Damp courses
Filed under Damp and Mould, Ventilation and Air Quality, Ground Moisture.
May 10th, 2009
What’s the minimum depth for a damp course? My 80 year old house has been repiled in the past and sits on concrete piles. The majority of the outside walls are not in contact with the ground but the back wall is in contact with the outside concrete path. I’m worried that the back of the house could be damp. How far above the path should the inside floor be? And what can I use to prevent draughts under house on the other 3 sides – can it simply be boxed in or do I need a professional damp course installed?
editor, May 10th, 2009 on 10:34 pm
Hi there and thank you for your post.
With regard to the height of the floor, the guidelines are for the interior floor level to be at least 225mm above ground level (see page 15,
http://www.dbh.govt.nz/UserFiles/File/Building/Determinations/2008/pdf/2008-35.pdf).
With regard to whether you need a damp course and what should be done, I recommend that you seek professional advice from a competent builder regarding both this and the provision of adequate (but not excessive ventilation) under the house. The Master Builders Association can provide a list of their members working in your area (see http://www.masterbuilder.org.nz/).
Once you have addressed these issues you could consider additional energy efficiency measures such as a polythene vapour barrier under the house and/or underfloor insulation to help keep the indoor environment warmer and healthier. You may be entitled to some financial assistance for the polythene moisture barrier and underfloor insulation under the EECA EnergyWise programme (see http://www.eeca.govt.nz for additional information).
I hope this advice will be of some assistance. However, please do feel free to contact one of our energy advisors on 0800 388 588 if you would like to discuss anything further.
Regards,
Sarah Free (energy advisor, Wellington HEAC)