Underlayments are critical to the waterproofing integrity of roof systems. Bitec has underlayments for both residential and commercial applications.


Defend is a fiberglass reinforced underlayment that protects your home from water intrusion caused by melting snow or ice dams. Designed for residential use under shingles.

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MAT-40 is a highly durable tile and metal roof underlayment that resists punctures and tears, is easy to apply and provides superior waterproofing protection. Can be used in both residential and commercial applications.

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All values given are approximate and are subject to change without notice. There is no implied or express warranty given through these values, or statements, nor are there any assertions that the product purchased has been individually tested to conform to these standards. Testing is performed on a random basis, "in house" and at times with third party evaluation for the purpose of classification and or approval. Acceptance, purchase and selection of these products is the sole responsibility of the roofing contractor, architect, consultant, owner or buyer. We participate in UL and FMRC follow-up service in order to keep our classifications and approvals active.