Open Cell Spray Foam in Knoxville, Tennessee

Open cell expands hard on application and reaches into every corner of a cavity. It covers far more area per dollar than closed cell and it is the better choice for sound.

Get a Free Estimate Call (865) 270-5126

Bringing the Ductwork Inside

Look at the photograph at the top of this page. The foam runs along the roof deck and down the gable walls, and the flex duct and air handler sit inside that line. That is the single most valuable thing open cell does in a Knoxville house.

A conventional vented attic here can pass 130°F on an August afternoon, and most homes run their ducts and air handler straight through it. The air conditioning is then pushing cooled air through tubes sitting in an oven, losing capacity the whole way. Insulating at the roof deck brings all of that equipment inside the conditioned envelope. Open cell is usually the economical way to do it, because a roof deck gives you the depth to carry a lower-density product.

Sound, Honestly Described

The open cell structure that makes this foam vapour-open also makes it absorb airborne sound noticeably better than closed cell at the same thickness. In an interior partition, around a media room, between a shared wall and a bedroom, or in a home office, it makes a real difference.

It will not make a wall soundproof. Sound control is a property of the whole assembly — mass, decoupling and sealing all matter more than the cavity fill. Foam is one part of it, and anyone promising silence from insulation alone is overselling.

Where We Will Not Use It

Open cell absorbs and holds water. Below grade, in a crawl space, against a foundation wall, or anywhere the foam might meet bulk water, we specify closed cell instead, even though it costs more. We would rather lose the cheaper line on the quote than install something that fails in a wet spring.

Talk through your assembly: call (865) 270-5126 or request a free estimate.

How a roof-deck job runs

Converting a vented attic

We get into the attic
We check what actually runs through it, how the roof is ventilated now, and whether anything up there is dumping moisture into the space.
The venting strategy changes
Sealing at the roof deck converts a vented attic to an unvented one. That is a design decision with consequences, and we set it out before any foam is ordered.
Old material out where needed
Loose fill on the attic floor usually comes out when we move the insulation line up to the deck, so it cannot trap moisture against the new work.
Apply, then verify depth
Foam goes on to the quoted depth across the whole deck, and it is checked away from the hatch, where it is easy to look good and easy to be thin.

Open cell questions

What people ask before choosing it

Is open cell the cheap option?

It covers more area per dollar, which is not the same thing. It gives a lower R-value per inch than closed cell, so it needs more depth for the same number. Where the depth exists, that trade is usually worth making.

Will sealing my roof deck cause moisture problems?

It changes how the roof assembly dries, which is exactly why it is a design decision rather than a default. We look at the existing ventilation and the whole assembly before recommending it. Done properly it is a well-established approach; done carelessly it is not.

Does open cell sag over time?

Cured foam adheres to the substrate and stays where it was applied; it does not settle the way loose fill can. Open cell stays soft and spongy to the touch, which is normal and not a sign of failure.

My upstairs rooms are unbearable in summer. Will this fix it?

If the cause is the roof assembly plus ducts running through a very hot attic, this is the direct fix and the difference is usually immediately noticeable. We will tell you on the inspection whether that is actually your problem, because sometimes it is not.

Can I use open cell in the crawl space to save money?

No, and we will not install it there. It absorbs water. Closed cell is the only foam we put below grade in this climate.