, fire-rated assemblies, commercial Back-to-back?Yes — only Allied Fiberglass has this Fire rating. Putty pads? Not needed (even in fire-rated walls) Installation Self-sealing elastomeric clampsSpeed Klamps™, no-tool knockouts. All boxes carry a standard 2 hour fire UL rating.

The big story: fiberglass boxes can go back-to-back in 2x6 fire-rated walls. Nobody else does this. It saves a ridiculous amount of labor because you don't need putty pads. And you don't have to offset boxes.

What we stock at CPESI

PVC flexBOX® (standard residential)

• Single gang (P-221NV)

• Two gang (P-442NV)

• 4" round fixture support (PC234 series — with ground strap, bar hanger options)

Fiberglass (multi-family, fire-rated)

• Single gang through four gang switch/receptacle boxes

• Range/dryer box (RD-42V)

• Back-to-back rated for 2x6 fire-rated walls

• Ceiling and fan-rated boxes (9350-FANVB with bar hanger)

All of it is UL listed. All of it meets NEC Article 334. All of it is in stock in Denver.

The short version

Nail it. Wire it. Forget it. Code passed.

Stop by any CPESI location or call. We'll get you the right Vapor Seal® box for the job — PVC or fiberglass, 1 to 5 gangs, ceiling or wall.