Reply To: New Home Moisture Issues

[Gleb Speranski]

Hi Phil,

Thanks for the photos. They are astonishing.
Here is my assessment of what is going on and recommendations:
1. The fact that the house is at the bottom of a hill suggests that there can be a very substantial moisture transport coming from underneath. I therefore agree with earlier comments re benefits of a ground vapour barrier.
2. Furthermore, the hit-n-miss battens around the perimeter are fitted with hardly any space in between. Hence the subfloor space qualifies as ‘fully enclosed’ and therefore needing a ground VB even more.
3. It is hard to see on the photo but the flooring appears to be a particle board. If it is, then it is highly hydroscopic (they did not nicknamed it ‘weatbix’ for nothing!) and therefore largely contributing to the moisture transport. After GVB is fitted the drying of the particle board may result in an unpleasant chemical smell that will stay for quite some time. Therefore it is a good idea to install GVP now so the house would be easy to air over summer months.
4. Polystyrene insulation under the floor does not reduce the water vapour transport.
5. Good heating is essential for a house like this. A heat pump is hot ideal due to low drying capacity and low heat output. A wood burner would be a much better option.
6. The house’ cladding appears to be a fibre cement board which is also a water absorbing material and could further contribute to the moisture issue.

Regards,
Gleb

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