Caulking Cement Fiber Siding

Caulk is usually used with fiber cement siding to prevent water intrusion at the butt joints.

Caulking cement fiber siding.

Fiber cement boards are caulked only when there is no metal flashing behind them. Many professionals like those at james hardie also agree that you should not use caulk on fiber cement siding unless there is no metal flashing underneath. What you want to use is a silicone caulk because it s the most permanent one. 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.

But you are correct that it is very difficult to paint. We organize include fiber cement siding gap repair advice from the manufacturer as well as from builders and building inspectors. It s got good adhesion and expands and contracts. Butt joints however should be nailed tightly together and should not be caulked.

Fiber cement boards don t expand and contract much but leave a little room for expansion at the end joints and then fill the gap with caulk. We only caulk butt joints on cedar siding if previously caulked. Natural siding boards are designed to expand and contract with the elements and we do not want any adhesive to prevent their natural movement. We provide a table of all fiber cement siding installation clearance or gap specifications caulking requirements storage or moisture requirements.

Flashing acts as a waterproofing layer for this type of siding and caulking will prevent the flashing from doing its job. However this detail may not be effective at sealing the ends allowing water to be absorbed and swell the board ends. 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. Best caulk for fiber cement siding or hardiplank siding lets you have the perfect sealing your surface needs.