Aluminium decking

After the Grenfell Tower fire, the rules on combustible materials on the outside of residential buildings were tightened. For balconies on relevant buildings (residential blocks 18 m or more in height), decking has to meet a high fire classification, which rules out composite and timber. Approved Document B also expects designers to think about fire spread on balconies of other buildings.

For a house garden none of that applies, but the logic still helps. If a deck sits right against the house below a window, or against a timber-clad garden room, a non-combustible board is a sensible choice, and aluminium is the obvious one.

City flats in Holbeck, the Dock, Clarence Dock and around the centre often have balconies or roof terraces, and Victorian houses in Headingley and Hyde Park sometimes have flat roofs over back extensions. A deck there is a bigger job than a garden deck:

• Flats have no permitted development rights, so a new roof terrace or balcony needs planning permission from Leeds City Council. In a block, you will also need the freeholder's consent.
• A deck over a flat roof sits on adjustable pedestals so the waterproofing is not pierced, and the roof must be able to take the load.
• Guarding at least 1,100 mm high is expected on balconies and roof terraces, following Approved Document K.

You do not have to choose aluminium boards to benefit from aluminium. Many Leeds decks now use an aluminium subframe under composite boards: it costs typically £20 to £45 per m² more than treated timber, never rots, and is low-profile, which makes it ideal for laying over an old patio in a terrace yard.