Flashing Behind Hardie Board Siding

Water which makes it s way behind the hardie siding should hit the flashing layer.

Flashing behind hardie board siding.

There are several products that can be used in this type of application. James hardie recommends 6 inch wide flashing that overlaps the course below by 1 inch. Bearskin joint flashing is a plastic sheet for use as a joint flashing behind every butt joint in the siding. This has proven problematic over time as caulking the joint results in unsightly surface appearances due to the different textures as well as resulted in failure of the caulk joint and associated ongoing maintenance.

One of those recommendations deals with properly flashing behind field butt joints. Flashing behind butt joints is an effective low maintenance way to comply with building code and help protect against water intrusion. H jointer covers james hardie recommends 6 inch 152 4 mm wide joint flashing that overlaps the course below by 1 inch 25 4 mm. Each sheet is pre cut with a stick it adhesive for the fastest application available.

Flashing is a strip of metal usually aluminum about 8 inches long and bent at 90 degrees with each side at least 5 inches wide. As you can see in the photo above we ve installed a piece of flashing behind each field butt joint in order to keep water and moisture from getting behind the siding. Some local building codes may require different size flashing. This is a 6 wide piece of weather resistive material to make sure that no water gets through.

A common problem with cement board siding products and some other types of horizontal lap siding is that older installation guidelines called for caulking the joint instead of flashing the joint. However some local building codes may require different size flashing. Joint flashing material must be durable waterproof material that does not react with cement based products. The product is a proprietary plastic 20 year uv rated sheet 4 ml thick that is basically a six by twelve post it note.

The flashing keeps water off the sheathing and drains water properly which prevents water damage.