Caulking For Fiber Cement Siding

Install the next piece so its end butts lightly against the first photo 7 inset.

Caulking for fiber cement siding.

It s got good adhesion and expands and contracts. What you want to use is a silicone caulk because it s the most permanent one. Applying caulk to the butt joint is ineffective because the gap is not large enough to accommodate the sealant. 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. Caulking around windows doors eaves and trim edges gives added insurance that leaks will not occur. Do not caulk fiber cement butt joints edges. A mark parlee a general contractor in des moines iowa responds in my experience water that gets trapped against fiber cement sidingcan be absorbed by the material causing joints to swell and shrink during freeze thaw cycles.

Flashing acts as a waterproofing layer for this type of siding and caulking will prevent the flashing from doing its job. 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. Trim boards wood windows. Gap where the end meets the corner board photo 7 inset and make sure the other end lands on a stud line.

The specification to omit caulk at siding butt joints is for new installations and is discussed in detail by the manufacturer. Some manufacturers do not require the metal flashing therefore we caulk the butt joint to keep the pieces together and also prevent moisture. Caulk is not to be installed in j channel f channel nor in fiber cement siding butt joints though it may have been applied later by a homeowner or maintenance contractor. Measure and cut to length the first piece of siding and nail it in place photo 7.

We only caulk butt joints on cedar siding if previously caulked. 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. Check the caulking specifications provided in the installation guide by the manufacturer for your specific siding product. However this detail may not be effective at sealing the ends allowing water to be absorbed and swell the board ends.