Flush to Ground Deck (Männedorf)
Background
The owners of this ground level condominium wanted an outside deck that was roomy enough for a dining table, Adirondack chairs and lounge chairs. For them it was very important that the deck surface be at the same level as their living room. Also, they did not want to have a step up or down from the surrounding lawn.
The grade of the lawn was nearly the same as the grade of the inside floors. This made it possible for me to build the deck flush to the door sills and flush to the grade of the lawn as well. From indoors, the deck and the lawn are, optically, an extension of the living room.
Materials and Construction
The deck boards, 21 x 95 mm (0.83x 3.74 in.) Brazilian walnut (also called Ipè and lapacho), were laid on 40 x 62 mm (1.65 x 2.56 in.) angelim amargoso sleepers spaced at 50 cm (20 inches). The sleepers are supported by 40 x 40 x 4 cm (16 x 16 x 1.6 in.) concrete pavers.
I fastened the sleepers to the pavers using galvanized angle clips. The chief motivation for this was to prevent the sleepers from shifting while I installed the deck boards.
All screw fasteners were of martensitic stainless steel. This material is compatible with tropical hardwood, magnetic and is tougher than austenitic stainless steel. The deck screws are 5 mm diameter by 50 mm long (#10 x 2 in.).
I separated the sleepers from the concrete with 10 mm (3/8 in.) rubber pads. The materials suppliers sell these pads as serving two purposes: 1) Prevent the sleepers from lying on wet concrete, and 2) provide cushioning in case of loose fit. I bought pads of various thickness and was able to shim under the sleepers if a concrete paver happened to be too low.
The owner was responsible for the excavation, subgrade and base. I placed a geotextile filter cloth on the base and covered this with 1 to 5 cm (0.4 – 2 in.) )of 4/6 mm crushed rock. The crushed rock provides drainage and is a convenient leveling material on which to lay the pavers.