Penetrating Gases ~ Methane and Radon

Methane methane is produced by deposited organic material decaying in the ground. It often occurs with carbon dioxide and traces of other gases to form a cocktail known as land fill gas. It has become an acute problem in recent years, as planning restrictions on green-field sites have forced development of derelict and reclaimed brown-field land.

The gas would normally escape to the atmosphere, but under a building it pressurizes until percolating through cracks, cavities and junctions with services. Being odourless, it is not easily detected until contacting a naked flame, then the result is devastating!

Radon ~ a naturally occurring colour/odourless gas produced by radioactive decay of radium. It originates in uranium deposits of granite subsoils as far apart as the south-west and north of England and the Grampian region of Scotland. Concentrations of radon are considerably increased if the building is constructed of granite masonry. The combination of radon gas and the tiny radioactive particles known as radon daughters are inhaled. In some people with several years exposure, research indicates a high correlation with cancer related illness and death.

Protection of buildings and the occupants from subterranean gases can be achieved by passive or active measures incorporated within the structure.

1. Passive protection consists of a complete airtight seal integrated within the ground floor and walls. A standard LDPE damp proof membrane of 0 3 mm thickness should be adequate if carefully sealed at joints, but thicknesses up to...