A Radiant Barrier Belongs in the Reroof Quote, Not After It

A radiant barrier is a thin reflective layer, usually aluminum foil on a paper or plastic backing, that faces an open air space in the attic. If your roof is being replaced, the attic gets a closer look than usual, so the time to decide on a barrier is while the roof quotes are still being compared. The question tends to come up late, after the bid is signed and the attic has already been cleared, and by then the work has to be added to a job that was written without it.

What it does and what it does not do

A radiant barrier reduces heat moving across an air gap by radiation. Heat from a hot roof deck on a July afternoon travels as radiant energy, and a reflective face sends much of that energy back instead of letting the attic absorb it. The effect is strongest in summer. Attic temperatures can climb well above the outdoor air on a sunny afternoon in St. Charles, and a barrier can take some of that load off the rooms below.

It does not do everything. A barrier does little against heat that moves through solid materials by conduction, so it cannot replace attic insulation. It also does not fix ventilation. Air still needs a path from the soffit to the ridge to carry moisture and heat out. In winter the bigger issue is warm air leaking from the living space into the attic, which heats the roof deck and feeds ice at the eave. A barrier does little to stop that leak, so if the house has ice damming, air sealing and insulation belong in the discussion before any reflective layer does.

Where it goes in a St. Charles attic

A barrier is usually installed from inside the attic. The installer staples the reflective product to the underside of the rafters, or to the bottom chords of trusses, with the reflective face toward an air space beneath the roof deck. Trusses are common in newer subdivisions, and a truss attic usually has less room to work than a stick-framed one, so the installer needs boards laid across the bottom chords and a clear route from the access hatch to the far corners.

Two things defeat a barrier. The first is insulation laid directly on top of it, because the reflective face then faces fiberglass or cellulose instead of air. The second is dust. A foil face that collects dust and attic debris reflects less heat than a clean one. An installer who lays a barrier over flattened insulation, without raising the insulation or leaving a gap, has not done the job the product was made for.

The roof crew has little to do with this part. The barrier does not need to go up during tear-off, and it can be installed after the new shingles are on. What it needs is access, a cleared attic floor, and someone whose job includes the attic. That is why it should be a named line in the quote rather than a favor added at the end.

Why it belongs in the quote

A reroof quote is a list of work on a roof that is open or about to be. The attic is part of that work whenever the roof comes off, because the crew will look at the decking, check the rafters for water staining, and review the ventilation. A barrier is one more item on that list. If it is left out, the homeowner may pay for a second visit or a second crew, and the attic may already have been cleaned, cleared and closed.

Price is not the only reason to ask. A barrier changes what the attic needs, and a quote that does not mention it assumes the attic will be left as it was. Keys Roofing puts a written scope with photos and measurements in the homeowner's hands, so the barrier, its square footage and the attic clean-up should appear in that scope in plain terms.

Questions to ask the roofer

Ask these before you sign, and write the answers next to the line in the scope.

• What product is being installed, and which face is meant to point toward the air space?
• Is the barrier stapled to the rafters or truss bottom chords, with a gap between it and the insulation?
• Is any insulation being removed, raised or moved to make room for it, and is that work priced?
• How many square feet of attic floor and rafter bottom will be covered, and does that match the attic measurements in the scope?
• Who clears the attic floor of stored boxes, and who removes the debris the installer makes?
• Will there be photos of the installed barrier before the access hatch is closed?
• If the house has ice damming at the eaves, what air sealing is included, and is it listed separately from the barrier?

What to decide now

The decision is simpler than the product literature makes it sound. Decide whether summer heat in the upstairs rooms is a problem you want fixed, check whether the attic has the ventilation and air sealing it needs, and then either ask for the barrier as a line item or leave it off on purpose. The one outcome to avoid is discovering the question after the attic is closed.

If you want someone to look at the attic before you choose, Keys Roofing can be reached at (314) 220-2333. Ask for the attic to be part of the walk, and ask for the barrier question to be written into the scope with the rest of the work.