Cheaper, stronger, quicker - these are the claims made for overcladding, the process of fixing cellular PVC-UE roofline products over existing fascias, bargeboards and soffits. However the realities are somewhat different. The practice of overcladding - as opposed to removing timber elements and replacing with intrinsically strong, durable, purpose-designed PVC-UE systems - can threaten the very structure of the roof it is supposed to improve.

TAKING RISKS WITH ROT The main problem with overcladding is not with the cellular PVC-UE products themselves, but with the timber they are adhered to. Timber is vunerable to water penetration both from the outside - as a result of inadequate protection and poor maintenance - where broken tiles, cracked verges, torn and decayed roofing felt, and generally old and bad roofs allow water to penetrate. This water penetration causes the gable ladder, bargeboards, soffit and fascia to rot so, by applying PVC-UE over such material, you are not solving maintenance problems, buy merely concealing decay. This is all too likely to spread to the structural roof timbers in the form of dry rot, ultimately causing a far greater mainenance problem - and one that is expensive to rectify.

A PRICE SENSITIVE ISSUE As it becomes increasingly recognised that overcladding timber in a poor condition is a false economy, some people have taken to treating the wood before overcladding. However, applying the remedial treatments for rot, as outlined in BRE digests 299 and 345, is an essential but expensive undertaking, and therefore offers no cost advantage over simply removing the timber - and therefore the risk - and installing cellular PVC-UE in its place.

PURPOSE - DESIGNED STRENGTH Nevertheless, say overcladding's supporters, the fact that PVC-UE is being applied on top of timber roofline elements makes the whole construction stronger - a convincing argument for many householders. To say this is to confuse two issues: rigidity and strength. Roofline systems from a reputable supplier have been purpose-designed for the application, and have been tested for their ability to perform. They are strong enough for the job, when attached with a number of fixings as the manufacturer recommends, to the structural elements of the roof - rafter feet, gable ladders and noggins. Products made specifically for overcladding, on the other hand, need the rigidity of the timber they are attached to - a worrying fact, given that timber is prone to rotting - and require a great many more fixings than an independant system. In fact, overcladding offers no strength advantage over a purpose designed cladding product, and arguably far less durability given the unsound base to which the PVC-UE material is fixed.
THE FASTER OPTION The other advantage claimed for overcladding is that it is far quicker to install than total replacement, and because of the time constaints of many projects, or the time costs for contractors, the perceived speedier option does, at first, seem more attractive. Look more closely however, the speed issue is not so clear cut. To overclad an existing fascia, it is necessary to remove the original gutter and fittings. Of course, if this is done carefully, it is possible to re-use the components, but to dismantle without damaging it is a laborious and time consuming process - hardly the quick, easy job that most contractors would prefer. Even when the old system has been removed, it still takes time to obtain replacement fittings and seals to ensure the integrity of the installation, and to avoid the return visits which again add to the time cost of the project. Total replacement on the other hand, usually billed as the slower option, offers a speed advantage. Using modern tools, such as a sabre saw, the fascia, soffit and gutter can be removed simultaneously, which is obviously much quicker than careful dismantling. After the replacement work has been done, the only extra expense is the material price of the new gutter which, when compared to sourcing new fittings and seals, is a more cost-effective option. In the same way, overcladding a barge board can appear to offer savings in time - but at what cost? To overclad a bargeboard is to ignore the threat of an inadequate verge, which could be very dangerous to the integrity of the roof. Damage to the verge could easily be the cause of rot which, undercover of the cladding, will continue to decay, threatening its structure.

REPUTATIONS AT RISK When all these factors have been considered there is a final issue to be aware of - that of reputation. Many hosueholders, and even many people within the industry, are unaware of the potential problems over overcladding, and it can be persuaded that it represents a quick, cheap solution. Looking a few years ahead however, what once appeared the easy option, can turn into a nightmare of structural problems, rot, worry and expense - with much of the problem not becoming obvious until it has reached major proportions. When choosing between total replacement or overcladding, there are two questions to be asked. Firstly, is it worth taking risks with the roof, and secondly, by choosing the overcladding option are you putting the good name of your company on the line?