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HardiePlank HardieTrim - 1/8" gap?

3926 Views 2 Replies 3 Participants Last post by  advanced_energy
My carpenter is installing HardiePlank and HardieTrim for the first time in northeastern Pennsylvania.

At multiple places in the HardieTrim installation instructions, it says to leave a minimum 1/8" gap between the siding and trim (at corners, windows, all places where siding meets trim), then caulk. 1/8" is a relatively large gap. Given both the Trim and the Siding are cement and we're installing it in warm/hot summer weather, how much expansion could there be?

I called Hardie technical dept and they said that even if the trim and siding are both Hardie, the wood beneath (sheathing and studs walls) could still expand, and that's why you need the 1/8" gap.

We'd like to moderately press up the siding to the trim without the gap and caulk the joint. Any recommendations would be appreciated.

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Well the instructions say to leave a 1/8" gap...AND the tech from Hardie told you to leave a 1/8" gap.Are you going to wait till someone on the internet tells you that you can do what you want?Will that make you feel better?:laughing:
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you ONLY caulk hardie where it butts against trim and corners. do NOT caulk where the siding butts against siding.
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