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Decking tolerances

This document outlines the inherent variations that are tolerated in both composite and wooden decking built by Acorn Construction Ltd. Due to the built-on-site nature of decking it is impossible to assure total uniformity of gaps, levels and edges. There can also be some variation in materials as they are sometimes prone to slight warping or other imperfections resulting from manufacturing. 

Although we always aim for complete uniformity there are times when this is not possible. This guide makes you aware of the tolerances that we find acceptable. Any variation within these tolerances will not be counted as faulty or defective workmanship.

Joint gaps

Joint gaps in decking are where one end of a decking plank touches the end of another plank. To allow for heat expansion, boards are usually left with a 1mm gap. The tolerance for this gap is up to 2mm at any point in the joint. 

Board gaps

As standard the gaps between boards are 6mm and are set in place using plastic fasteners. The tolerance on these gaps is 4mm meaning that the gap at any point between 2 boards can be between 4mm and 8mm. This tolerance is maintained regardless of fastening method unless specified otherwise. 

End gaps

The gaps between the end of a board and a flat surface are 6mm as standard with a tolerance of 4mm. This means they can be between 4mm and 8mm from the flat surface at any point in the gap. On angled or uneven surfaces this increases to a 6mm tolerance (3mm – 9mm gap).

Customer requested modifications

If a customer requests a gap different to the current 6mm gap this will be subject to a 6mm tolerance (+/- 3mm) unless the project manager specifies otherwise.

Requests for modifications must be made prior to payment of the initial deposit. Acorn Construction Ltd is under no obligation to make and changes after the quotation has been accepted.