January 1998Revised January 2000

Page 1 of 4

SAFEGUARDING TORCH-APPLIED ROOF INSTALLATIONS

Table of ContentsPage

1.0 SCOPE ................................................................................................................................................... 21.1 Changes .......................................................................................................................................... 2

2.0 LOSS PREVENTION RECOMMENDATIONS ....................................................................................... 22.1 Human Element ............................................................................................................................... 22.2 Equipment and Processes .............................................................................................................. 32.3 Protection ......................................................................................................................................... 32.4 Construction and Location ............................................................................................................... 4

3.0 SUPPORT FOR RECOMMENDATIONS .............................................................................................. 44.0 REFERENCES ....................................................................................................................................... 4

4.1 FM Global ........................................................................................................................................ 44.2 NFPA Standards .............................................................................................................................. 4

APPENDIX A GLOSSARY OF TERMS ....................................................................................................... 4APPENDIX B DOCUMENT REVISION HISTORY ....................................................................................... 4APPENDIX C ADDITIONAL INFORMATION .............................................................................................. 4

FM GlobalProperty Loss Prevention Data Sheets 1-33

©1999 Factory Mutual Insurance Company. All rights reserved. No part of this document may be reproduced,stored in a retrieval system, or transmitted, in whole or in part, in any form or by any means, electronic, mechanical,photocopying, recording, or otherwise, without written permission of Factory Mutual Insurance Company.

1.0 SCOPE

This data sheet describes design considerations and precautions that should be taken during the installationof torch-applied roof systems for new construction or re-roofing.

1.1 Changes

January 2000. This revision of the document has been reorganized to provide a consistent format.

2.0 LOSS PREVENTION RECOMMENDATIONS

2.1 Human Element

2.1.1 Torches used to secure roofing membranes should be used according to manufacturers’ recommen-dations. The flame from a hand-held torch should be constantly moved from side to side. If a mobile heat-ing apparatus is used, it should be kept in constant motion while operating. The exposed outer surface of themembrane coil should be heated until a slight sheen develops. To prevent smoldering or ignition ofmembranes, they should not be overheated. A slight smoke vapor can be seen when the compound isoverheated.

2.1.2 Caution should be used when working around roof openings, penetrations, or flashings. Wood nailers,cant strips, and metal flashing should not come in direct contact with the flame of the torch. Small torchesshould be used to heat the underside of the membrane away from these areas before securement. Hot trowels(electric trowels or trowels heated by a torch) should be run along seams at laps and flashing to soften theadhesive. The torch should not be used in areas where the flame impingement cannot be fully viewed. Openflames should not be left unattended. Roof openings/vents should be covered with a stable noncombus-tible cover to prevent ignition of building contents as well as personal injury.

Extreme caution should be used near penetrations such as exhaust vents. Flames could ignite grease andlint accumulations. Such accumulations should be cleaned before roofing work is started.

Air conditioning units and ventilating fans should be shut down before torch work is done in surroundingareas.

Expansion joints should be filled with mineral wool or ceramic fiber with a steel cover plate below.

2.1.3 A torch stand should be used to direct the flame upward when momentarily not in use. The cylindervalve should be closed to burn off propane in the line before shutting off the torch head. The gas supply shouldbe shut off whenever a propane odor is detected.

2.1.4 Installations should be coordinated with concerned parties, and close supervision should be provided.

2.1.5 Torches should not be used near gas lines, electrical wires, or flammable liquids during roofconstruction.

2.1.6 The torch flame should not be applied to a combustible substrate when installing the membrane. OnlyFactory Mutual Research Approved1 assemblies should be used. When foam plastic, kraft-faced glass fiber,or wood fiber insulation or cant strips, or plastic fastener plates are to be used, they should be covered witha minimum 40 lb (18.2 kg) organic felt base sheet or a glass fiber felt base sheet adhered with hot asphaltbefore the torch applied membrane is installed. A full mop of hot asphalt should be used, unless the sys-tem is specifically listed in the Factory Mutual Research Approval Guide for base sheet installation, using astrip or spot mopping of asphalt or mechanical securement. Torch flames should not come in contact withexposed plastic roofing cement.

References to ‘‘Approved’’ in this data sheet means the products and services have satisfied the criteria for FactoryMutual Research Approval. Refer to the Approval Guide for a complete listing of products and services that areFactory Mutual Research Approved.

1-33 Safeguarding Torch-Applied Roof InstallationsPage 2 FM Global Property Loss Prevention Data Sheets

©1999 Factory Mutual Insurance Company. All rights reserved.

2.2 Equipment and Processes

2.2.1 Proper equipment should be used to heat roofing membranes. Torches should be equipped with apilot adjustment, flame height adjustment, 25 to 50 ft (7.6 to 15.2 m) of approved or listed hose, pressuregauge, and regulator. A spark igniter should be used. Torch trolleys and multiple torch head machines shouldbe equipped with listed safety valves.

Safety caps should be tied to all propane cylinders and installed on the valves whenever cylinders are notin use. Carts used to transport propane cylinders should be stable. Tall, narrow, standing cylinders should bechained against walls or in proper carts.

2.2.2 The propane cylinder should be adequately sized for the torch used. If frost buildup occurs on pro-pane cylinders and the rate of vapor withdrawal is no longer adequate for operating conditions, the cylin-der should not be placed on its side or heated with the torch flame. The hose should be disconnected anda larger cylinder used. Liquid propane cylinders may be of either the vapor withdrawal or liquid withdrawaltype. With the vapor withdrawal type, vapor is drawn off from the torch head. Vapor withdrawal cylindersare equipped with female cylinder valves. Liquid withdrawal cylinders transfer the liquid, via a siphon tube,from the cylinder to the torch head where it is vaporized. Liquid withdrawal cylinders have male cylindervalves, which may be equipped with adapters.

