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Johns Manville Ventsulation Felt Venting Base Sheet, Black, 36 in. x 36 ft. Roll
Regular price $91.00Orders start at $399 — combine any items to reach the minimum. Learn more
Johns Manville Ventsulation Felt Venting Base Sheet, Black, 36 in. x 36 ft. Roll
Johns Manville Ventsulation Felt is a venting base sheet for built-up and modified bitumen roofing systems installed over substrates that may contain moisture. Its 1 in. embossed waffle grid channels moisture vapor and helps prevent blistering. This listing is one Black 36 in. x 36 ft. roll, mineral-surfaced on one side.
Key Features:
- Vents moisture vapor: The 1 in. embossed waffle pattern grid channels promote moisture vapor venting.
- Prevents blistering: Helps prevent blistering of asphalt-based roofs over potential moisture-containing substrates.
- Ideal for re-covers: Suited to re-covers over existing roof membranes and lightweight insulating substrates.
- Dimensionally stable: Low moisture content and excellent dimensional stability make it an ideal replacement for organic base sheets.
- Rot resistant: Resistance to rot supports long service life under the roofing system.
- Mineral surfaced: Surfaced with coarse minerals on one side for a solid, stable substrate.
Specifications Table:
| Specification | Details |
|---|---|
| Brand | Johns Manville |
| Sell unit | 1 roll, 36 in. x 36 ft. |
| Product line | JM Ventsulation base sheets |
| Material | Roofing felt with embossed waffle pattern |
| Color / finish | Black, coarse mineral surfacing on one side |
| Dimensions | 36 in. x 36 ft. per roll |
| Nominal size | 36 in. x 36 ft. |
| Feature | 1 in. embossed waffle pattern grid channels |
| Intended use | Venting base sheet for BUR and modified bitumen systems |
| Approved applications | Re-covers over existing roof membranes, lightweight insulating substrates with potential moisture |
Coverage & How Much You Need:
Each roll measures 36 in. wide by 36 ft. long, covering 108 sq. ft. before laps. Install with the specified head and side laps and fastening pattern for the base sheet, so a single roll nets less than its full square footage.
Fit and Compatibility:
Used as the base sheet beneath any Johns Manville built-up or modified bitumen roofing system over potentially moisture-containing substrates such as re-covers over existing membranes and lightweight insulating fill. Membrane plys, adhesives and fasteners are installed over it and sold separately.
Frequently Asked Questions (FAQ):
Q: What is included?
A: One Black Ventsulation Felt roll measuring 36 in. x 36 ft., mineral-surfaced on one side.
Q: How much does one roll cover?
A: A roll covers 108 sq. ft. before laps; deduct lap and fastening requirements when estimating.
Q: When should I use a venting base sheet?
A: Use it when roofing over substrates that potentially contain moisture, such as re-covers over existing membranes or lightweight insulating fill, where blistering is a risk.
Q: How does the waffle pattern work?
A: The 1 in. embossed waffle grid channels allow moisture vapor to vent, helping prevent blistering of asphalt-based roofs.
Q: What systems can it go under?
A: It serves as a base sheet for any built-up roofing or modified bitumen roofing system.
Q: Can it replace organic base sheets?
A: Yes, its low moisture, dimensional stability and rot resistance make it an ideal replacement for organic base sheets.
Expert Verdict — Reviewed by the SuperArbor Pro Desk
Reach for Ventsulation Felt when a re-cover over an existing asphalt roof or moisture-prone lightweight insulating substrate risks blistering; the waffle channels relieve vapor pressure that would otherwise lift the new membrane. Fasten and lap the base sheet per JM's specifications before mopping or torching plies. It is not a finished roof layer, so always cap it with a full BUR or modified bitumen system.
Follow safe roofing practices including fall protection and safe handling of hot asphalt, torches or adhesives used over the base sheet.
Order Johns Manville Ventsulation Felt today to protect your re-roof from moisture blistering.
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