Cold Weather Application Guidelines 2012
January 10, 2012
Cold temperatures change the physical properties of adhesives and sealants, and make roofing membranes stiffer and more difficult to work with. The information below is intended to help improve the successful application of roofing materials in cold weather.
1. ROOFING ADHESIVES, SEALANTS, AND PRIMERS
A. Storage
All liquid roofing materials must be stored between 60º and 80º F (15.6º and 26.7º C) until immediately before use, in order to ensure proper mixing and application. If the properties and application of the materials begin to deteriorate from cold weather exposure, restoring them to room temperature will be necessary. It could take several days of warm storage until cold adhesives, sealants, and primers are restored to room temperature. Moreover, materials stored cold, followed by room temperature storage, may have separated; and, if so, will need to be re-mixed. Never allow water-based products (Water Based Bonding Adhesive P; AcryliTop™ PC-100 coatings and Base Coat) to freeze.
B. Cold Weather Dispensing
When liquid materials are cold, their viscosity rises; solids and polymers can settle, and this separation of the solvents can make mixing and dispensing very difficult. Most liquid roofing products should be applied only when ambient and substrate temperatures are minimum 40º F (4.4º C) and rising (California’s Southcoast Air Quality Management District requires that substrate and ambient temperatures exceed 45° F (7.2º C) at the time of application).
However, some products should never be used in cold temperatures and when temperatures below freezing are expected within 48 hours after application. Such Firestone materials are: Water Based Bonding Adhesives; AcryliTop™ Coatings; Single-Ply LVOC Bonding Adhesive-1168; I.S.O.FIX™ Adhesive; I.S.O.SPRAY™ S Adhesive; I.S.O. Twin Pack™ Adhesive; I.S.O.Stick™ Insulation Adhesive, and XR Stick™ Adhesive for UltraPly™ TPO XR membrane. With proper precautions, many solvent based adhesives, sealants and primers can be used below 40º F (4.4º C) provided proper storage and application procedures are followed.
To minimize the potential for materials cooling on the roof before application:- Only bring materials to the roof that can be used within 2 to 4 hours.
- Always thoroughly mix adhesives and primers to a uniform, smooth state before and during use (follow mixing instructions provided with each product, and do not use any mixing equipment that could generate a spark resulting in ignition of flammable material).
- Keep adhesives, sealants, primers as close to room temperature as possible during application.
- Dispensing equipment which may contain adhesive within hoses (i.e., sprayers, power rollers, etc.) should be maintained at room temperature as well, or hoses properly heated/jacketed to maintain proper adhesive dispensing temperature. Hoses should be thoroughly cleaned after every use to minimize the possibility of residual product within the hoses.
Drying times depend on ambient conditions; cool and overcast conditions will lengthen open times, while sunny and dry conditions shorten open times. Expect and plan for longer open times in cooler weather. Solvent blisters can occur if membrane is mated while the solvents in the adhesive/primer are not sufficiently dried.
C. LVOC Products
To achieve Low Volatile Organic Compound (LVOC) status, materials must use highly engineered solvents that meet rigorous environmental criteria. Two of the most common LVOC solvents are Tertiary Butyl Acetate (TBAc) and Parachlorobenzotrifluoride (PCBTF). Water-based products can also be used to achieve LVOC status. LVOC products tend to be sensitive to ambient conditions, and have varying flash-off times that are different from higher VOC products:
D. Adhesive “Blushing”
Blushing occurs when the evaporative cooling of the material during dry time lowers the surface temperature at, or below, the dew-point, resulting in condensation formation on the adhesive/primer film. When “blushing” occurs, the condensation on the adhesive/primer will not allow adhesion. The use of adhesives/primers should be closely monitored when the ambient temperature is relatively close to the dew-point, typically in the early morning and late afternoon. The use of adhesives/primers should be scheduled for midday to take advantage of the best adhesive application conditions of the workday; midday sun; ambient and dew-point temperatures furthest apart.
E. Asphalt and MB Multi-Purpose Cold Adhesive Products
Application of SBS and BUR membranes in hot asphalt at ambient temperatures below 40° F (4.4° C) requires special handling and application techniques. Cold substrates can receive cool mopping asphalt at a rapid rate. Asphalt cools and thickens more quickly as the temperature decreases, will not flow well, and may fail to yield a uniform application rate. When hot asphalt is used as the method of attachment, sheets may be attached to an appropriate substrate using ASTM D 312 Type III (3) or Type IV (4) or IV CSA A123.4 Type III (3) or Type IV (4) asphalt or Firestone SEBS Mopping Asphalt.
