Re-Cladding: The Design Implications of Moisture Damage to Timber Frames


Company: ARIDON®

The Golden Rule: Where there is Black – cut it back!! One of our ARIDON® installation teams have recently been focused on re-cladding & renovating leaky building projects, of which the last two had multiple causes of moisture damage. We uncovered, external moisture damage through walls and roof, interstitial condensation damage and a leaky water pump – the net result a re-clad that went from a quick fix to a major re-build.

Why – because we saw small patches of black on the exterior face of the timber and the first reaction was “good – it is not that bad”. Fortunately for the owner, ARIDON® organised an expert in moisture management and leaky homes to provide independent consultation. He advised the builders to remove the blackened timber. What was found behind the stud was an explosion of black mould and decay (not visible from the exterior surface). The net result – complete replacement of the frame in those areas, redesign of the roof wall junctions, and tracking the moisture issues back into the roof where interstitial condensation had begun to cause rot in the ceiling. This extension was only 15 years old and a complete design and build failure.

The key learning from this re-clad is that what shows up on the face of the timber (e.g. light discolouration) can hide something very sinister behind it. As our expert pointed out – he is now visiting projects which have had 2 attempts already to resolve leak and mould issues but the problem has re-occurred because the framing had not been properly addressed in the first instance. The reasons behind this are varied but generally are as a result of inadequate knowledge on the part of some carrying out the remediation work.

How does this affect you as an Architect and Designer? Recladding/designing an existing structure will rejuvenate the building – however if the builder doesn’t pick up the structural defects, it could come back and damage your reputation. In addition, the best and only treatment of rotten or blackened timber is to remove it. Efficient removal of that timber often leads to doubling studs and other additional framing to put back the strength lost. This results in far less room for traditional cavity insulation approaches to the point where building code requirements of H1 and E3 may not be met.

What’s the Solution? ARIDON® SMART WALL. This system wraps the building frame in a thermal weatherproof shell. This ensures that:

  1. Moisture from the outside doesn’t penetrate the framing and dry zone of the building.
  2. Interstitial condensation will not form in the wall cavities because a dew point will not form in the framing cavity
  3. The insulation is continuous and well exceeds building code requirements no matter what framing ends up being installed
  4. Temporary weatherproofing to the build as soon as the windows are back in
  5. The weatherproofing and insulation system is installed by a team that is experienced
  6. in re-clads, with a product that is designed to combat leaky homes.

The ARIDON® SMART WALL system is fully BRANZ appraised and replaces the need for building wrap, rigid air barriers, cavity battens, insulation and internal moisture management layers. We offer the complete system – fully installed and warrantied by ARIDON Ltd, with a team of structural engineers and draughtsman on hand to answer any technical detailing questions and provide a comprehensive suite of technical details to simplify the specification process.

Suitable for commercial and residential construction – with no restriction on claddings.


Ask ARIDON®| 0800 ARIDON (274 366) | |


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