A relatively simple 1st floor addition at Holborow St in Croydon Park posed some interesting detailing questions.

Firstly, the owner/builder wanted his new balcony to be at the same level as the internal floor of the house.

Secondly, he did not want any floor waste going through the balcony deck but he still wanted a level deck. Thirdly, he wanted to use stud walls but was concerned about waterproofing the base of the studwalls.

The first problem was easily solved. The builder set the balcony 150mm below the level of the internal floor, waterproofed the decking using the Wolfin System, then created a timber decking system over the Wolfin Membrane (putting down strips of Projex Shockmat matting under the timber battens to protect the membrane).

The finished timber decking was level with the internal floor level.

The second problem was also solved easily. He did not install a floor waste but did allow the balcony floor to slope at 1/100 so water could flow into the adjacent box-gutter.

However, he ensured that the timber decking itself was level. The timber battens holding the timber decking had gaps in them to allow water to pass through so there would be no damming effect.

Waterproofing the base of stud walls is always difficult because of the relative movement at the horizontal and vertical join. The Builder used the Wolfin System again - terminating the membrane 150mm up the studs and hanging it between the studs. The outside of the stud wall was finished in Blueboard.

The Wolfin was chosen because of its ability to withstand the movement of the lightweight materials used and also for its proven reliability in this type of construction.

The Wolfin installation was carried out by Steve Mason of Abasco Waterproofing, an experienced licensed Wolfin Applicator.

Wolfin themselves was able to issue a combined labour and materials warranty on the waterproofing – as opposed to the usual separate labour and materials warranties.