Underlayment HT

PROTECT YOUR PROJECT - GUARD YOUR INVESTMENT
AEP Span Underlayment HT is a high-tensile strength, rubberized, asphalt underlayment specifically designed to withstand temperatures up to 250°F (121°C). Ideal for use under steel and aluminum metal roofing where a premium underlayment is desired.* This strong, skid-resistant membrane provides superior protection from water penetration caused by wind-driven rain and ice dams.

Features and Benefits:
1/4:12 minimum slope recommendation.
Protects the roof structure from water seepage caused by ice dams and wind-driven rain.
Withstands temperatures up to 250°F without degradation of the adhesive.
Seals around roofing nails, staples and screws.
Split-release film provides easier, faster installation.
Resists cracking, drying and rotting; providing long-term waterproofing performance and low lifecycle cost.
Concealed waterproofing system will not detract from the architectural aesthetics of the primary roofing system.
Exposed rubberized asphalt bead along the membrane edge ensures watertightness of lap seams.
180-day UV exposure resistance from time of installation.
Non-abrasive surface will not scratch or mar backside of panels through thermal movement.

Codes and Standards
UL Classified.
ICC-ES ESR #2206.
2018 International Building Code™
2019 California Building Code™
Meets ASTM D1970.
ASTM E108/UL 790 Class A Fire Resistance.
2019 California Building Energy Efficiency Standards, Title 24.
ICC/ASHRAE 700-2015 National Green Building Standard.

* Can also be used with copper and zinc roofing products.

AEP Span Underlayment HT is offered for all roofing products and is now required for all Full System Limited Weathertightness Warranties issued by AEP Span.

800-733-4955
www.aepspan.com

STORAGE
Roofing underlayment rolls should be stored upright, in a cool, dry location, protected from any inclement weather and temperature differentials. The temperature should be between 40° and 100°F (4.4° and 38°C). Do not double-stack pallets.

WARRANTY
AEP Span Underlayment HT products are backed by our defect warranty. AEP Span products will display optimal performance when stored under recommended conditions and used within one year of manufacture date. Products installed one year after date of manufacture are not covered under the defect warranty.

WEATHERTIGHTNESS LIMITED WARRANTY
AEP Span Underlayment HT is required for all Full System Weathertightness Limited Warranties issued by AEP Span and is specifically designed for use under all AEP Span metal roofing products. Visit our website for full warranty details.

INSTALLATION
AEP Span Underlayment HT is to be applied when the roof deck is dry, and the substrate temperature is 40°F (4.4°C) or higher.
At temperatures below 40°F, nailing or priming should be used to temporarily hold the membrane in place while adhesion develops.
Substrate must be free of any moisture. If moisture is present, it may inhibit adhesion. Prepare the roof deck by removing all loose objects, dirt, dust and debris. For re-roofing applications, remove all old materials from the roof deck in the area to be covered with AEP Span Underlayment HT. Replace water-damaged sheathing and sweep roof deck thoroughly.

PRIMING
Priming is not required on clean, dry wood, metal or most polyisocyanurate surfaces (polyiso paper facer does require priming). Masonry and exterior gypsum boards should be primed using an appropriate primer or adhesive.
Some rigid insulation boards with porous or dusty surfaces may require priming to promote initial adhesion. Priming is required on all substrates when air or substrate temperatures are below 40°F (4.4°C). Refer to your local building codes to determine acceptable product for use in your region.
Selection of roof deck or insulation substrate and/or use of a primer or adhesive are the responsibility of the architect, specifier or roofing contractor to determine based on the roof assembly and environmental conditions.

APPLICATION
Under water-shedding metal roof systems or low-slope metal roofs with a minimum ¼:12 minimum slope recommendation, start at the low point and apply AEP Span Underlayment HT over the full surface of the roof deck. Beginning at the eaves, apply underlayment from the low point to the high point of the roof, running the roll horizontally. The lap edge seams should be hand rolled to ensure maximum adhesion.

VALLEYS, HIPS & RIDGES
Cut roofing underlayment into manageable lengths. Align over the center of the valley, hip or ridge. Remove release film. Press the middle of the membrane first before working toward the edges. For open valleys, cover roofing underlayment with metal valley liners.

EAVES & RAKES
Cut AEP Span Underlayment HT into 10–15' pieces. Remove 2–3' of release film and align the edge of the membrane, sticky side down, so it overhangs the drip edge by 3/8" (10 mm). Continue to remove release film and press as you move across the roof. Use a hand roller and/or hand pressure to press into place. Overlap end laps a minimum of 6". The roofing underlayment should reach a point 2' inside the interior wall line. Local codes may require additional courses. If additional courses are required, the top lap must be at least 3½".

DRIP EDGES
At the rake edge, apply AEP Span Underlayment HT first and place drip edge on top. At the eave, apply drip edge first and place
underlayment on top of the drip edge so that it overhangs drip edge by 3/8" (10 mm) minimum.

LIMITATIONS
AEP Span Underlayment HT should be installed when air, roof deck and membrane temperatures are at or above 40°F (4.4°C).
AEP Span Underlayment HT should not be left exposed to sunlight for more than 180 days.
AEP Span Underlayment HT membrane should not be folded over the roof edge unless protected by a gutter or other flashing material.
Use caution during the installation of the membrane as it may become slippery when wet or covered with frost.
AEP Span Underlayment HT must not come in contact with PVC material.
AEP Span Underlayment HT is not designed for wall assemblies.

PRODUCT SPECIFICATIONS	
MINIMUM PRODUCT SLOPE	
Slope Recommendation	1/4:12 minimum slope	
  PHYSICAL PROPERTIES	
Surface Membrane
PRODUCT CHARACTERISTIC	White Engineered Polyolefin Composite Film with Factory-applied Anti-skid Coating
Modified Rubberized Asphalt
UNITS	RESULTS	
Roll Length	feet	66	
Roll Weight	lbs	55	
Roll Size	sq ft	198	
Roll Width	inches	36	
TYPICAL PERFORMANCE PROPERTIES	TEST METHOD	RESULTS	
Thickness	ASTM D1970	40 mils	
Low Temperature Flexibility	ASTM D1970	-45°F	
Adhesion to Plywood at 75°F	ASTM D1970	35 lbs/ft	
Lap Seam Adhesion at 75°F	ASTM D1970	21 lbs/ft	
Sealability Around Nail	ASTM D1970	Pass	
Slip Resistance	ASTM D1970	Pass	
Thermal Stability	ASTM D1970	Pass	
Moisture Vapor Permeance	ASTM D1970	0.02 perms	
Water Absorption	ASTM D1970	0.5%	
Tensile Strength Machine Direction	ASTM D412	250 psi	
Tensile Strength Transverse Direction	ASTM D412	1390 psi	
Elongation at Break Machine Direction	ASTM D412	250%	
Elongation at Break Transverse Direction	ASTM D412	170%	

25

Boxes (rolls) per pallet

  PACKAGING INFORMATION	

Underlayment HT

All information stated in the product sheet is correct at time of printing and subject to change without notice, check our website for the latest version.
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800-733-4955
www.aepspan.com