A mark parlee a general contractor in des moines iowa responds in my experience water that gets trapped against fiber cement sidingcan be absorbed by the material causing joints to swell and shrink during freeze thaw cycles.
Field joint on cement siding.
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Install the next piece so its end butts lightly against the first photo 7 inset.
However this detail may not be effective at sealing the ends allowing water to be absorbed and swell the board ends.
Hardie plank which this siding does not appear to be is the most prominent of the fiber cement siding products but there are other manufacturers as well certainteed etc.
Caulk is usually used with fiber cement siding to prevent water intrusion at the butt joints.
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.
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Some instructions permit caulking at primed and smooth siding presumably because the caulk cosmetic defect will be hidden by the finish paint job.
The product is a proprietary plastic 20 year uv rated sheet 4 ml thick that is basically a six by twelve post it note.
Gap where the end meets the corner board photo 7 inset and make sure the other end lands on a stud line.
Butt end joints should be installed with factory sealed or factory prefinished ends butted together in moderate contact.
In the last few years all manufacturers all that i know of at least have moved to strongly prefer or specifically demand that the field butt joints be flashed not.
Do not caulk fiber cement siding butt joints edges.
James hardie 8 25 in x 144 in hz10 hardieplank cedarmill fiber cement lap siding.
Hardiplank lap siding is a fantastic siding material that we ve been using for years on both residential and light commercial building projects.
Generally the manufacturers do not recommend caulking at factory painted fiber cement siding butt joints presumably because it creates a cosmetic defect.
Hardiplank lap siding field butt joint treatment.
Each sheet is pre cut with a stick it adhesive for the fastest application available.
Bearskin joint flashing is a plastic sheet for use as a joint flashing behind every butt joint in the siding.
It is never acceptable to leave a gap of any size at a butt end joint.
Measure and cut to length the first piece of siding and nail it in place photo 7.
Fiber cement siding accessories.