# Insulation cost review — September 15, 2026

## Current project allowance

- 2-inch roofing-grade polyiso; exact product and facer pending. Foil facing is not mandatory. No EPS substitution.
- 32 sheets per cabin; 192 sheets for six cabins. 4 x 8 feet each; includes the existing cutting allowance.
- $35/sheet working allowance: $1,120/cabin, $6,720 total before tax and freight.
- Lower sensitivity: $32.81/sheet published benchmark. Higher sensitivity: $45/sheet planning reserve. These are not delivered quotes.

## Evidence and limits

[Lakefront Supply, Chicago](https://lakefrontsupply.com/2-poly-iso-roof-insulation-board-flat-20-r-value-11-4-psi-4x8.html) lists GAF 2-inch 4x8 roofing polyiso at $32.81, with reinforced cellulosic facers, R-11.4 and 20 psi. Stock indicators conflict; confirm availability and delivery to Hagar Township. The listing describes conventional membrane roofs, not approval of our exact roof assembly.

[GAF product data](https://www.gaf.com/en-us/roofing-materials/commercial-roofing-materials/insulation/energyguard-polyiso-insulation) describes roofing polyiso in 20/25 psi grades. Confirm the needed bearing strength, fastening, moisture/exposure requirements and compatibility beneath flat purlins over retained shingles. The published compressive strength is not an allowable structural bearing load.

The previous $51.45/sheet allowance came from a specific [IKO foil-faced board at Hancock Lumber](https://shop.hancocklumber.com/product/polyiso-2-4x8-r13-0-foiled-faced-3400020). That historical benchmark has been superseded; foil facing was not established as necessary. The former rejection of non-foil roofing polyiso is withdrawn.

## Budget impact

Insulation decreases from $9,878.40 to $6,720: $3,158.40 material savings.
Other materials decrease from $24,116.64 to $20,958.24.
At the unchanged $4/LF steel purchasing target, materials total $29,220.24 and the full six-cabin cash budget totals $46,253.28 (about $7,709/cabin). Tax and review/permit allowances are excluded at owner direction. The 15% contingency is recalculated; freight and all other allowances remain unchanged.
At the $5.06/LF steel reserve basis, the program totals $48,771.12 (about $8,128/cabin).

These budgets exclude unpaid owner labor and do not explicitly price full repainting, new screen doors/lights or deck improvements shown in the renders. No supplier has been contacted and no bulk discount is assumed.

Budget instruction: owner states no permit is required. Combined review/permit allowance removed; tax excluded assuming out-of-state purchasing. Tax exclusion is a budgeting assumption, not a tax-exemption determination.