Cement Board Siding Seams

Buckled fiber cement siding is most likely to occur because the installer failed to give the recommended gap between the ends of the fiber cement boards and abutting vertical trim at corners windows doors etc.

Cement board siding seams.

A common problem with cement board siding products and some other types of horizontal lap siding is that older installation guidelines called for caulking the joint instead of flashing the joint. It is a very simple process and i used some fibatape and thinset mortar to seal the cement board j. Pretty much all trim joints need to be sealed. This has proven problematic over time as caulking the joint results in unsightly surface appearances due to the different textures as well as resulted in failure of the caulk joint and associated ongoing maintenance.

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. Manufacturers caulk and sealant recommendation sheet s 100b issued july 2000 application. Fiber cement siding accessories. Trim boards wood windows.

We can see a hard dried layer of caulk that was a bit under 1 8 inch wide inside of the now wide open butt joint between two siding boards. James hardie 8 25 in x 144 in hz10 hardieplank cedarmill fiber cement lap siding. In this video i show you how to tape cement board joints. Some manufacturers do not require the metal flashing therefore we caulk the butt joint to keep the pieces together and also prevent moisture.

It s available in a variety of sizes and shapes to match many of the old siding shingles installed over the last 60 years. Fiber cement boards are caulked only when there is no metal flashing behind them. Weatherside fiber cement siding is the 1 and weatherside fiber cement siding is the 1 and only solution for replacing or repairing old asbestos siding shingles. Our siding close up photo at page top illustrates what may be another clue in the history of a failed installation.

We only caulk butt joints on cedar siding if previously caulked. For pricing and availability. It does nothing else but produce fiber cement siding and cement backer boards. Traditionally board and batten siding starts with wide vertical planks boards which are then joined together by thin vertical strips battens to cover the seams.

This article series includes field reports of fiber cement board lap siding butt joint gap.