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Kingspan GreenGuard Q250 1/4 in. x 4 ft x 48 ft Fanfold Siding Underlayment, White
Regular price $59.88Orders start at $399 — combine any items to reach the minimum. Learn more
Kingspan GreenGuard Q250 1/4 in. x 4 ft x 48 ft Fanfold Siding Underlayment, White
Kingspan GreenGuard Q250 is the most economical fanfold siding underlayment in the GreenGuard line: a 0.2 in. extruded polystyrene foam board with high-impact polystyrene facers on both sides. Each 4 ft x 48 ft fanfold board covers about 192 square feet and provides a smooth, level nailing surface for new siding. Perforations allow moisture vapor to escape.
Key Features:
- Economical insulation: The most economical fanfold siding underlayment in the GreenGuard line.
- Durable XPS core: 0.2 in. extruded polystyrene foam core with high-impact polystyrene facers on both sides for durability.
- Vapor permeable: Perforated to allow moisture vapor to escape from the wall assembly.
- Smooth nailing base: Provides a smooth, level nailing surface for new siding.
- Easy to handle: Lightweight, durable, and cuts clean and easy.
- Fanfold format: 4 ft x 48 ft fanfold board unfolds quickly along the wall.
Specifications Table:
| Specification | Details |
|---|---|
| Brand | Kingspan |
| Sell unit | 1 board, 1/4 in. x 4 ft x 48 ft |
| Product line | GreenGuard Q250 |
| Material | Extruded polystyrene foam (XPS) core with high-impact polystyrene facers |
| Color / finish | White |
| Thickness | 1/4 in. (0.2 in.) |
| Dimensions | 1/4 in. x 4 ft x 48 ft |
| Coverage per unit | Approximately 192 sq ft per board |
| Finish / texture | Perforated fanfold |
| Intended use | Fanfold underlayment beneath new siding |
Coverage & How Much You Need:
One 4 ft x 48 ft board unfolds to cover roughly 192 square feet of wall area. Measure the wall square footage and divide by 192, adding a little for laps and cut waste around windows and doors.
Fit and Compatibility:
Install under vinyl, wood, fiber cement or composite siding as a leveling and nailing base. Siding, starter strips and fasteners are sold separately.
Frequently Asked Questions (FAQ):
Q: What is included?
A: One 1/4 in. x 4 ft x 48 ft white fanfold underlayment board, sold per board.
Q: How much does one board cover?
A: A 4 ft x 48 ft fanfold board covers approximately 192 square feet before cut waste.
Q: Is it perforated?
A: Yes, Q250 is perforated to allow moisture vapor to escape.
Q: Why use fanfold underlayment?
A: It provides a smooth, level nailing surface for new siding over existing walls.
Q: How thick is it?
A: 0.2 in., commonly called 1/4 in.
Expert Verdict — Reviewed by the SuperArbor Pro Desk
Fanfold underlayment is the fast, economical way to flatten an existing wall before residing: butt boards tightly, stagger vertical joints and fasten on the stud line per the siding manufacturer's requirements. The perforations help the wall dry, so do not substitute a non-perforated board where vapor escape matters. On badly bowed walls, consider a thicker fanfold grade instead of the 1/4 in. Q250.
Wear eye protection and cut with a sharp utility knife on a flat surface, keeping hands clear of the blade.
Get Kingspan GreenGuard Q250 fanfold underlayment now for a smooth, level base under your new siding.
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