Self-adhered underlayment for premium protection

Product Description

GRACE ICE & WATER SHIELD® has been the premier self-adhesive underlayment product used in domestic roof protection under shingles for more than 30 years. It has performed in the critical areas under the most severe climatic conditions to protect against wind-driven rain and the effects of ice dam build-up beneath the shingles.

Because of the unique properties of Grace Ice & Water Shield, these benefits are also applicable in its use under a wide range of metal roofing materials, on low and high slope designs.

Product Description

Grace Ice & Water Shield membrane is composed of two waterproofing materials - an aggressive rubberised asphalt adhesive backed by a layer of high density, cross-laminated polyethylene. The rubberised asphalt surface is backed with a release paper that protects the adhesive quality. During application, the release paper is removed allowing the compound to bond tightly to the plywood deck. The membrane is supplied in 20m rolls, 1m in width.

Product Advantages

  • Easy to handle and apply
  • Foldless release paper
  • Seals around nails
  • Dual barrier protection
  • Membrane will not crack, dry out or rot
  • Protects under all standard sloped roof coverings
  • Slip-resistant surface
  • Proven track record
  • Re-roofable
  • GCP technical support

Features & Benefits

  • Easy to handle and apply – The self-adhesive membrane bonds firmly to the roof deck without heat or special adhesives.
  • Foldless release paper – The foldless release paper provides multiple performance enhancements: fewer edge catches, 180° pull-back, ease of membrane cutting (single cuts) and membrane positioning, quicker “one-man installs” resulting in an easier, more productive release.
  • Seals around nails – The rubberised asphalt layer in Grace Ice & Water Shield seals around roofing nails, resisting leakage caused by water back-up behind ice dams, or from wind-driven rain.
  • Dual barrier protection – Rubberised asphalt and polyethylene are combined to form two waterproofing barriers providing maximum protection.
  • Membrane will not crack, dry out or rot – Grace Ice & Water Shield resists attacks from fungus and bacteria; maintains its integrity for long-lasting protection.
  • Protects under all standard sloped roof coverings – Grace Ice & Water Shield protects under slate, tile, cedar shakes or metal, as well as under conventional asphalt shingles.
  • Slip-resistant surface – Grace Ice & Water Shield has a slip-resistant, embossed surface to maximise traction and safety for applicators.
  • Proven track record – Grace Ice & Water Shield is the name brand in roofing underlayments with a 30-year track record of protecting roofs from ice dams and wind-driven rain.
  • Re-roofable – Unlike some granular surfaced membranes, Grace Ice & Water Shield will not adhere to the underside of the exposed roof covering. Grace Ice & Water Shield can be applied over the old underlayment (except over BASIK®) in retrofit applications, making reroofing easier, less costly (since there is no need for removing the existing underlayment), more durable and environmentally friendly (as the structural deck remains intact avoiding the need to purchase additional wood decking).
  • GCP technical support – Grace Ice & Water Shield is backed by a team of local technical support personnel that help ensure every application goes smoothly.

Physical Properties

Property Typical Values Test Method
Colour Grey-Black -
Nominal Thickness* 1mm ASTM D 3767 Method A
Tensile Strength of Membrane 2N / mm2 ASTM D 412 (Die C Modified)
Elongation Break of Membrane 200% ASTM D 412 (Die C Modified)
Low Temperature Flexibility Unaffected @ -29°C ASTM D 1970
Adhesion to Plywood 525N /m ASTM D 903
Permeance 2.5ng / msPa (0.08 Perms) ASTM E 96

* Nominal thickness refers to the thickness of the membrane without release liner.
** Typical test values may represent average values from samples tested. Test methods noted may be modified. The test is run at a rate of 50mm per minute.

Installation Procedure

Surface Preparation

Install Grace Ice & Water Shield directly on a clean, dry, continuous structural deck. Some suitable deck materials include plywood, wood composition, wood plank, metal, concrete, or gypsum sheathing. Remove dust, dirt, loose nails, and old roofing materials. Protrusions from the deck area must be removed. Decks shall have no voids, damaged, or unsupported areas. Wood planks should be closely butted together. Repair deck areas before installing the membrane.

Prime concrete, masonry surfaces and DENSGLASS GOLD® with PERM-A-BARRIER® WB Primer. Prime wood composition and gypsum sheathing with Perm-A-Barrier WB Primer if adhesion is found to be marginal (refer to Technical Letter 12, Use on Oriented Strand Board (OSB) Roof Sheathing). Apply Perm-A-Barrier WB Primer at a rate of 6 to 8m2 / L. Priming is not required for other suitable surfaces provided that they are clean and dry.

Membrane Installation

Apply Grace Ice & Water Shield in fair weather when the air, roof deck, and membrane are at temperatures of 5°C or higher. Apply roof covering material at temperatures of 5°C or higher.such as along the eaves or in valleys and in climates where severe ice dams are anticipated. Apply the membrane to the entire roof deck for wind-driven rain protection. Apply a new layer of Grace Ice & Water Shield directly over the old underlayment in retrofit applications following the standard membrane application procedure.

Cut the membrane into 3 to 5m lengths and reroll loosely. Peel back 300 to 600mm of release liner, align the membrane, and continue to peel the release liner from the membrane. Press the membrane in place with heavy hand pressure. Side laps must be a minimum of 90mm and end laps a minimum of 150mm. For valley and ridge application, peel the release liner, centre the sheet over the valley or ridge, drape, and press it in place. Work from the centre of the valley or ridge outward in each direction and start at the low point and work up the roof.