Frost buildup occurs only with vapor withdrawal cylinders. This buildup can be the result of an undersized cyl-inder or low air temperatures. When vapor is drawn off more quickly than it is replaced, heat is absorbedand frost buildup occurs on the outside of the cylinder. Vapor pressure then further declines. Consequently, liq-uid withdrawal cylinders are preferred. However, if vapor withdrawal cylinders are used, or if temperaturesare low (below 20°F, - 7°C), 40 or 100 lb (18.2 or 45.5 kg) cylinders should be used with larger torches (suchas those used on the field of the roof).

2.2.3 Equipment should be thoroughly inspected and repaired or replaced as needed. Propane cylindersshould be inspected for dents. If dents larger than 1 in. (25 mm) in diameter are found, the cylinder shouldbe replaced. Torch and cylinder connectors should be visually inspected and checked for leaks with a soapand water solution. An open flame should not be used to test for leaks.

Leaky equipment should not be used. Regulator adjustments and pressure gauges should be checked toensure they are operable. The vent on the regulator should be checked to ensure it is not blocked. If anunstable flame occurs (one which roars loudly and tends to blow itself out), the equipment should be repairedor replaced immediately.

2.2.4 Propane cylinders should not be hoisted by their valves. Straps placed around the cylinders shouldutilized.

2.2.5 A fire watch should be conducted for at least one hour after torch work has been completed. All roofareas worked on should be checked for hot spots and signs of smoldering. If available, infrared roof scan-ners should be used. The inside of the building should also be inspected for signs of fire or smoke. All ‘‘hotspots’’ or fires, even if extinguished, should be reported to the fire department. Smoldering may continue afterextinguishment, may take place for hours before flaming begins, and may take place in areas unsus-pected by the layman.

2.2.6 Fuel containers, burners, and related appurtenances of roofing equipment in which liquefied petro-leum gas is used for heating should comply with Data Sheet 7-50, Compressed Gases in Cylinders; and NFPA58, Liquefied Petroleum Gas Code.

All fuel containers should be located at least 10 ft (3 m) from the burner flame or at least 2 ft (0.6 m) awaywhen properly insulated from heat or flame.

2.3 Protection

2.3.1 There should be at least one 10 lb (4.5 kg) multipurpose dry chemical portable extinguisher within20 ft (6.1 m) horizontal travel distance of torch-applied roofing equipment. For large roof areas, additionalprotection such as charged hose lines or additional extinguishers should be provided as practical.

Safeguarding Torch-Applied Roof Installations 1-33FM Global Property Loss Prevention Data Sheets Page 3

©1999 Factory Mutual Insurance Company. All rights reserved.

2.4 Construction and Location

Before re-roofing over an existing built-up roof (BUR), follow all application recommendations. Additionaldetails on the following recommendations can be found in Data Sheet 1-29, Above-Deck Roof Components.

2.4.1 Before re-roofing over a gravel or slag surfaced BUR, the surfacing material should be power broomedand removed. In addition, a moisture survey should be conducted, and wet areas should be replaced.

2.4.2 When applying a torch applied roof cover over an existing BUR, blistered and broken areas shouldbe repaired first. If the original roof insulation was not properly mechanically fastened throughout the roof, oneof the following should be done:

a) Mechanically fasten the existing roof with Approved fasteners driven through new insulation and/orthe existing covering and steel deck. The re-roofing system can then be applied. Fasteners with steel platesshould be used. Or,

b) Conduct uplift tests on the existing roof in accordance with Data Sheet 1-52, Field Uplift Tests, (uplifttests can be waived if previously done) and mechanically fasten if tests fail.

For both above, the mechanical fastener should be slightly recessed into the existing covering or coveredwith a patch of felt before the new covering.

3.0 SUPPORT FOR RECOMMENDATIONS

Documented losses exist of fires started by roofer’s torches during the installation of torch-applied roof sys-tems. These losses support the need to follow the recommendations in this data sheet.

4.0 REFERENCES

4.1 FM Global

Factory Mutual Research Approval Guide.Data Sheet 1-29, Above-Deck Roof Components.Data Sheet 1-52, Field Uplift Tests.Data Sheet 7-50, Compressed Gases in Cylinders.

4.2 NFPA Standards

NFPA 58, Liquefied Petroleum Gas Code.

APPENDIX A GLOSSARY OF TERMS

This document does not have any defined terms.

APPENDIX B DOCUMENT REVISION HISTORY

This document does not have any revision history.

APPENDIX C ADDITIONAL INFORMATION

Torch-applied roof systems are modified bituminous roofing systems using membranes adhered by heatingwith a torch and melting an asphalt back-coating, instead of mopping hot asphalt. Torch-applied roofing maybe a potentially hazardous construction process, and extreme caution should be exercised during installation.

A modified bitumen membrane has been developed that can be secured using an electric heating ele-ment. This system cannot be recommended yet, because it has not been tested by Factory Mutual Researchfor fire classification, fire spread across the top surface, wind uplift, etc.

FM Engr. Comm. April 1988

1-33 Safeguarding Torch-Applied Roof InstallationsPage 4 FM Global Property Loss Prevention Data Sheets

©1999 Factory Mutual Insurance Company. All rights reserved.