Caulking Between Siding Boards

James hardie recommends the use of caulks and sealants that remain permanently flexible.

Caulking between siding boards.

Caulking them is a mistake and the caulking is likely to fail prematurely. Vertical trim gap caulking. When james hardie siding products butt into wood based materials a 1 8 gap will allow for expansion and contraction of the wood based product. Seal a door frame in place and seal the subfloor at the bottom of a door frame.

Fill in gaps between crown moulding and baseboards. These siding joints can be caulked successfully if the gap is wide enough for the caulk to get into the crack. While paint does tend to somewhat glue these pieces together caulking them is never advised and can cause permanent damage. Flashing acts as a waterproofing layer for this type of siding and caulking will prevent the flashing from doing its job.

Another critical place is where the siding butts together in the middle of the wall. Always caulk between the siding and the trim. 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. Think of a wood home as a living thing.

If the siding joint is so tight that the caulk only bridges the gap it may split. Also where the siding meets corner boards and corner board joints. Do not caulk between siding and any built in receiving channels located at or around windows. It needs to move and breathe.

The siding expands and contracts with temperature and humidity. Use latex painter s caulk inside of doors and windows or to quickly fill cracks. The hypothesis that if it is properly sealed with caulk no moisture will get behind the boards has not only been proven wrong by building scientists it s dangerous and could lead to problems such as sick building syndrome and mold. Best for use with drywall wood and masonry.

Placing caulk over large portions of wood siding prohibits the natural movement of the wooden panels and can cause extensive damage to the exterior of your home. Sometimes known as acrylic latex caulk.