# Best caulk for Hardie Plank siding?



## Termite (Apr 13, 2008)

I believe they make a special caulk just for fiber cement now. 

1/8" gap at butt and trim joints.


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## buletbob (May 9, 2008)

Yes they do! its made by Tight-Bond Its called tight bond weathermaster caulk, it comes in 125 variety of matched colors. Excelant gap filling and will not slump into the gap. BOB


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## DangerMouse (Jul 17, 2008)

i'm curious too,---> How much expansion / contraction is going to take place with this siding? <--- and shouldn't there be flashing in there somewheres?......but what do i know? i'm just a cartoon mouse......

DM


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## Termite (Apr 13, 2008)

When installing any lap siding, it is always a good practice to "flash" behind each butt joint with a small piece of 15# felt. Same thing at the trim and the ends' joint.


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## Clutchcargo (Mar 31, 2007)

From my experience, there's minimal expansion/contraction with this product. I believe the specified gap is mainly so that you can get caulk between the planks.


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## mikey48 (Dec 6, 2007)

Per Hardi's instructions if you flash behind the joint you can butt them up. I still caulk them


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## Termite (Apr 13, 2008)

Yeah, I would never butt them tight. The flashing is the guarantee that if water gets in, it will be shed down. It would be insane to install any kind of lap siding without a tin shingle or building felt behind the joint. I look at the caulking as an added means of protection.


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