Much of Christchurch is built on a swamp. Water can rise through the soil to create damp ground and in many places the water table is very close to the ground surface. While there are many sources of moisture within the home, up to 40litres of water can enter the home from the ground every 24hrs by means of water vapour transmission (rising damp). For houses with timber suspended floors this excess moisture can result in mould & fungus growth, condensation, dust mites, reduced heating efficiency and health risks.

While we continue to insulate ceilings, walls and windows, the household environment can actually worsen as moisture rising from the ground will become trapped and unable to evaporate to the outside.

Thus, the importance of starting at the bottom; SEAL THE GROUND FIRST!

The benefits of sealing the ground with Foamcrete are immediately obvious:

• There is significantly less moisture in the house, which means less condensation and a healthier atmosphere.
• Drier sub floor timber framing has a higher insulation performance and will last longer.
• The temperature of the space under the floor increases which means the rate of heat loss through the floor decreases because the temperature difference across the floor has reduced.
• Less energy is needed to heat the home for the same level of thermal comfort.

Canterbury Foam Concrete Ltd has been installing Foamcrete under houses since 1997 and the process is quite simple. Foamcrete is free–flowing and easy to pump into confined areas such as the cavity beneath a wooden floor through foundation vents. Because Foamcrete is self–levelling it flows over the ground, surrounding piles and into corners, sealing against the foundations and creating a barrier against rising damp. Foamcrete can usually be installed under most houses even when there is insufficient space to crawl.

In 2005 Canterbury Foam Concrete Ltd commissioned BRANZ Ltd (an independent and unbiased research, testing, consultancy and information resource for the New Zealand building and construction industry) to do an in–depth study to determine if covering the ground with Foamcrete could reduce relative humidity (i.e. moisture) in the house.

After completing the field trial, BRANZ Ltd determined that covering the ground with Foamcrete complies with the NZ Building Code External Moisture Clause E2, and is as effective as covering the ground with polythene.