Protecting a Listed/Historic BuildingThe difficulty with this type of work is that you must balance alteration restrictions with the necessary changes to adequately protect the building from a different, more natural & unwanted 'alteration'.
Your local planning authority has a conservation officer who will know how best to handle this kind of balance, so it is definitely worth contacting them prior to carrying out work.
Protecting your Building from Radon Gas SeepageMany listed buildings in Bath have a basement; the danger from this is that there is a large surface area in contact with the soil; i.e. the walls of the basement provide radon gas entry points from the soil as well as the floor. The primary gas entry points are cracks in concrete, floor-to-wall joints (where the walls of the basement and the floor meet), porous building materials and mortar joints (where two walls meet).
The key to dealing with gas seepage in a historic/listed building is by installing edge located sumps or sub-floor vents. Internal sumps or ducts will likely require the floor to be taken up, which should always be avoided in a listed building. If this is the only option and the floor of your building is flagged, careful recording of the position and layout of each stone should be carried out prior to the installation of the sump or duct.
Radon SumpsA radon sump consists of an exhaust pipe from under the floor of your home for radon gas to escape through. It is the most effective way of reducing indoor radon levels and can be active or passive.
- Active radon sumps are powered by an electric fan to propel gas out of the exhaust pipe.
- Passive are not powered and are less effective, but they are sufficient for low radon levels.
An airbrick is perforated brick, with a grid of holes allowing air to flow through it. This can be an alternative to a radon sump when your building has a suspended floor; airbricks can be used to to allow air to flow beneath the floor.