Hazdaz , 10 months ago I’d use some expanding foam if you could feel the air from the other side or see through it. You could also fill that area with silicone (which could also be used to help hold the flanged cover too.
I’d use some expanding foam if you could feel the air from the other side or see through it. You could also fill that area with silicone (which could also be used to help hold the flanged cover too.