Radon Barrier Query

Claremorrisdub · 25-06-2019 10:20am #1

Hi All,

i am looking at purchasing a house in Claremorris and have some queries which i am hoping the boards hive mind might be able to help me with. the development is in Hill crest, Claremorris, Co Mayo. i am trying to source information on whether a radon barrier has been fitted here. the estate was built in 2005.

I have spoken to the estate agent, and he has advised me that the developer has told him that they were fitted. he also showed me where the radon sump was out the back. the issue is, my engineer, who i got to come down from Dublin, says he cannot be sure this is the radon sump as it is not a black cover and does not say radon on it. the Estate agent advised me that he has checked another development which have Radon barriers fitted and he has advised they are the same colour also (clay coloured plastic as opposed to black), and Radon is not written on them. From the looks of it, i cannot see what else this could be, as there is nothing else near, and it does not look like an access panel for the drainage(cap is completely sealed, doesnt have screws that you could take off). i cant post a pick am new user so have to post 5 things first :-).

the other flag for me was that there is nothing referencing radon in the documentation i have received on the house, and it also references building regs compliance from 1990, when this came in in 1997. but having been built in 2005, i would have assumed they would be required by law to put it in and comply? so long story short, i have a few questions as this is a fantastic house, that i really want now. i would also be really surprised if this never came up on any of the other houses, its a 37 house development, so not like its a house on its own in the countryside.

is there a way for me to check somewhere if this development has the Radon barriers fitted?

if not, and i purchase the house, do a radon test, and its high, what are we talking ballpark for remediation( I'm hearing 2-3 k?)

Radon Shmadon, don't worry about it? everyone else in the estate is happy enough? am i blowing it out of proportion? i know the west is a high radon area, but if the house was built pre 1997, i wouldnt have a barrier anyway?

thanks in advance.

_Brian · 25-06-2019 10:30am

Having seen many, many barriers destroyed during building I wouldn’t let it stop me.
If your particularly worried you can get the testers and see how the actual radon level is which is really what is important.

I know contractors that were cutting radon barrier into strips and laying it over walls to appear like it was done. Equally I’ve seen lads laying insulation sheets use shovels to pierce the barrier to drain water down to stop sheets floating.

You could get a cctv survey of the suggested radon sump to see exactly what it is.

Squall Leonhart · 25-06-2019 10:35am

Evidence of a radon sump installed is not evidence of a barrier installed. The sump will be useless if there's been no radon membrane put down, gas won't collect in sump, but rather rise through the floors.

But like _Brian said, get a test done in the home if you're concerned.

FFred · 25-06-2019 10:48am

_Brian wrote: »

Having seen many, many barriers destroyed during building I wouldn’t let it stop me.
If your particularly worried you can get the testers and see how the actual radon level is which is really what is important.

I know contractors that were cutting radon barrier into strips and laying it over walls to appear like it was done. Equally I’ve seen lads laying insulation sheets use shovels to pierce the barrier to drain water down to stop sheets floating.

You could get a cctv survey of the suggested radon sump to see exactly what it is.

True. It’s rare that the full integrity of the barrier is not compromised by at least one of the trades unfortunately.

Claremorrisdub · 25-06-2019 11:11am

_Brian wrote: »

Having seen many, many barriers destroyed during building I wouldn’t let it stop me.
If your particularly worried you can get the testers and see how the actual radon level is which is really what is important.

I know contractors that were cutting radon barrier into strips and laying it over walls to appear like it was done. Equally I’ve seen lads laying insulation sheets use shovels to pierce the barrier to drain water down to stop sheets floating.

You could get a cctv survey of the suggested radon sump to see exactly what it is.

thanks a mill for the quick reply, so consensus is dont let it stop the purchase,go ahead and then test ? i think a proper test takes 3 months(leaving sensors there etc). its just turned into such a big thing in my head that i thought i would get some impartial advice. also, what am i looking at if its high after a test for remediation, we talking around 3 K?

mickdw · 25-06-2019 11:26pm

It is rare imo to see a properly marked radon cap at path.
If there is a capped off pipe sitting at path level out the back, it's very likely that sump and barrier has been installed. To what standard is another question!

A camera survey would give an answer as to whether the pipe leads to a sump or not.
I'd imagine if sump is present and even if barrier was defective, an negative pressure system would be cheaper to fit to that existing pipework that having to install from scratch.

Claremorrisdub · 26-06-2019 12:21pm

what would be the cost if worst case scenario, nothing there at all do you know?

