Can I use lost head nails, as I want the fixings to be discreet?
We find that these do not always perform satisfactorily, as the cladding boards may want to move, and the lack of a head could mean that the fixing will be unable to restrain any cupping. In extreme cases, boards could pull away over the lost heads due to wind suction, or expansion of the timber due to an increase in moisture content. However, small head fixings can be used satisfactorily and will be less visible than roundhead fixings, this approach should not be used for soft timbers like Western red cedar or those prone to high levels of distortion.
If hidden fixings are desired, it may be feasible to fix the boards from the rear, using a panellised system, but again timbers prone to movement can pull away from the fixings. It is recommended that project-specific guidance is sought from an expert source.
TRADA does not recommend secret fixing with T&G profiles because of the risk of the tongue splitting.
For more detailed information about timber cladding, take a look at our book External Timber Cladding, a comprehensive guide to the design and specification of timber cladding.
We also provides a range of services for building designers and product manufacturers to assist with timber cladding queries, as well as training and cpd.
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