Proper EPDM Lap Sealant Application: Mound it up for Long-Term Performance
Lap sealant is required around the edges of Versico’s Uncured EPDM Flashing and is an important part of the flashing detail. For long-term performance of the lap sealant, it is best to use the pre-formed plastic lap seal feathering tool provided in every box of Uncured EPDM Flashing. The lap seal feathering tool has a beveled V-shaped groove to create a rounded mound of lap sealant centered over the flashing edge.
A common mistake when using a cardboard feathering tool is flattening out the lap sealant bead from using too much pressure, or not forming a big enough groove. When lap sealant is flattened out to a thin layer, it is more prone to cracking from the natural expansion and contraction forces that occur on a roof. A major benefit of using the plastic feathering tool is that it doesn’t deform with added pressure, so you still achieve a rounded mound of lap sealant.
To ensure proper application, please follow these steps below which are also outlined on the GL300LS Lap Sealant Technical Data Bulletin.
A common mistake when using a cardboard feathering tool is flattening out the lap sealant bead from using too much pressure, or not forming a big enough groove. When lap sealant is flattened out to a thin layer, it is more prone to cracking from the natural expansion and contraction forces that occur on a roof. A major benefit of using the plastic feathering tool is that it doesn’t deform with added pressure, so you still achieve a rounded mound of lap sealant.
To ensure proper application, please follow these steps below which are also outlined on the GL300LS Lap Sealant Technical Data Bulletin.
- All surfaces to be sealed must be dry and free of oil, dust, or other foreign materials.
- Clean the area to be sealed with Weathered Membrane Cleaner to remove all foreign materials.
- Apply a 5/16” (8mm) bead of lap sealant along the outside edge of flashing.
- Use the plastic feathering tool to form a rounded mound of sealant directly over the flashing edge.
- Lap sealant may be applied immediately to Uncured EPDM Flashing.
- Lap sealant must be applied and feathered by the end of the working day.
