Caulking Lap Siding Bottom Edge

Water is meant to exit through the bottom of each board.

Caulking lap siding bottom edge.

While paint does tend to somewhat glue these pieces together caulking them is never advised and can cause permanent damage. Lp siding products also come in sheets in when water runs down the face of the siding it tends to hang on the bottom edge wicking up and causing the bottom edges to swell and delaminate. The worst failure we have seen yet. How to caulk the window trim on lap siding 1.

Pull the tip of the caulk tube slowly along the joint of the window trim and the siding holding the caulk gun at a. 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. If overused or incorrectly placed siding caulk can cause more damage to your exterior than good. Also avoid caulking tongue and groove siding boards together.

If you prefer to caulk before painting you should still paint the cut ends first. Wherever hardie siding meets a trim board the company recommends you leave a 1 8 gap between the siding and the trim and apply a 3 8 bead of approved caulking to protect and seal the edge of the siding. After the paint dries apply caulk and then paint the rest of the siding. The bottom edge of lp lap siding is where the failure is first evident.

It needs to move and breathe. Think of a wood home as a living thing. Bottom of siding boards should not be caulked. Lp recommends applying primer the foundation of the house before painting the siding to prevent moisture from wicking into the siding.

The siding expands and contracts with temperature and humidity.