Project description
Our garage is a detached single-storey block built in 2009, seven by four metres over the outer walls, and the flat roof measures about 28 square metres with a fall of roughly two degrees towards the outlet at the rear. I want to turn it into an extensive green roof planted with sedums and a few drought-tolerant grasses, because the kitchen window looks straight down onto it and at the moment all we see is cracked bitumen felt that bakes all summer.
Before anything is planted I need an honest opinion on the structure. The deck is timber joists at 400 mm centres with 22 mm boarding, and I still have the original drawings to hand over. Please calculate whether it carries the saturated weight of the finished build-up, which as I understand it can reach 120 kilograms per square metre once the substrate is soaked after heavy rain. If the answer is no, say so straight away and price the strengthening as a separate line rather than thinning the substrate until the numbers work.
The existing waterproofing is two layers of torched felt, roughly fifteen years old, and I suspect one small leak where the roof meets the house wall. I would rather it was flood-tested first and, at the slightest doubt, stripped and replaced with a new membrane carrying a root barrier, than covered over and forgotten under a tonne of growing medium. Above that I expect a profiled drainage and water retention layer, a filter fleece, and 80 to 100 mm of lightweight mineral substrate, with gravel margins at the parapet and clear access around the outlet.
Please quote for plugs or mats of at least six sedum varieties plus thrift and fescue, a temporary watering arrangement for the first season, tidying the parapet flashing and the rainwater outlet so nothing silts up, and materials and labour listed apart. I would like the work done in a dry spell and finished within two weeks of the start.
Before anything is planted I need an honest opinion on the structure. The deck is timber joists at 400 mm centres with 22 mm boarding, and I still have the original drawings to hand over. Please calculate whether it carries the saturated weight of the finished build-up, which as I understand it can reach 120 kilograms per square metre once the substrate is soaked after heavy rain. If the answer is no, say so straight away and price the strengthening as a separate line rather than thinning the substrate until the numbers work.
The existing waterproofing is two layers of torched felt, roughly fifteen years old, and I suspect one small leak where the roof meets the house wall. I would rather it was flood-tested first and, at the slightest doubt, stripped and replaced with a new membrane carrying a root barrier, than covered over and forgotten under a tonne of growing medium. Above that I expect a profiled drainage and water retention layer, a filter fleece, and 80 to 100 mm of lightweight mineral substrate, with gravel margins at the parapet and clear access around the outlet.
Please quote for plugs or mats of at least six sedum varieties plus thrift and fescue, a temporary watering arrangement for the first season, tidying the parapet flashing and the rainwater outlet so nothing silts up, and materials and labour listed apart. I would like the work done in a dry spell and finished within two weeks of the start.
Other / Miscellaneous Cash, Bank transfer