Alternatively, starting with a full roll of membrane, unroll a 1 to 2m piece of membrane leaving the release liner in place. Align the membrane and roll in the intended direction of membrane application. Carefully cut the release liner on top of the roll in the cross direction being careful not to cut the membrane. Peel back about 150mm of the release liner in the opposite direction of the intended membrane application exposing the black adhesive. Hold the release liner with one hand and pull the roll along the deck with the release liner, leaving the applied membrane behind. Use the other hand to apply pressure on the top of the roll. Stop frequently to press the membrane in place with heavy hand pressure. When finished with the roll go back to the beginning, re-roll and pull the remaining release paper from the material, finishing the installation. For successive membrane courses, align the edge of the release liner with the dashed line provided on the surface of the membrane to achieve the 90mm side lap.

Consistent with good roofing practice, install the membrane such that all laps shed water. Always work from the low point to the high point of the roof. Apply the membrane in valleys before the membrane is applied to the eaves. Following placement along the eaves, continue application of the membrane up the roof. The membrane may be installed either vertically or horizontally.

Use smooth shank, electro-plated galvanised nails for fastening shingles to get the best seal. Hand nailing generally provides a better seal than power-activated nailing.

If nailing of the membrane is necessary on steep slopes during hot or extreme cold weather, backnail and cover the nails by overlapping with the next sheet.

Extend the membrane on the roof deck above the highest expected level of water back-up from ice dams and above the highest expected level of snow and ice on the wall sheathing on vertical side walls (dormers) and vertical front walls for ice dam protection. Consider a double layer of membrane in critical areas,

  • Not compatible with EPDM or TPO; use Grace Ultra for tie-ins (refer to Technical Letter 5, Chemical Compatibility).
  • Not compatible with polysulfides, flexible PVC, or high concentrations of resin (pitch). For more information, refer to Technical Letter 5.

Precautions and Limitations

  • Slippery when wet or covered by frost.
  • Consistent with good roofing practice, always wear fall protection when working on a roof deck.
  • Release liners are slippery. Remove from work area immediately after membrane application.
  • Do not leave permanently exposed to sunlight. Cover within 90 days.
  • Place metal drip edges or wood starter shingles over the membrane.
  • Do not fold over the roof edge unless the edge is protected by a drip edge, gutter or other flashing material.
  • Do not install on the chamfered edges of wood plank.
  • Do not install directly on old roof coverings.
  • Certain product applications are prohibited in hot desert areas. Check with your local GCP representative.
  • Check with the manufacturer of the metal roofing system for any special requirements when used under metal roofing. Do not install directly under roof coverings especially sensitive to corrosion, such as zinc, without providing proper ventilation.
  • Do not install under copper, COR-TEN®, or zinc metal roofing in high altitudes. These roofs can reach extremely high temperatures due to the low reflectivity, high absorption, and high conductivity of the metals. Use Grace Ultra for these roof types. Check with your local GCP representative.
  • Provide proper roof insulation and ventilation to help reduce ice dams and to minimise condensation. Grace Ice & Water Shield is an air and vapour barrier.
  • Repair holes, fishmouths, tears, and damage to membrane with a round patch of membrane extending past the damaged area 150mm in all directions. If fasteners are removed leaving holes in the membrane, they must be patched. The membrane may not self-seal open fastener penetrations.
  • Do not install fasteners through the membrane over unsupported areas of the structural deck, such as over the joints between adjacent structural panels.
  • Due to its slight asphaltic odour, do not apply where the membrane is exposed to interior living space. Refer to product literature for more complete information.

Code Compliance

Grace Ice & Water Shield meets the following standards:

  • Underwriters Laboratories Inc. Class A fire classification under fibre-glass shingles and Class C under organic felt shingles (per ASTM E108/UL 790)
  • Underwriters Laboratories Inc. Classified Sheathing Material Fire Resistance Classification with Roof Designs: P225, P227, P230, P237, P259, P508, P510, P512, P514, P701, P711, P717, P722, P723, P732, P734, P736, P742, P803, P814, P818, P824
  • Miami-Dade County Code Report NOA 09-0107.08
  • Canadian Construction Materials Centre (CCMC) 12693-R
  • U.S. Department of Housing and Urban Development (HUD) Materials Release 1068g
  • City of Los Angeles RR 25330
  • Florida State Approval Report No. FL298-R3
  • International Code Council Evaluation Services (ICC-ES) Report No. ESR-1677


Pack Size 1m x 20m roll (20 sqm)
Gross Weight 26kg
Storage Dry conditions below +35oC

Health and Safety

GCP Applied Technologies is certified to ISO 9001 by TUV SUD PSB Pte Ltd.

Technical Services

For assistance with working drawings for projects and additional technical advice, please contact GCP Applied Technologies. | Thailand customer service: 66 2 030 9700

We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate, and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations, and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation, or suggestion is intended for any use that would infringe any patent, copyright, or other third party right.

Grace Ice & Water Shield, Tri-Flex 30, Basik, Perm-A-Barrier, Grace Ultra, Ripcord, Cor-Ten and DenGlass Gold are trademarks, which may be registered in the United States and/or other countries, of GCP Applied Technologies, Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

© Copyright 2017 GCP Applied Technologies, Inc. All rights reserved.


GCP Applied Technologies Inc., 2325 Lakeview Parkway, Alpharetta, GA 30009, USA
GCP Applied Technologies Holdings (Thailand) Limited., 848 Moo 2, Bangpoo Industrial Estate (North), Phraksa Mai, Muang Samutprakarn, Samutprakarn 10280, Thailand
This document is only current as of the last updated date stated below and is valid only for use in Thailand. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

Last Updated: 2023-07-07