Step 1.We should fill the gap on both sides of the floor expansion joint first with a foam backer rod so we don''t use as much filler.
When using foam backer rod, make sure it is wider than the gaps. The backer rod will prevent the filler from slowly sinking into the gaps and creating a low spot as it cures.
Step 2.Put masking tape around the aluminum frames,it can keep sealant off the floor expansion joint covers when filling and smoothing the sealant.
Step 3.Fill sealant into the gaps use a sealant gun.
Step 4.Smooth the sealant.
Step 5.Peel away the masking tape after the sealant is dry.