I'd like to add a decking to my garden, dimensions are 5m width x 3m depth. Am planning to have 3m joists laid vertically (about 50cm apart) and 5m decking boards horizontally As the soil is not very stable I was wondering whether about 10 C16 joists (2 inches x 5 inches), with bearers on both ends (3m apart), would work, could anyone confirm?
Thanks