Hello,
I have a stone/concrete rectangle (about 2x4 meters) below the kitchen window (garden tiles were once laid in wet cement) that serves as a patio but also as the roof for a basement extension - from the 1940s. There's an old hatch in the middle of the rectangle where pellets were previously dropped down to the furnace. A few years ago, I tried to seal around the old hatch with a membrane, but now I see it isn't watertight and water comes in during heavy rain. I'm thinking of laying decking here, partly because the traces of the hatch are unsightly and partly because there are cracked tiles in other places, but before that, I need to waterproof it. I'm considering either applying a few layers of cold asphalt over the entire slab or roofing felt and maybe roofing compound, and then the decking on top. What do you think would work well? /Pia
I have a stone/concrete rectangle (about 2x4 meters) below the kitchen window (garden tiles were once laid in wet cement) that serves as a patio but also as the roof for a basement extension - from the 1940s. There's an old hatch in the middle of the rectangle where pellets were previously dropped down to the furnace. A few years ago, I tried to seal around the old hatch with a membrane, but now I see it isn't watertight and water comes in during heavy rain. I'm thinking of laying decking here, partly because the traces of the hatch are unsightly and partly because there are cracked tiles in other places, but before that, I need to waterproof it. I'm considering either applying a few layers of cold asphalt over the entire slab or roofing felt and maybe roofing compound, and then the decking on top. What do you think would work well? /Pia
To ensure something remains leak-proof, it is probably best to ensure that the water beneath the decking drains away. Regardless of what you have underneath, there is a risk of leakage over time if the water can become stagnant.