Roofing Insulation is a very important part of the overall function of a flat roof system and is one of the 4 major cost of a flat roofing project.
Here is price guide for multiple thickness of Polyiso roof insulation in 2015. 
Tips on how to use this price guide
- Use only as a guide, check your local roofing supply house for exact pricing on roof insulation
- You can figure 1“ of roof insulation = an R value of 6 or R-6
- Check your local building codes for R value requirements in your area
- Two layers of roof insulation with staggered joints is preferable to one thick layer for example use two layer of 2” instead of one layer of 4” in your flat roof assemble
- Don’t forget to add between 5% - 10% waste to your project Depending on the size and shape
- Estimate the tapered roof insulation by the piece instead of by the Sq. ft. for more accurate take offs.
| ITEM | COST WITHOUT TAX | UNIT | QUANTITY | PRICE PER SQFT |
| Flat Stock ISO 1" | 12.46 | 4X8 | 32 SqFt | $0.39 |
| Flat Stock ISO 1 1/2" | 14.93 | 4X8 | 32 SqFt | $0.47 |
| Flat Stock ISO 2" | 19.93 | 4X8 | 32 SqFt | $0.62 |
| Flat Stock ISO 2 1/2" | 24.90 | 4X8 | 32 SqFt | $0.78 |
| Flat Stock ISO 3" | 29.90 | 4X8 | 32 SqFt | $0.93 |
| Flat Stock ISO 3 1/2" | 34.86 | 32 SqFt | $1.09 | |
| Flat Stock ISO 4" | 39.86 | 4X8 | 32 SqFt | $1.25 |
| Flat Stock ISO 4 1/2" | 44.83 | 32 SqFt | $1.40 | |
| Tapered ISO X | 11.08 | 4X4 | 16 SqFt | $0.69 |
| Tapered ISO Y | 16.21 | 4X4 | 16 SqFt | $1.01 |
| Tapered ISO Z | 24.32 | 4X4 | 16 SqFt | $1.52 |
To learn more about Polyiso roofing insulation download the guide below.
