Radon protection
What radon is
Section titled “What radon is”A naturally occurring radioactive noble gas produced by the decay of uranium in the ground, which flows from the ground through the structure into the interior.
Outside it disperses and dilutes; in an enclosed interior it can build up, especially on the levels in contact with the ground — basements and ground floors.
Why it has come to the fore
Section titled “Why it has come to the fore”For two reasons:
- Buildings have become more airtight. In old, draughty buildings the rising gas was continuously exchanged; in a well-sealed modern building it is not.
- Understanding has grown that long-term exposure is a health risk.
How it gets in
Section titled “How it gets in”Through the gaps in the structures in contact with the ground: cracks, penetrations, the junctions of the floor construction, pits, pipe penetrations.
The driving force is often the building itself: the internal pressure and temperature difference “draws” air from the ground.
The elements of protection
Section titled “The elements of protection”Airtight separation
Section titled “Airtight separation”A continuous, sealed closure of the structure towards the ground: continuity of the membrane, sealing of the penetrations.
This is the same detail that protects against ground moisture — the two tasks can be solved together. Protection against ground moisture.
Ventilation beneath the floor
Section titled “Ventilation beneath the floor”Where there is a suspended floor — with ground screws, for example — ventilating the void beneath it carries the rising gas away before it reaches the structure.
That is one of the non-obvious advantages of the light gauge steel, raised-floor solution.
Active extraction
Section titled “Active extraction”Where necessary, extraction can be formed from the layer beneath the slab. It can be retrofitted, but it is cheaper designed in.
Measurement
Section titled “Measurement”The risk is shown by measurement, carried out in the finished building with a long-duration detector.
When to deal with it
Section titled “When to deal with it”At design stage, because the basis of the protection is the structural detail. Intervening afterwards — though possible — is always more expensive and more limited.
The point
Section titled “The point”Radon protection depends on the same junction as moisture protection: a continuous closure of the structure towards the ground. Get that right and you solve two problems at once.