Buying in low risk Radon affected area (New build)

weeg

If the Site investigation report states it as a risk then the developer will have installed protective measures. (And this is something that Building Control generally check for). Mostly this is a heavier duty sheeting than the standard damp proofing membrane, along with vent under the slab as required.

Long story short: Assuming your building wasn't a complete cowboy, it isn't an issue.

Source: 5 years designing foundations and substructures for new build housing

GDB2222

weeg said:

If the Site investigation report states it as a risk then the developer will have installed protective measures. (And this is something that Building Control generally check for). Mostly this is a heavier duty sheeting than the standard damp proofing membrane, along with vent under the slab as required.

Long story short: Assuming your building wasn't a complete cowboy, it isn't an issue.

Source: 5 years designing foundations and substructures for new build housing

I’m intrigued now! How do you vent under the slab? It can’t be easy, as it is a big lump of concrete resting on the ground. Also radon is heavier than air, so do you need some sort of mechanical ventilation?  

weeg

It is actually easy! You use a single sized gravel layer under the slab (then sheeting and sand for blinding the concrete as required), along with vents that allow for airflow through the gravel, which works to prevent potential build up of any pockets of radon. But really the crucial step is sealing the slab and popups so that any radon stays underneath the slab out of the building. If it was a very high radon then you add in a network of pipework with top vents, a sump and a mechanical ventilator.

GDB2222

Thanks for explaining.