Do not caulk the underside of your siding i e caulk each piece of siding to the one beneath it.
Caulking split in siding joints.
Some of the most commonly caulked areas of siding include both corners and crevices as well as some butt joints and window and door trim boards.
Butt joints are a perfect example of poor joint design they re too small to accommodate a bond breaker so the caulk can t stretch properly once applied but they re also too large to simply leave alone.
Fill the area with patching compound.
Sometimes the old caulk in the siding joint is cracked and you need to cut the old caulk out with a razor knife.
A gap of 1 8 of an inch to 3 8 of an inch is necessary for the caulk to get into the crack and produce a good joint.
To patch holes and depressions in siding of any kind follow these steps.
Caulking them is a mistake and the caulking is likely to fail prematurely.
Your house s siding naturally expands and contracts and caulking it all together prevents this movement.
You can also use caulk to repair cracks in your siding.
This from installation instructions.
These siding joints can be caulked successfully if the gap is wide enough for the caulk to get into the crack.
The surface must be clean of dust and chalky paint.
Apply the compound to the hole or depression in one direction.
A lot of moisture from rain snow misdirected sprinklers or exuberant water fights can get in there enough to do some serious and expensive damage.
So just to review.
Water can seep in around butt joints and trim so these areas need to be caulked.
A caulk must be high quality in order to have the elasticity and adhesion necessary.
Bottom of siding boards should not be caulked water is meant to exit through the bottom of each board.
Sometimes the old caulk must be razor cut from these butt joints.
This allows for the caulk to get in and fill the gap correctly.
Clean the hole or depression you plan to fill.
Siding caulk can be used on several different areas of your exterior siding to help prevent water damage and moisture buildup.
Roughen the area you want to patch with 80 grit sandpaper for a better bond.
Another critical place is where the siding butts together in the middle of the wall.
If the siding joint is so tight that the caulk only bridges the gap it may split again.
While paint does tend to somewhat glue these pieces together caulking them is never advised and can cause permanent damage.
This is where the siding in the middle of the wall butts up against another piece of siding.
For regular hardiplank lap siding the kind you paint after installation caulking at butt joints is optional.
A high quality paintable caulk is recommended.
