Miljøprojekt, 1134 – Evaluation of the Danish Statutory Order on Lead – 4 Exemption for repairs, rebuilding of and extensions to houses

Evaluation of the Danish Statutory Order on Lead

4 Exemption for repairs, rebuilding of and extensions to houses

4.1 Flashings and weatherings on buildings
4.2 Lead soldering of new zinc roof gutters etc.

4.1 Flashings and weatherings on buildings

Flashing and weathering products are used for sealing joints between roof and chimney, between roof and skylights, or similar points.

Since 2002, there has been a ban on such uses of lead for new buildings. The ban does not cover repair of existing buildings, and rebuilding and extensions (cf. section 2). On the basis of information from technical schools etc. [Larsen, C. 2005; Skipper 2005; Wolf 2005; Hansen and Hansen 2005; Rosholm 2005], it is assessed that this distinction between new buildings and repair work has not necessarily been widely known. This situation is changing, because building constructors and plumbers are now being trained to use the State Building and Urban Research guidelines "Blyfri taginddækninger" (lead-free roofing) [By og Byg 2002]. Since the Lead Order was introduced, training at technical schools has been based on repair work without lead and use of lead-free roofing such as extruded aluminium cast in polymer rubber. The students are therefore assumed to know the difference between repair work and building of new houses.

Generally, consulting engineers are considered to know and meet the rules, but the situation may be different for building workers. The building trade is rather conservative, and in Denmark, there is a long tradition for using lead roofing products, and long-term experience with alternative products is still not sufficient.

The study of the use of lead for flashings and weatherings was also based on contact to a number of craftsmen and building companies. The answers they gave vary.

Some small carpenters and plumbers state they no longer use lead flashings for new buildings. The companies contacted know the rules and are happy with the alternatives. For some uses, alternatives are sometimes considered to be better than leaded products – for instance lead felt may crack during work if the temperature is too low and sufficient care is not taken when putting the felt into place. Leaded products may also cause problems in relation to the working environment.

However, other companies (for instance one-man businesses) only use lead, because they are familiar with leaded products, and do not trust the alternatives. In addition, some local construction products wholesalers only sell leaded products and not the alternatives. Other statements made are:

Customers want to buy leaded flashings and weatherings.
Some suppliers of new houses stress that they do not question their clients’ choice of products [Korsbæk, 2005].

Generally, the alternative flashing products for new buildings are considered to be good, and in practice, all repair work can be made without lead. Useful alternatives are in fact available for all types of flashings and weatherings, and there are not practical examples of building projects that could only be completed using lead.

The standard recommendation for flashings etc. is polymer rubber aluminium (may, where required, be glued to the roofing material). This product is recommended for instance for eternite roofs [Brøndum 2005]. The product is covered by a 10-year guarantee, and is expected to last for an average of 20-25 years [Quist & Meier 2006]. For minor repair work aluminium repair tape of rubber bitumen (self-adhesive) may be used, and is supplied in a gloss and a lead-coloured version. Skylights are supplied with aluminium edge around bitumen. Also various types of sealing products are marketed.

The only real argument for continued use of lead is, thus, considerations of architecture. This argument may also be questioned, since repair and flashing products are marketed in colours looking like lead.

So far, the standard alternative polymer rubber aluminium alternatives are primarily marketed through suppliers of products for the plumbing and sanitation sector. Typically, the product cannot be bought at DIY centres, one of the reasons is that the price is approx. 50 per cent higher than lead. DIY centres therefore expect the customer base to be modest [Quist & Meier 2006]. On the other hand, DIY centres supply ordinary lead felt for roofing applications. This may be important for the customers (for instance carpenters and do-it-yourself customers), who buy most of their products at DIY centres.

Evaluation
Even if documentation proper has not been provided for uses of lead for flashings and weatherings beyond what is strictly necessary, substantial quantities are likely to be used. In view of the satisfactory alternatives for repair, rebuilding and extension work, only architectural considerations warrant the use of lead.

It seems technically justified to consider whether the general exemption for repair, rebuilding and extensions to houses can be limited, for instance by including only buildings that are listed or otherwise classified as worthy of preservation.

4.2 Lead soldering of new zinc roof gutters etc.

Lead soldering of zinc roof gutters and down-pipes is still allowed, both for new gutters and existing gutters.

Technical schools offer courses in lead-free soldering. However, for the purpose of repair of historical buildings, like churches and manor houses, lead soldering courses are also offered.

In practice, teaching at technical schools is based on the soldering agents available from the suppliers, and which, at the moment, contain lead.

One supplier offers a PU (polyurethane) adhesive which can be used for joining zinc gutters. PU technology has been developed mainly in Germany, and according to information, today the technology is widely used in Germany. In Denmark, PU adhesives used to be primarily known for the earlier negative experience (limited durability, tightness). Knowledge of positive experience gained later is not common in Denmark, and, therefore, available information indicates that technical schools in Denmark do not offer courses in the use of the products [Hansen & Hansen 2005].

[Carlsen 2005] confirms that some actors on the market do not believe that glue can replace lead soldering of zinc gutters, and therefore they only use lead for soldering projects. However, technical schools are preparing courses in lead-free processes for all types of plumbing and sanitation work [Hansen and Hansen 2005].

Evaluation
Statements obtained during this study indicate that lead could be avoided, also for soldering zinc gutters, if experience gained in Germany with the use of adhesives could be gathered and disseminated to technical schools and the plumbing and sanitation sector in Denmark.

It is recommended that the exemption granted be extended for a couple of years, and that work to collect and assess German experience with the use of adhesives for sealing zinc gutters be initiated. It might also be relevant to test and collect experience with adhesives other than the PU type. If results of such studies are positive, they should be disseminated to the technical schools and the sanitation sector in Denmark.