Caulking James Hardie Siding Facts You May Not Know

HardiePlank fibre-cement lap siding is a tinted product available in a range of colours, or as plain. The joints between the boards do not require sealing when set horizontally and with a correct overlap. The principle is the same as roof tiles, shingles and slate. Water flows naturally downwards, although we do always install a waterproof barrier behind that doubles as insulation.


Installing HardiePlank Lap Siding Correctly


We can lay the lengths over braced wood or steel studs. As mentioned, this is sufficiently moisture resistant even in driving rain, and should be wind resistant when adequately attached. However, a different treatment is necessary where the product interfaces with the rest of the building:

# Corners must have adequate caulking with proprietary James Hardie sealant

# The same applies when a run of planks abuts doors, windows, eaves, and trim edges

# Where these interfaces are with wood, caulking should be over a 1/8″ gap

# However, Hardie recommends conventional flashing above door and window frames

# James Hardie also recommends all caulks and sealants are permanently flexible

# Caulks and sealants must not be covered or painted before the recommended time

HardiePlank strips are best nailed on through pre-drilled holes under the overlap. The company does not recommend caulking over ColorPlus products for aesthetic reasons.


Things to Take Note Of During a James Hardie Siding Installation


James Hardie fibre-cement products are quality materials when correctly applied. However ‘the devil is in the detail’ when it comes to sealing the edges.

# Is the caulk colour-matched to the siding colour?

# Is there an 1/8″ gap between the siding and timber for expansion?

# ColorPlus field joints must not be caulked for aesthetic reasons

# The contractor should not tool the fresh caulking to smooth it down

# Caulk should never substitute for flashing over windows and door frames

# All surfaces should be thoroughly clean before applying caulking

# Is the contractor correctly applying the caulking from the top down?

Use a Competent Contractor For New Siding


HardiePlank siding is not cheap; however the product is durable, and maintenance costs are relatively low. But the problems start when the caulking fails, and sections must be removed to fix problems. Repaired siding is never as good as a quality job by Valiant Exteriors Ltd.

Please visit our portfolio. Discover the difference, and why we are Calgary’s preferred siding, fascia, eaves-trough gutter, and soffit installers. Then call 403 829 1661 for a site inspection and a competitive quote.

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