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We are about to settle on this house and the pre-purchase inspection noted that the weatherboard cladding has not been installed all the way to the bottom of the wall (see pics). You can see that there is yellow tongue exposed. The area is undercover but we want to finish this.
The inspector suggested either beading or styrofoam spray could close this up easily.
Any suggestions on materials to use? Is breathability an issue to consider when closing up this gap (note: the house is raised on concrete stumps).
Many thanks in advance for your assistance 
Welcome to the Bunnings Workshop community @TyldenHouse. It's wonderful to have you join us, and many thanks for your question about a gap in cladding.
It looks like the weatherboards weren’t continued down to the timber deck because doing so likely would have breached building regulations. Cladding generally shouldn’t terminate at or below deck level as it creates a risk of moisture wicking up into the boards, which can lead to rot. In this case, it seems the deck stops very close to the wall—possibly even extending underneath the face of the weatherboards—which may explain the decision to leave a gap. Ideally, there should be a layer of sarking behind the cladding to prevent moisture from entering the home and to protect the exposed edge of the yellow tongue flooring. The visible yellow tongue is a concern though, as it’s not meant for exposure to the elements. This gap needs to be addressed not just for appearance but to ensure the home is weatherproof.
You’d be best to engage a builder to assess the situation properly and make sure any fix complies with building codes. They can check whether sarking was installed and, if necessary, extend it down to a more appropriate point. Using expanding foam to fill the void could be a quick solution, but it’s not usually intended for weatherproofing, so you’d also want to install a trim or beading to shield it from wind-driven rain. Something like a PVC trim would close it off neatly and provide a bit of added protection.
Please let me know if you have any questions.
Mitchell
Hi @TyldenHouse,
It would be the builder who would need to come up with a plan that complies with construction codes; that's what they specialise in. I would suggest that the lower boards need to be removed, the sarking repaired, and the boards reinstalled with a suitable trim at the bottom. However, you would need to speak with a builder to determine whether this is a possibility. It's one thing to seal the gap, but another entirely for that fix to comply with building codes.
They might be happy with a simpler solution, such as just filling the gap. If you only need to rectify the issue shown in the inspection report, and they will be happy if the repairs they've suggested are done, then you might want to go with the expanding foam and trim.
Mitchell
