Protection of Radon Barrier

Tifosi

Query on protecting Radon barrier during construction.

Proposing to pump in the screed floors after weather tight.

Current detail 1 shows Radon barrier on top of structural floor,so will be unprotected

Proposing to install Radon barrier on top of hardcore, sand binding layer and structural floor Detail 2, hopefully to protect the barrier during construction.

Would this be the norm when pumping the screed in at latter stage.

Metric Tensor

Nothing wrong with your proposal - in houses with raft foundations it's often completely below the concrete pour.

Don't forget that you need a minimum of 200mm of T2 perm below the radon barrier. "Compacted Hardcore" isn't a sufficient specification.

Tifosi

Metric Tensor wrote: »

Nothing wrong with your proposal - in houses with raft foundations it's often completely below the concrete pour.

Don't forget that you need a minimum of 200mm of T2 perm below the radon barrier. "Compacted Hardcore" isn't a sufficient specification.

Metric thanks

Discussed with a screed contractor, one option mentioned was to install the T2 permeable hardcore, installed the radon on the internal, external block but leave 6 inch or so on the internal. Complete house to weather tight, then install the Radon barrier on top of the T2 as normal and tape and dress to the previous installed flap. then insulation, UFH, screed etc.

Will review options further.

Calahonda52

Tifosi wrote: »

Metric thanks

Discussed with a screed contractor, one option mentioned was to install the T2 permeable hardcore, installed the radon on the internal, external block but leave 6 inch or so on the internal. Complete house to weather tight, then install the Radon barrier on top of the T2 as normal and tape and dress to the previous installed flap. then insulation, UFH, screed etc.

Will review options further.

A lot of taping involved with this idea, as far as i know you can't get single sided radon approved tape so arseing around at the corners will be madra

See attached as per MT's comment, ignore its not red

Tifosi

Yes I am not fully confident of taping, or welding various membranes together, too many things could go wrong.

Preference would be a continuous membrane throughout, less risk.

There could be approximately 250mm-300mm exposed on the vertical on the inside wall during the build until the insulation and screed go down so would be worried that this could de damaged, or will be damaged. So will review how this can be protected.

Metric Tensor

Also bear in mind that there are different membranes with different tensile strengths. Some are a lot more robust than others.

I'm not sure if I'm allowed mention a specific product but we use Monarflex RMB400. It's reinforced and stronger than most membranes. It's still not bullet proof but is definitely harder to tear.

Mods: Please delete if I've overstepped and I can PM product name to anyone interested.

Tifosi

Metric

Great thanks, thats what I was looking at, also read up on the T2 4/40mm I think SR14 so good catch.

Probably give that a bash, pushing against the builder is delaying in installing the insulation, UFH and screed until weather tight so just need to be armed accordingly.

Tifosi

Related to this, just back from site a couple of items.

1.If I install the radon barrier then the structural floor as I would like( so no insulation, UFH, screed, until weathertight) when it rains there is potential it fills up with water. Where does this water go, or how is it remove.

2. If I install the floor the traditional Irish way, as all other houses, builder quote, and it rains where does the water go. Well as I understand through the internal block wall, through the perimeter vertical insulation, then probably down to the horizontal insulation.

3. I have read a well know insulation companies NSAI agrement and the UK BBA equivalent all reads similar until, " to limit risk of damage from condensation and other sources of dampness, the products, overlays should only be laid after construction is made substantially weathertight". The said company couldn't really answer why the difference, more importantly warranty on the product in Ireland if install the "traditional" way, and it gets wet, which is more then likely.

Grateful to know others experience in this regard.

dfader

Tifosi wrote: »

Query on protecting Radon barrier during construction.

Proposing to pump in the screed floors after weather tight.

Current detail 1 shows Radon barrier on top of structural floor,so will be unprotected

Proposing to install Radon barrier on top of hardcore, sand binding layer and structural floor Detail 2, hopefully to protect the barrier during construction.

Would this be the norm when pumping the screed in at latter stage.

Radon barrier is often brought through the rising wall at top of subfloor. Then normally 225mm layer of dpc between dpc in blockwork at finished floor level down to radon barrier. The floor is poured immediately on completion of barrier meaning no damage. The subfloor being poured immediately after radon barrier finished, so you need a couple of dry days so water does not pond on the radon barrier. If you leave the radon barrier exposed as in the detail it will get damaged. Also you and your architect need a detail for internal walls. There is an alternative detail that will allow the subfloor be poured right through and protect your barrier for those too.

Tifosi

The proposal is detail 2 , so I would have thought the the radon barrier would be protected with the exception of the vertical elements for approximately 275mm.

dfader

Tifosi wrote: »

The proposal is detail 2 , so I would have thought the the radon barrier would be protected with the exception of the vertical elements for approximately 275mm.

That's right, the vertical 275mm part will get ripped by the follow on trades.