PVC Products

Entropy is the scientific theory that explains the random molecular disorder of the universe. Living things apparently combat this by creating temporary order out of the chaos. But everything else is in an inevitable state of decay.

Inevitable decay is not something you will hear much about from building materials salesmen, who prefer the idea that their products will last forever. Adverts for PVC replacement windows and cladding, for example, often give the impression that the material is "maintenance free", and, for the scientifically uneducated, this must sound like a wonderful thing. Unfortunately, it is not true.

The idea that a building might survive without maintenance is a seductive one, especially for the millions of people who embarked upon home-ownership simply because they couldn't find anywhere decent to rent. But finding themselves with the huge financial responsibility of a mortgage, they would rather not then be told that they should be spending between two and five percent of the value of their homes every year on keeping them in basic good order. They might quite fancy the idea of splashing out on a "Changing Rooms" - style makeover of the bedroom or lounge, but spend a thousand quid on scaffolding, overhauling the roof, and painting the outside joinery? You must be joking. Nobody at the Building Society warned them about that . Hence the attraction of the "maintenance free" PVC option.

A recent reader's letter describes a typical scenario. The reader lives in a fairly modern purpose-built block of flats, and someone on the residents' committee has decided that, in order to "reduce maintenance costs", all the windows, fascias and soffit boards should be replaced with PVC, at an estimated cost of over £100,000. The current annual amount they are spending on exterior maintenance is, of course, zero, because the windows, fascias and soffits have not actually been painted since 1976.

Imagine if we adopted the same approach to our clothes. Or teeth. Don't bother to clean them or look after them. Just let them rot away and then buy some plastic ones. Society would judge anyone who behaved like this as foolish, or deranged, or both. They would be sent for psychiatric counseling and their children would be taken away from them. But when it comes to the buildings that we live in, it seems to have become socially acceptable to allow them to rot.

The PVC salesmen exploit this inertia by reassuring us that it is really alright to neglect our homes. It is not out fault that the windows have rotted, they say; it is because they were made from that pesky old-fashioned stuff called wood. Time to get modern and use space-age materials that will last forever.

Only they won't. I have previously explained in this column why sealed double-glazed window units are all doomed to eventually mist up between the two panes. And the law of entropy means that the PVC frames themselves will also decay. PVC inevitably becomes discoloured, and brittle, and, because of its high thermal expansion coefficient, it can even crack. This last problem is especially common in PVC replacement fascias and soffit boards, which need very careful fixing and - dare I say it - maintenance? - if they are to remain intact for more than a few years.

But however it is treated, PVC has a very definite life expectancy, whereas timber, being a living thing, can last for centuries. It just needs a bit of tender loving care to keep the entropy at bay.

Q. I live on an estate of houses with much white boarding - soffits, fascias etc. Firms come around offering maintenance-free white PVC. Some firms cover the surfaces of the existing wood soffits with thin plastic boards; others insist it is better to remove the original wood and replace entirely with PVC. Few of us still have the original woodwork which, of course, has the disadvantage of needing repainting at intervals. Which is the best option?

A. 'Maintenance-free' PVC-U is something of a myth. It won't last for ever. It becomes brittle through exposure to sunlight, and discoloured by airborne pollutants. PVC-U must also be fixed using slotted holes to allow for thermal movement. If this is not done then the boards can buckle and split. Fastening PVC-U boards over existing timber is a real bodge job, as it will trap moisture underneath, and the timber will rot. Why do you think there are so many of these firms around touting for work? It's because they are making a fortune for doing not very much. For the money they charge you could pay to have the woodwork maintained and painted for fifty years.

Q. We had an extension built and now have exposed white plastic windows and waste pipes, a brown pipe going into the drain, a grey plastic soil stack, and black plastic gutters and down pipes. Would the life of all this plastic be prolonged if painted, and is there a special paint for the job?

A. All plastics become brittle through exposure to u/v light, but not at the same rate. This will depend upon the type of plastic, the colour, and the amount of u/v stabiliser used in manufacture. Your white internal waste pipes are probably polypropylene, and the windows, brown and grey drainage pipes, and black guttering, are PVC-U.

The biggest maintenance requirement for PVC-U (the 'U' stands for 'unplasticised') products is to keep them clean. The plastic surfaces seem to attract dust and pollutants - possibly by electrostatic attraction - and white PVC-U can quickly become dirty. So all PVC-U windows and roofline products should be washed with detergent at least once a year - more frequently in towns or areas close to the sea. All plastics will last longer if painted. ICI/Dulux make Weathershield PVC-U paint - for use on weathered PVC-U windows - which will need rubbing down and re-coating every few years, like all paintwork, but ordinary spirit-based undercoat and gloss can also be used.

Many more readers' questions like these are answered in my book, "The Sunday Telegraph Guide to Looking After Your Property" - click on books towards the bottom of the menu for more information...

"Beware of all enterprises that require new clothes", said Henry David Thoreau, the American philosopher. Had he been a builder he might have said, "Beware of all enterprises that require new materials", because stepping into the unknown is always a risky business, as much with your home as with your career.

Of course, by "new" I mean new super duper, rather than new just out of the packaging. After all, there's nothing wrong with freshly-burnt bricks, recently-quarried stone or newly-seasoned timber; the characteristics of all these materials are known and understood, so we can use them in situations where they will perform well for years.

No, it's the "new generation" materials - specifically plastics - that we should be wary of. They haven't been around long enough for us to assess their limitations - and they are being promoted for uses that they are clearly not up to. Plastic guttering creaks and groans in the sunshine as it expands and contracts, and the inevitable result is that it comes apart at the joints and lets rainwater run down the walls. There is growing evidence, too, that plastic pipes leach chemicals into the drinking water which can make men infertile. There is a historical irony here - it is said that the Romans went mad through lead poisoning from their water pipes; and now, 2000 years later, we are wiping ourselves out with ours.

Plastics may appear stable, but they can get quite nasty when asked to mix with other plastics - PVC-sheathed electrical cables and expanded-polystyrene loft insulation, for example, combine to form a sticky goo which eventually leaves the wires exposed and liable to start a fire in the roof space. If you have this combination in your home than get it checked out.

But of more widespread concern is the fact that plastic water pipes are now used for repairs and alterations to home plumbing systems, which may lead, paradoxically, to risk of electrocution.

Let me explain: water conducts electricity; that's why you shouldn't have electrical sockets or light switches in the bathroom. So any metal object in contact with water, such as a stainless steel sink, a central heating radiator or even the steel taps on an acrylic bath, could become electrically live if a short-circuit occurs somewhere else in the building. So for safety these common household fixtures must be connected to earth with thick green-and-yellow-sheathed earthing cable - the process is called earth bonding. In the past, when all water and gas pipes were copper or lead, it was sufficient to earth bond the kitchen sink to the nearest pipe, because the whole plumbing system was connected to a proper earth at the electricity company fuse board.

The introduction of plastic pipes, however, has meant that the earth bonding may be interrupted, because plastics do not conduct electricity; so if by accident the sink should become live, there will be nothing to conduct the electricity away safely to earth. Even one push-fit plastic pipe connector will be enough to break the circuit.

Plastic pipes may have a part to play in the future of construction, but just now they are posing a few questions. If you think you may have plastic anywhere in your plumbing system then play safe and get your earth bonding checked by an NICEIC approved electrician.

Qualified electricians display the NICEIC logo - or call the National Inspection Council for Electrical Installation Contracting on 0207-582 7746 for a list of local members.