Count Mondego · 26-06-2019 11:31pm

I put down the foundation of my house a year ago and took great care with the radon barrier. Between the jigs and reels and laying in the cages, I had around 200 holes to patch, and i paid for heavy duty barrier. I doubt many builders or contractors would bother with it.

I think the radon detectors need to be in place for a few months for an accurate reading. Check online to see if you're in a high radon area, if not forgot about it.

Calahonda52 · 27-06-2019 7:51am

Count Mondego wrote: »

I put down the foundation of my house a year ago and took great care with the radon barrier. Between the jigs and reels and laying in the cages, I had around 200 holes to patch, and i paid for heavy duty barrier. I doubt many builders or contractors would bother with it.

I think the radon detectors need to be in place for a few months for an accurate reading. Check online to see if you're in a high radon area, if not forgot about it.

The radon map is based on a few samples in each area so its possible to have it missed so best to do a 3 month test.

I have seen the neg pressure systems retro-fitted

Claremorrisdub · 27-06-2019 8:54am

yea in a high radon area, so have to do some checks i suppose, but trying not to let it monopolise the whole thing

Metric Tensor · 27-06-2019 7:08pm

Calahonda52 wrote: »

I have seen the neg pressure systems retro-fitted

FYI sometimes positive input systems are deemed more suitable because an extract system by creating a negative pressure inside the dwelling "could" inadvertently suck radon in to the envelope - albeit on a passing-through basis!

Case by case obviously.

Calahonda52 · 27-06-2019 9:02pm

Metric Tensor wrote: »

FYI sometimes positive input systems are deemed more suitable because an extract system by creating a negative pressure inside the dwelling "could" inadvertently suck radon in to the envelope - albeit on a passing-through basis!

Case by case obviously.

The ones I have seen have bored under the building.
The attached is in Athlone, building is c 30 years old, this work was done 10 years ago.
[have other pics from Tralee, where it goes up to the eaves from the ground, they also have a supply and extract in the canteen]

Claremorrisdub · 28-06-2019 8:04am

i have done a bit more research on it, and from what i can see, even if the radon sump isnt actually at the house(which we think it is, just cant confirm) it looks like the work to put one in would cost anywhere between 1k to 2 k, so to be honest, i can take that hit if need be. i suppose if the house was built pre 1997 its something i would have to deal with anyway. going to move in, get the testing kit and leave in place for three months, and see what it comes back with. looks like i have a few options (seal gaps first, improve ventilation second, passive sump third and then active sump, which seems to be the one that will have a high rate of success up to 1000 becquerels or more.

Wildly Boaring · 28-06-2019 1:23pm

The radon sump and pipe to cap don't actually do anything.

They are there to future proof and allow venting of radon if required.

Installing one would be easy enough on a decent build but done as part of an overall process to vent radon.

You are correct that the presence of one would mean a barrier is probably installed.

Your engineer is a bit daft looking for a black cover with sump written on it as the only type of cover possible. Every sort of cover is thrown over the pipe.

Claremorrisdub · 28-06-2019 1:34pm

Wildly Boaring wrote: »

The radon sump and pipe to cap don't actually do anything.

They are there to future proof and allow venting of radon if required.

Installing one would be easy enough on a decent build but done as part of an overall process to vent radon.

You are correct that the presence of one would mean a barrier is probably installed.

Your engineer is a bit daft looking for a black cover with sump written on it as the only type of cover possible. Every sort of cover is thrown over the pipe.

tell me about it, engineer really annoying me tbh. so just to double confirm so i can put this to bed, regardless of the condition of the barrier underneath, am i correct in saying that fitting a sump and either passive or fan assisted will do the job for me?

EDIT: image attached

Wildly Boaring · 28-06-2019 1:52pm

Claremorrisdub wrote: »

tell me about it, engineer really annoying me tbh. so just to double confirm so i can put this to bed, regardless of the condition of the barrier underneath, am i correct in saying that fitting a sump and either passive or fan assisted will do the job for me?

No not really, but might be enough.

You see radon can technically come up through all parts of the building. The barrier stops this.

Usually the barrier is enough on it's own and radon should then find a path of easier resistance to the surface. ie Out around the barrier and away. Modern barrier also has a layer of permeable stone under the building to aid this.

If you just retro fit a sump it would help ease build up under the building and allied with increased ventilation through the building should ease radon problems.

If you have actually have radon issues.....

Radon Barrier Query

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