1. What is roofing underlayment?
  2. How do I know which underlayment to use?
  3. How long can NEI® AC underlayments be exposed?
  4. Does attic space need ventilation?
  5. What is the difference between one product and another?
  6. How do I know if I've got an ice dam?
  7. What type of primer should I use on the roof deck when I am installing either AC TopSeal® Granular rolled roofing or AC TopSeal® RW rolled roofing?
  8. What type of primer should I use on the foundation wall when I am installing the AC HydroSeal 3000® waterproofing membrane product?
  9. Can I install the AC Granular Ice and StormSeal® underlayment over existing underlayment when re-roofing?
  10. What type of foam insulations can I use with AC HydroSeal 3000® waterproofing membrane?
  11. Do I have to prime foam insulations -- XPS – Extruded Polystyrene and ICF - Insulated Concrete Forms -- prior to application of AC HydroSeal 3000® waterproofing membrane? 
  12. What type of mastic should I use at the top edge and bottom edge of the AC HydroSeal 3000® waterproofing membrane and underneath the termination bar?
  13. What type of adhesive should I use on end laps?
  14. Can the HomeSeal® Self-Adhesive Roof/Gutter Repair Tape be painted?


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1. What is roofing underlayment?

Roofing underlayment is a rubberized membrane that goes under shingles to help prevent water penetration. It is the one piece of a roofing system that is expressly designed to be waterproof. Without an underlayment, water from wind-driven rain or ice dams can infiltrate under your shingles and severely damage your roof -- or even worse, the inside of your home. Roofing underlayments, widely regarded as the best in the industry, offer premium waterproofing protection.

2. How do I know which NEI® AC underlayment to use?

First, consider your climate and the kind of protection your home requires. Second, consider the finished roofing that will cover the underlayment. See below table.

AC Underlayments

Finished Roof Coverings

AC Granular Ice and StormSeal®

Asphalt Shingles
Wood Shakes
Quarry Slate Roofs

AC Metal/Shingle Ice and StormSeal™

Metal Roofing*
Asphalt Shingles
Wood Shakes
Quarry Slate Roofs


* For metal roofs, first check with the manufacturer for any special requirements.

3. How long can NEI® AC underlayments be exposed?

NEI® AC underlayments are not meant to be left permanently exposed to the sun. In general, the membrane should be covered with the final roof covering as soon as possible but within less than 30 days.

4. Does attic space need ventilation?

All of our peel’n stick underlayments are moisture and vapor barriers. Since ice build-up is partially a function of ventilation, the spaces under the covered deck area and the attic space must be ventilated in accordance with local building codes.

5. What is the difference between one product and another?

See the products section

6. How do I know if I've got an ice dam?

Ice dams form when warmth from inside the home melts the bottom layer of snow on the roof, sending water trickling down to the edge. Exposed to frigid air, it immediately refreezes, clogging gutters and causing the water behind it to pool up and find a path into the home below, usually through the shingles. Ice dams are more common in older or poorly insulated homes and those with low-pitch roofs. But even in newer homes, a new roof can leak if water runs backward in between the shingles.

7. What type of primer should I use on the roof deck when I am installing either AC TopSeal® Granular rolled roofing or AC TopSeal® RW rolled roofing?

SealBest® DrySeal (which can be purchased at a Menards store) manufactured by ThorWorks Industries or an SBS modified asphalt primer. Prime roof deck to enhance the bond of the rolled roofing to the substrate. Ensure all areas are primed prior to installing AC TopSeal® rolled roofing.

Carefully read the installation instructions provided with the primer before starting work. Follow the manufacturer's published installation recommendations, paying particular attention to environmental conditions, storage requirements, application rates, anticipated dry times and surface conditions at the time of rolled roofing application. While it is typically appropriate for primers to fully dry, some water based primers should dry only until the surface is dry but tacky, at which time the rolled roofing can be applied. Only prime the area that the rolled roofing can be applied to that day.

