In 1998 when Necoflex was issued the first ever Agrement Certifcate for a radon resisting membrane there was quite a debate over an innovative detail which showed Monarflex RMB400 being used as a radon barrier AND a damp-proof course.
The Necoflex technical hotline was inundated with queries from concerned architects and builders asking if there had in fact been a mistake. After all, until then, damp proof membranes (typically 250 – 300 microns) were never detailed through masonry walls and required to serve as DPCs.
And rightly so, since I.S. 57 which covers polythene type DPCs specifically requires that membranes have a minimum thickness of 460 microns.
So why then was Monarflex RMB400 (400 microns) detailed in this manner?
Monarflex RMB400 is a multi-layered, extra strength, reinforced polyethylene which was carefully assessed and deemed fit for purpose as a DPC (as well as a high performance radon barrier).
And, given that one of the key entry points for radon into buildings is through designed cavities, it was absolutely essential to seal cavity walls effectively.
A continuous single membrane that excluded radon and prevented damp ingress was always going to be a better option than using a separate DPC where you have the risk of creating a slip-plane.
Monarflex RMB400 worked well and within a relatively short period of time, the detail showing a single membrane through the masonry wall became standard practice.
So what’s the problem?
The problem is that (as often happens with time) many people lost sight of the original concerns with regard to radon barrier performance as a DPC. With the introduction of lighter and thinner unreinforced radon membranes (typically 300 micron) many have not amended their details to show an appropriate Radon DPC through the walls. The result is that radon barriers which don’t meet the Irish Standard for DPCs are being incorrectly detailed and used.
To address this problem and take the guess-work out of radon edge-detailing, Necoflex has developed a brand new membrane called Easi-Load Radon DPC.
It is 500 microns thick and made using multi-layer polymer technology to give robust protection where a radon, air and moisture seal must pass through masonry walls. It is particularly suitable for cavity wall construction (900mm wide roll format) and can be used at all floor / wall junctions. It is intended for low to medium rise buildings and will not extrude under load. It also provides excellent mortar adhesion.
For further information please contact Necoflex on 01 802 3333