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.
Caulking pressboard siding.
Siding caulk can be used on several different areas of your exterior siding to help prevent water damage and moisture buildup.
It may be possible to perform minor repairs and improve aesthetics by caulking and painting.
The siding expands and contracts with temperature and humidity.
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.
The thing is over time the chemical treatment in the pressure treated wood dries out and the wood contracts and literally gets a tiny bit smaller since it s not now swollen with moisture.
Let the primer dry.
Brush or roll a layer of exterior primer on the flat portions of the masonite siding and use the tip of a paintbrush to work the primer into seams and crevices.
Next look for more subtle telltale signs of deterioration problems such as discoloration rusted nails.
Trim the tip of the tube of caulk with a utility knife or razor blade.
Watch this graphic depiction of the removal and replacement of hardboard siding.
Think of a wood home as a living thing.
Also avoid caulking tongue and groove siding boards together.
However once water has penetrated hardboard siding and deterioration has begun the siding will eventually need to be replaced.
3 fit a caulking.
The caulk was still perfect in the few areas i had caulked along the siding.
Pay special attention to siding located near the ground and at junctures where the siding meets other building materials.
Water is meant to exit through the bottom of each board.
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.
While paint does tend to somewhat glue these pieces together caulking them is never advised and can cause permanent damage.