Technical Support / Technical Documents / Caulking Tips
Manufacturers' Caulk and Sealant Recommendation Sheet S-100B
Issued July 2000
General: James Hardie believes it is good building practice to seal the joints to prevent moisture, such as wind-driven rain and snow, from penetrating the wall cavity. Caulking around windows, doors, eaves and trim edges gives added insurance that leaks will not occur. 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.
Caulks and Sealants: James Hardie recommends the use of caulks and sealants that remain permanently flexible. Look for the words 'permanent flexibility' or 'permanently flexible' written on the label or in the accompanying literature. Allowing caulks to dry for the recommended time will help to prevent paint from flashing and/or cracking over the caulked joint.