If an SBS modified asphalt primer is not available, SealBest® DrySeal manufactured by ThorWorks Industries, Inc., can be used as an alternative product with the following changes to the application:

  1. SealBest® DrySeal should be applied by brush or roller to the entire area to be covered by the rolled roofing.
  2. SealBest® DrySeal should be applied as a thin coating that completely covers the surface. The 60 mil (1.524 mm.) requirement by ThorWorks Industries is not needed when using SealBest® DrySeal as a primer underneath AC TopSeal® Granular rolled roofing or AC TopSeal® RW rolled roofing.
  3. SealBest® DrySeal should be allowed to dry until it is dry to the touch but does not transfer to your hand. The material will dry black.

CAUTION! Prior to drying, primer may wash off in a rain event. Primer will permanently stain finishes if washed onto adjacent surfaces.

8. What type of primer should I use on the foundation wall when I am installing the AC HydroSeal 3000® waterproofing membrane product?

SealBest® DrySeal (which can be purchased at a Menards store) manufactured by ThorWorks Industries or an SBS modified asphalt primer. Prime foundation to enhance the bond of the AC HydroSeal 3000® waterproofing membrane to the substrate. Ensure all areas are primed prior to installing AC HydroSeal 3000®.

Carefully read the installation instructions provided with the primer before starting work. Follow the manufacturer's published installation recommendations, paying particular attention to environmental conditions, storage requirements, application rates, anticipated dry times and surface conditions at the time of membrane application. While it is typically appropriate for primers to fully dry, some water based primers should dry only until the surface is dry but tacky, at which time the self-adhering membrane is applied. Only prime the area that the waterproofing membrane can be applied to that day.

If an SBS modified asphalt primer is not available, SealBest® DrySeal manufactured by ThorWorks Industries, Inc., can be used as an alternative product with the following changes to the application:

  1. SealBest® DrySeal should be applied by brush or roller to the entire area to be covered by the waterproofing membrane.
  2. SealBest® DrySeal should be applied as a thin coating that completely covers the surface. The 60 mil (1.524 mm.) requirement by ThorWorks Industries is not needed when using SealBest® DrySeal as a primer underneath AC HydroSeal 3000®.
  3. SealBest® DrySeal should be allowed to dry until it is dry to the touch but does not transfer to your hand. The material will dry black.

CAUTION! Prior to drying, primer may wash off in a rain event. Primer will permanently stain finishes if washed onto adjacent surfaces.

9. Can I install the AC Granular Ice and StormSeal® underlayment over existing underlayment when re-roofing?

No.

10. What type of foam insulations can I use with AC HydroSeal 3000® waterproofing membrane?

11. Do I have to prime foam insulations — XPS — Extruded Polystyrene and ICF — Insulated Concrete Forms — prior to application of AC HydroSeal 3000® waterproofing membrane?

No.

12. What type of mastic should I use at the top edge and bottom edge of the AC HydroSeal 3000® waterproofing membrane and underneath the termination bar?

Mastics are used to help protect the terminations, patches and overlaps in detail areas on the AC HydroSeal 3000®  waterproofing membrane. An SBS polymer modified mastic shall be used in all applications.  (Solvent based mastics cannot be used.)

13. What type of adhesive should I use on end laps?

Roofing Cement.

OR

An SBS polymer modified mastic (that does not contain solvents or vinyl) can be used to adhere membrane to membrane applications where there is a granular substrate surface or there is inadequate adhesion between the self-adhered membrane layers.  An SBS polymer modified mastic can be used in all applications. All mastics should comply with ASTM D4586.  Apply mastic with a trowel, forming a 1/8 in. (.32 cm.) thick layer. Do NOT over apply mastic. Clean off excess while still wet. Always form the lap into wet mastic.

14. Can the HomeSeal® Self-Adhesive Roof/Gutter Repair Tape be painted?

No.

 

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