Caulking Siding Joints

Generally we do not recommend caulking butt joints on cedar siding.

Caulking siding joints.

Where two pieces of siding meet. There s no way around regular maintenance of those siding butt joints unless you want to completely remove the siding and install joint flashing. Although i do not understand why they have not changed the information about caulking in the instruction manual. If the siding joint is so tight that the caulk only bridges the gap it may split again.

Joint flashing is recommended for all hardie lap siding now. These siding joints can be caulked successfully if the gap is wide enough for the caulk to get into the crack. Apply these strips in place of traditional caulk or over already caulked joints for a finished appearance. The answer depends on the manufacturer and installation method used when the siding was first installed.

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. Caulk backer rods are lengths of foam that help fill large gaps before caulking. 25 4 mm on overlap no caulk figure 1. It is generally not a good idea to use caulking on wood siding.

Those joints need to be protected somehow. While as a diyer you might be obsessing about your caulking skill truth be told that will not matter if you don t have the right caulk. Joint flashing butt joint horizontal lap treatment june 2014 james hardie does not recommend caulking butt joints or the horizontal overlaps joint flashing 6 in. Caulking around windows doors eaves and trim edges gives added insurance that leaks will not occur.

James hardie also does not recommend applying caulk to the horizontal overlap between siding planks see figure 2. Sometimes the old caulk in the siding joint is cracked and you need to cut the old caulk out with a razor knife. Natural siding boards are designed to expand and contract. Deterioration of the caulking in the joint has become a maintenance issue for home owners over time.

Butt joints but not all butt joints. 152 4 mm wide 1 in. If overused or incorrectly placed siding caulk can cause more damage to your exterior than good. Similar to weatherstripping caulk strips are pre shaped rolls of sealant that have a peel and stick installation.