Watch this graphic depiction of the removal and replacement of hardboard siding.
Caulking pressboard siding.
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.
Water is meant to exit through the bottom of each board.
The siding expands and contracts with temperature and humidity.
Bottom of siding boards should not be caulked.
In my opinion caulking between the seams in any lapped siding either horizontal or vertical is not good practice but not just because of any potential vapor barrier effect.
While paint does tend to somewhat glue these pieces together caulking them is never advised and can cause permanent damage.
However once water has penetrated hardboard siding and deterioration has begun the siding will eventually need to be replaced.
It needs to move and breathe.
If your pressboard siding is not showing severe signs of problems but does have a few indications of water penetration slight discoloration rusted nails etc the process of deterioration can sometimes be slowed by the regular application of paint and or caulk.
Trim the tip of the tube of caulk with a utility knife or razor blade.
The caulk was still perfect in the few areas i had caulked along the siding.
Siding caulk can be used on several different areas of your exterior siding to help prevent water damage and moisture buildup.
Pay special attention to siding located near the ground and at junctures where the siding meets other building materials.
For small holes make the opening in the tube no more than 60 to 70 percent of the width of the hole in the wood.
Think of a wood home as a living thing.
It may be possible to perform minor repairs and improve aesthetics by caulking and painting.
3 fit a caulking.
Next look for more subtle telltale signs of deterioration problems such as discoloration rusted nails.
Let the primer dry.