Caulking Hardiplank Lap Siding

Deterioration of the caulking in the joint has become a maintenance issue for home owners over time.

Caulking hardiplank lap siding.

This technical bulletin is an explanation supporting the announcement made by james hardie on september 8th 2008 withdrawing its recommendation on the use of caulk at field butt joints for hardieplank lap siding. Flashing acts as a waterproofing layer for this type of siding and caulking will prevent the flashing from doing its job. Osi quad product brochure. 25 4 mm on overlap no caulk figure 1.

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. Joint flashing is recommended for all hardie lap siding now. Apparently no one here read the technical bulletin 9 that james hardie released in 2008. Many professionals like those at james hardie also agree that you should not use caulk on fiber cement siding unless there is no metal flashing underneath.

Lastly james hardie does not allow the use of colour matched caulking for touch ups. Hardie no longer recommends the caulking of any joint in their lap siding colorplus or primed. Is the old caulking removed before new coats are applied. This video is about how to like a pro.

James hardie also does not recommend applying caulk to the horizontal overlap between siding planks see figure 2. 12 hardiplank james hardie warranty claims information tel. 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. 152 4 mm wide 1 in.

It will look okay on day one but caulk is not designed to be used as a touch up and it will weather at a different pace than the siding. The nails holding up the siding should not be caulked. A diyer or a novice painter might attempt to achieve a cleaner look by caulking the siding nails but the nail is guaranteed to push the caulking material out within a few months.