In E-Bulletin 39

Tenmat advice on lightweight joists

Over the past 20 years the use of lightweight joists has grown dramatically, they are now used  in many timber supported constructions. They offer advantages over solid timber joists; low weight, longer spans and access for services. However, significant problems can occur when they are exposed to a fire situation and the fire penetrates the plasterboard layer, with the most serious incidents resulting in the premature collapse of ceilings.

There have been extensive tests carried out comparing the load supporting capability of lightweight joists compared to solid timber joists when directly exposed to fire. In a loaded situation, a typical solid timber joist can maintain loadbearing capacity for 15-20 minutes, whereas a lightweight joist has been seen to collapse after only 3-6 minutes!

The use of indoor ventilation has also increased significantly in recent years, and it has been shown that good ventilation can significantly reduce the spread of viruses. It can be expected that the amount of ceiling penetrations for increased ventilation will grow, making improved fire protection ever more important.

To ensure the best protection, use fire-rated products from reputable sellers, who can provide test data to prove that the products meet your requirements. Also, be aware that any ceiling penetration throughout a building can provide a route for fire to spread and cause damage, so protect anywhere that enters the ceiling with the appropriate product. You can learn more here; or contact the team at Tenmat