Caulking Lap Siding Bottom Edge

Think of a wood home as a living thing.

Caulking lap siding bottom edge.

Scrape the side of the window trim next to the siding and the immediate edge of the lap siding with a paint scraper. 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. 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. When deciding how to use caulk on your siding however it is generally more important to consider where you should not use it.

Lp recommends applying primer the foundation of the house before painting the siding to prevent moisture from wicking into the siding. The worst failure we have seen yet. While paint does tend to somewhat glue these pieces together caulking them is never advised and can cause permanent damage. How to caulk the window trim on lap siding 1.

Water is meant to exit through the bottom of each board. If overused or incorrectly placed siding caulk can cause more damage to your exterior than good. 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. Bottom of siding boards should not be caulked.

It is generally not a good idea to use caulking on wood siding. The siding expands and contracts with temperature and humidity. Also avoid caulking tongue and groove siding boards together. If you prefer to caulk before painting you should still paint the cut ends first.

The bottom edge of lp lap siding is where the failure is first evident.