Paul Garner, technical director of Uponor Housing Solutions, talks about the changes to the NHBC standard and how it affects the installation of plastic plumbing
IN September 2006 NHBC changed its standards and this will impact on the way plastic plumbing is used behind plasterboard walls. NHBC is the standard setting body, which provides warranty and insurance for 80% of new homes in the UK and sets the construction standards for the house-building industry.
The standard
NHBC Standard, Chapter 8.1, Internal Services, Clause S2 requires plastic piping within walls to be detectable; it states:
'Where plastic pipework is in or behind wall surfaces, and would otherwise not be located by a metal detector or similar equipment, a metallic tape should be applied to the pipework.'
Plastic plumbing has simplified pipework installation in new homes. It comes in a number of variations which will be affected by the changes;
· Polybutylene;
· PEX polyethylene cross linked - (which can be used for all plumbing applications and is the most widely used in the UK);
· Polypropylene + PVc.
The exception is multi-layer, PE-RT/Al/PE-RT (polyethylene raised temperature / aluminium / polyethylene raised temperature) which contains a metallic element allowing the pipe to be detected.
The solution
For all installers using plastic pipes which do not incorporate a metallic element, measures have to be put in place to make sure the pipe is detectable, to ensure the safety for the end user. Uponor Housing Solutions, for example, has been at the forefront of innovations in flexible plumbing for many years and has a ready made detectable solution, a multi-layer composite (MLC) pipe range which incorporates an aluminium layer within the construction of the pipe. This also helps maintain the current level of labour and materials' costs that plastic pipe installers experienced before the standard was introduced.
Solving the problem of pipework which is not detectable is not straightforward. Some ways have been suggested to allow pipes to be detected. One method involves wrapping pipe in metallic foil or attaching metallic tape with adhesive to the pipes. Here, it is important to make sure the adhesive complies with the pipe manufacturers' specification, to prevent any reaction between the pipe and the adhesive. NHBC is aware that testing of adhesive compatibility could take several months before completion - and advise adopting an alternative if in doubt. An additional solution is to stick a metallic strip to the backing wall as close as possible to the pipework. Here, the installer must maintain the pipe within the boundary of the tape.
However, there would be an increase in the time taken by the installer. The preferred alternative to these proposals would be to use a multi layer composite pipe with an internal metallic element such as the MLC range from Uponor.
Popularity of plastic
Quick connections and flexible application have made plastic popular with installers, especially for those on tight schedules. At present, ease-of-use and labour costs are the recurring themes when comparing plastic and metal pipe systems. Currently plastic can be used in the majority of hot and cold water services applications, as an alternative to the traditional metal. These were the factors examined by BSRIA which carried out an independent installed cost analysis, comparing a MLC pipe system to a traditional alternative.
The study aimed to compare the labour and material cost of installing heating pipework from a domestic boiler to four radiators using multi-layer composite pipe work or traditional 15mm soldered copper pipework. The results showed that installing an Uponor system saved 13% on installation costs and a massive 52%1 on labour. Examination of the figures shows the time is saved on the jointing procedure, as soldering is not required, hence significant time and health and safety issues were removed.
Conclusion
Plastic plumbing is now an established method for plumbing-in pipework throughout new homes and by setting the new standard the NHBC has provided further protection for the end user. The installation of plastic pipe has become more complicated unless the pipes already contain some type of metallic element, such as the aluminium layer contained in MLC pipe.
Figure accurate at the time of testing
Uponor Housing Solutions
T: 01455 550355