We now have the response to the consultation on fire safety post Grenfell, with news that all new blocks of flats extending six storeys or higher could require sprinkler systems under proposed government plans.

Richard Steer

The government is not proposing earth-shattering changes; indeed, some say the proposals do not go far enough. But they will have an impact on construction costs.

Under current guidelines, sprinkler systems are required for buildings of 30m (98ft) – around 10 floors – or higher, but ministers will now decide whether to decrease this to 18m, which is around six floors.

Several immediate issues spring to mind following these recommendations, the first being the construction challenges created by the installation of the new sprinklers.

These will include making provision for additional incoming mains water, plant space for the sprinkler tank and pump rooms, the installation of an emergency power supply to support sprinkler pumps, plus an additional 150mm service zone per floor and an additional riser space.

Grenfell Tower

Source: Shutterstock/Sasa Wick

In terms of cost implications, the price of a building’s frame will inevitably increase to accommodate the additional service zone, as will the facade cost because of the enlarged area. Internal walls will become higher and there will be new expenses created as a result of forming an additional riser through the building.

There is also the impact of a loss of space to consider, because of the potential reduction of the net internal area when locating the sprinkler tank and pump rooms.

So building costs will increase, but as every block has its own design specification – differing in size, shape and efficiency – it is difficult to quantify by how much.

Nevertheless, we estimate that the approximate increase in overall construction cost would be between £108/sq m and £140/sq m. This would be from a base cost of £2,420/sq m, using a new-build scheme on the outskirts of London as a guide.

We are therefore looking at an uplift in building costs of between 4% and 6%. Typically, developments may only hold a 5% contingency, so this could eradicate that sum in one go.

It is important to stress that changes in fire regulations are to be welcomed if they have the potential to save lives. However, it is also important to appreciate what they mean in terms of increased build costs.

Richard Steer is chairman of Gleeds Worldwide