A 28 by 73 foot metal building in Blair County, Pennsylvania, 17 feet to the eave with a 4/12 gable roof. Walls, gables and roof deck sprayed at 2 inches of closed-cell foam, 4,724 square feet at R-14.8.
Scope
| Surface | Area | Closed-cell thickness | Est. R-value |
|---|---|---|---|
| Walls | 2,936 ft² | 2" | R-14.8 |
| Gables | 131 ft² | 2" | R-14.8 |
| Roof deck | 2,155 ft² | 2" | R-14.8 |
| Total treated | 4,724 ft² | 2" | R-14.8 |
Why two inches on the whole envelope
This is a storage and work building, not conditioned living space, so the goal was to stop the roof from sweating, keep the winter chill off the panels and make the building heatable when someone is working in it. Two inches of closed-cell does all three: it is an air barrier at one inch and a vapor retarder at about two, and the hot-box data shows 86% of the achievable heat-loss reduction is captured by the second inch. Going to three would have added roughly a third to the price for two more percentage points. Doors and overhead openings, 498 square feet, were subtracted before pricing.
R-values are nominal manufacturer values (aged, ASTM C518) as quoted on the data sheet, not a guarantee of energy savings. Customer names withheld.