UNDERGROUND HOUSE STAYS DRY THROUGHOUT THE FLOODS
31/01/2008
Going underground is an option considered by an increasing number of people as space becomes at a premium. Basements are a good alternative when extending out or up is not a solution.
Creating a watertight structure is essential. Concrete is porous when left untreated so experienced contractors will use PUDLO, a waterproof admixture for concrete, to create a structure that with good building practice will be fully watertight and guaranteed for 20 years.
Groundworks is a specialised area and it is important to get it right. PUDLO, a division of David Ball Group plc, provides extensive advice and support for architects, consulting engineers, contractors and ground workers involved in the construction of basement structures.
Tim Bawtree comments: "When our contractor left the project half way through the build the guys from PUDLO stepped in and ensured that the house was fully watertight within 24 hours of my call. The service was fantastic. Even with the worst flooding ever experienced in Cheltenham the house has been completely dry."
PUDLO has been widely used around the world for over 100 years and it is has been selected on projects such as the channel tunnel for its proven track record. PUDLO is available in bags and simply added to the ready-mix concrete at the batching plant prior to delivery to site.
PUDLO is both hydrophobic and pore blocking, and additionally alters the microstructure of the concrete, resulting in increased concrete density. This stops the water moving through the concrete and increases its compressive strength and chemical resistance properties.
An emerging trend as a modern method of construction, is to use an insulated polystyrene formwork system for concrete structures such as the PolySteel System used in the underground house. In these situations, the concrete is poured into the form and this remains permanently in place providing additional insulation for the building.
What was not fully appreciated on the Cheltenham house, is that an insulated polystyrene system can absorb the vibrations from the compactor, leaving air bubbles in the under compacted concrete. This can create a honeycomb effect when the concrete is cured and as a result water is able to pass through these voids. For this reason, and to remove the risk of under compaction, it is now strongly recommended that self compacting concrete is used for insulated polystyrene formwork systems below ground and there is a version of PUDLO specially designed for this purpose.