Caulking Fiber Cement Siding

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.

Caulking fiber cement siding. Fiber cement boards are caulked only when there is no metal flashing behind them. A mark parlee a general contractor in des moines iowa responds. They re cheaper and easy to install and you can cut the proper size hole in a plastic mounting block with a utility knife or a snips. 2 house built before 2008 so has no flashing okay to caulk.

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. On our jobs we typically don t leave gaps for caulk at butt joints because this detail can contribute to the problem. Flashing acts as a. Instead we snug the joints up tight and.

Item 157140 model 11532. That is why we are showing you some other products for various surfaces along with our top pick. Natural siding boards are designed to expand and contract with the elements and we do not want any adhesive to prevent their natural movement. 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.

Big stretch acrylic latex caulking sealant by sashco. Dap alex plus 12 pack 10 1 oz white paintable latex caulk. The following information is adapted expanded a bit from certainteed corporations installation instructions for the company s fiber cement siding products as this is the most comprehensive guide we could find for caulking clearance instructions when installing fiber cement siding. Jaime prefers to use the vinyl mounting blocks typically used with vinyl siding.

In my experience water that gets trapped against fiber cement siding can be absorbed by the material causing joints to swell and shrink during freeze thaw cycles. Most fiber cement manufacturers make mounting blocks for lights electrical receptacles a c lines pvc venting etc. 1 i chose this caulk because it has 25 flexibility compared to silicone based caulk.