What are the causes of raised grain on exterior facings and how should it be rectified?


An architect had an issue with raised grain on exterior facings. The facings had been used as part of an expensive reclad on a previously leaky home. While they were weathertight, the owner was unhappy with their appearance and demanded that the problem be rectified.


Raised grain is a machining fault caused by springback of compressed wood when its moisture content increases. The compression can be caused by blunt or improperly jointed planing knives.
To resolve it is best to leave the problem areas until after summer if possible, allowing the heat and summer humidity to allow full stress relief before sanding and then repainting.
Refer to the pages on Exterior Finishes on the NZ Wood website