What is roofing underlayment used for?

Roofing underlayment is installed below the final roof covering to help protect the roof deck from construction moisture and wind-driven rain.

Is it suitable for OEM supply?

Yes. KOSITE supports OEM roll packing, label discussion, sample checking and export quotation.

Overlap direction, roof slope, fixing density, edge treatment and compatible sealing accessories should be confirmed.

Home > Products > Roofing Underlayment

Synthetic Roofing Underlayment

KOSITE supplies synthetic roofing underlayment and waterproof roof-membrane roll goods for roof-deck protection, OEM programs and export packing.

UseRoof deck and underlayment protection

GSM / Basis Weight100-260 gsm, selected by roof system and strength requirement

Roll WidthCommon 1.0-1.5 m; custom width by order

Roll Length50 m, 100 m or custom roll length

SurfaceSmooth, anti-slip or printed surface option

FunctionWater-resistant roof membrane support

SupplyRoll goods with export packing options

SupportSamples, data sheet and quotation follow-up

Used below the final roof covering as a secondary water-management layer for roof-deck protection.
Suitable roll construction depends on the roof profile, slope, installation method and expected exposure before covering.
GSM, roll format, surface, printing and export packing can be set for distributor, contractor and OEM programs.

Roofing underlayment must be selected as part of the roof build-up, not only by basis weight. Roof deck, covering profile, insulation position and temporary exposure affect the choice.
Compare water resistance, tensile and tear strength, surface grip, roll handling and fastening method for the intended roof system.
Laps, edge details, penetrations and compatible tapes or flashings determine whether the installed underlayment remains continuous.

Confirm the roof build-up, roof slope, covering profile, insulation position and expected exposure before selecting a roll structure.
Specify the required water resistance, vapor behavior, tensile strength, tear strength and surface-finish requirements.
Set roll width, roll length, core size, printing, label and pallet or container-packing requirements.
Review lap direction, fixing method, edge treatment, penetrations and compatible tape or flashing before installation.
Confirm applicable product data, test references and destination-market requirements before production.
Approve a sample before bulk supply, especially for private-label or project-specific programs.

Use these application notes with the selected product data sheet and project specification.