Standard FireCrunch is a water resistant product before sealed, in that it does not retain water if unsealed in warm weather it will release moisture.

This means that an “unsealed board will absorb some moisture in damp or wet areas” if left unsealed. You should not expect the board to hold it’s integrity if submerged in water or exposed to multiple wet/dry processes, before use, particularly without adequate MgO sealing.

Use special MgSO4 “vapour permeable Sealer” (See Recommended products). Klaas AquaCrunch S1. (Supplied by Firecrunch).

FireCrunch should not be left out in the rain before sealing /priming. MgSO4 Sealer (See Recommended products)

Because FireCrunch is a breathing permeable board it will hydrate when not sealed. However, if inadvertently left in the wet or in exterior weather, move it to a dry environment with separated sheets. FireCrunch will dry out quickly without swelling or warping and hold it’s strength integrity.

FireCrunch that has been installed externally and not pre sealed could crack at fixtures due to residual moisture in the board being removed in the drying process, especially when exposed to multiple wet/dry processes.

Best practice:

  • Store undercover on delivery to site before use. Do not attempt to paint if board wet
  • Allow to dry completely before sealing painting or rendering, hydroscopic level under 10%.
  • FireCrunch board called (Type FCA) is sold in 10mm K-Clad SE AND TE 10
  • For flooring, K-Floor 19mm TG Tongue and Groove
  • For exterior walls in a Bushfire K-Clad flat finish or K-Wall a timber appearance groove / weatherboard TS12 2700×1000 x12mm
  • In Decking 16mm K-Deck TG Decking Groove boards for exterior decking
  • 19mm TG 27000×600 is also used for bushfire roofing substrate eliminating expensive 15mm marine ply (which is actually combustible
    and does not now have a AS1530.1 certificate) So should NOW never be used in Bushfire areas ( NCC 2019 revisions) combustible material.

16mm FIreCrunch is designed for internal/external use so is the best choice for decking and external applications.

Pre-seal FireCrunch boards with MgO primer sealer Klaas S1 AquaCrunch. (See Recommended products)

And use Dulux Precision MAX adhesion undercoat and Dulux hard wearing decking paints, to choice of timber colour.