GreenTips

Sealants often have a relatively short life span in terms of the life of the building. Building systems that rely heavily on the use of sealants to provide weather protection should be viewed with caution as such systems are only as durable as the sealant.

When selecting a sealant, make sure you select a product of the appropriate durability and flexibility for its task. Sealants need to be properly maintained and replaced at the end of their lifespan. Maintenance schedules for new buildings should always include details of the replacement and care of sealant systems.

Sealants are generally man made and can be solvent or water based or low VOC. In general select sealants that are low in VOCs and are water based.

Correct use of external trims and flashings can add significantly to the durability of the building. Many of the recent cases of leaky buildings in New Zealand have been the result of omitting or incorrectly installing flashings.

Wind seals and weather seals can also reduce building heat losses substantially. Careful selection and design of seals around door and window frames will reduce warm air escaping from the building or cold air being blown into the building. The window association of New Zealand has developed an installation guide.

Adhesives and glues are a common source of internal air pollution. If not installed with the correct safety procedures with good ventilation they can also represent a health risk to construction personnel, both those involved in applying the glues and those in the near vicinity. This is particularly true of glues used over large areas such as those used for flooring.

Water based low VOC glues should always be used in preference to solvent based alternatives.

The greatest volume of the pollutants emitted by adhesives will generally occur during application or directly afterwards. For this reason it s recommended that a bake out period is allowed for between application of the glue and occupancy.

The use of glues and strong adhesive tapes can result in difficulties separating materials for salvage or recycling on demolition. For this reason mechanical fixings are generally the environmentally preferable option.

Some innovative tape systems such as velcro tape are now being used to support wall panels in commercial situations to allow panels to be removed and replaced with ease.

An excellent background information on the use of adhesives is available here.

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