All,
I was getting ready to install a new slider in an existing opening and realized that the gap at the top is about an inch. I’d rather shim the header down than the floor up. Is it advisable to scab a 5/4 pice of lumber onto the bootm of the header and flush with the sheathing to give something to screw the nailing flange to?
Thanks,
Cam
Replies
Cam
Yes, whatever it takes to make a sound installation.
In addition, don't forget to take your flashing membranes down to the proper level and underlap what's there now.
I'd add enough ply to allow good purchase of screws holding the flange on, but as much room as possible for spray foam. While in some areas I think the rule is to allow very minimal room between windows/doors and the rough opening for resistance to extreme wind conditions, in general it seems to be better overall to allow room for good insulation. The metal tip on my foam gun requires about 3/8" so that's what I normally shoot for, but disposible cans have a much smaller tube so 1/4" is probably plenty.