UL 1897

UL 1897, Standard for Safety, Uplift Tests for Roof Covering Systems, is a North American test method maintained by UL Standards & Engagement. It evaluates how well a roof covering and its means of attachment, such as fasteners, plates, clips or adhesive, resist wind uplift.

Method

A roof covering system is installed over a test frame and placed in a chamber. Static uplift pressure is raised in steps and held at each step while any vertical movement is recorded. Test laboratory Intertek describes the increments as no more than 15 psf (0.72 kPa), each held for at least 1 minute. The test is normally run until something fails, for example loss of adhesion, fastener pull-out, seam disengagement or metal fatigue, so the result is a measured ultimate pressure rather than a pass/fail class.

What it covers

UL 1897 is used for a wide range of products, including:

• single-ply membranes (mechanically fastened or adhered)
• built-up and modified bitumen systems
• standing seam metal roofs
• metal and composite shingles

Relationship to other wind tests

The International Building Code lists UL 1897 alongside UL 580 and FM 4474 as acceptable methods for membrane roof systems. UL 580 gives fixed classes up to Class 90; UL 1897 is often used where design pressures exceed what a Class 90 rating demonstrates, or where an engineer needs the actual failure pressure to apply a safety factor.

Because the test applies static pressure, it does not reproduce the gusting and cycling of real wind. Dynamic tests such as CSA A123.21 in Canada were developed partly for that reason, especially for mechanically attached membranes that flutter.

Using results

A UL 1897 report states the maximum pressure the specific assembly withstood. Designers usually divide this by a safety factor to obtain an allowable design pressure, then compare it with site-specific wind loads calculated under ASCE 7 or the applicable code. The result only applies to the exact configuration tested.