The following cold weather application procedures are to be used when the temperature at the time of application is below 50° F (10° C). - Firestone does not recommend the use of hot asphalt when the outside temperature is below 32° F (0° C) or when wind speeds exceed 10 miles (16 km) per hour at ambient temperatures below 40° F (4.4° C).
- All asphalt handling equipment should be insulated in order to minimize the drop in asphalt temperature prior to application.
- Roofing membranes should be stored between 60° F and 80° F (15.5° C and 26.6° C) for a minimum of 24 hours before installation.
- Materials must be used within four hours of removal from a heated storage area.
- If materials are not used within 4 hours they must be returned to a heated storage area until they return to a temperature of 60° F to 80° F (15.5° C and 26.6° C). The time required for roofing materials to return to the proper temperature for use is typically 24 hours.
- Mop lead should be reduced to no more than 5 feet (1.5 meters) from the roll.
- Roll cap sheets into hot asphalt using positive pressure, assuring proper side and end lap width.
- A minimum asphalt temperature of 420° F (216° C) must be maintained at the point of application of the roofing membrane.
- Stop the operation and/or change to another container when asphalt temperature, at the point of application, can not be maintained at 420° F (216° C).
- Never overheat asphalt to compensate for cold weather conditions, and never heat asphalt above its final blowing temperature or its flash point.
Firestone does not manufacture or supply oxidized asphalt and does not warrant the performance of products Firestone does not supply. Always follow all OSHA and NRCA safety regulations.
Firestone Multi-Purpose MB Cold Adhesive is best applied in cold weather by use of a heated spray rig. Squeegee-applied Cold Adhesive in temperatures below 40° F (4.4° C) is not recommended. Ambient and substrate temperatures should be 40° F (4.4° C) and rising at the time of application. Installation in temperatures colder than 40° F (4.4° C) should only be attempted when the adhesive pails are maintained at 60° F and 80° F (15.5° C and 26.6° C) until immediately prior to application. Firestone MB Flashing Cement should be used when temperatures are 40° F (4.4° C) and rising.
2. ROOFING MEMBRANES
A. Membrane size
During colder weather, folded membrane panels become more difficult to relax and install, especially with adhered systems. The use of no-fold panels is highly recommended. Always unfold single-ply membrane panels and roll out modified bitumen and BUR rolls in order to allow the membranes to fully relax prior to installation.
B. UltraPly TPO Installation
To ensure that seams are properly welded when using an automatic welder, it is critical that test welds are done 1) at start-up, 2) whenever ambient conditions change, and 3) if welding is stopped for a significant period of time (lunch breaks, etc.). When using a hand welder, test welds should be performed on scrap membrane or flashing material to ensure that the operator is using the proper technique and temperature setting.
TPO membrane can become stiffer in colder temperatures. To help relax TPO membrane and increase its flexibility, remove the white wrapping on the roll early in the day that the membrane is to be installed and leave the roll in the sunlight as long as possible before installation. This will enable the dark bottom ply on the TPO membrane to absorb as much heat as possible and help the TPO membrane to relax and become more flexible.
C. RubberGard EPDM Flashing Installation
Uncured EPDM flashing products are designed to be formable during warmer temperatures, but in cold weather, supplemental warming may be needed. This warming can be achieved by using a heat gun during application. Care should be taken to keep any heat gun away from cleaners, primers, adhesives or other flammable materials. Ambient conditions (sunlight, wind, and temperature) and flashing color will determine the need for supplemental heat. Typically, temperatures below 60° F (15.5° C) may require the use of an additional heat source to ensure the formability of uncured flashing products.
D. SBS, APP, and BUR Installation
SBS and APP modified bitumen products, and BUR ply felts, should be stored between 60° F - 80° F (15.5° C and 26.6° C) and installed when ambient and substrate temperatures are 40° F (4.4° C) and rising. Attempting to install these asphalt-based products in colder temperatures can reduce adhesion and cause disbonding or blistering during subsequent heating cycles.
For further information and assistance please contact your Firestone Technical Coordinator at 1-800-428-4511.
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