You can build a 30m fallout shelter.
Sunken Garden office build
- Thread starter Jn46
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You can build a 30m fallout shelter.
is this fuelled by a warm deck restricting the head clearance? I spoke to my architect (as i'm doing another house extension) and he said the benefit were negligible. I've decided to put my insulation internally between the rafters, making sure to leave a small air gap behind. This means i'll only need to sink mine <100mm so water ingress isn't really a concern. The area it will be situated on, is about 15m x 25m and is 2" of gravel on soil so it drains really well. I'm planning on installing a small French drain around the perimeter to a couple of soak-aways, it's probably overkill but It should work for me.
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its a combination of factors
1) i want 2.4m internal head height
2) the building is 5m x 6m so according to the span tables i will need 9 x 3 roof joist (can go for 5 x 2 but need to start messing about with RSJs etc)
2400mm head height height + 220mm joist + 25mm cross batten + 100mm firing + 25mm for 18mmOSB and roofing material
i wasnt going to insulate the floor as its just a gym, i will do the wall cavity and a cold roof. But if i wanted to insulate floor in future i could still put down some insulation + screed layer and have plenty of head height remaining.
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Worth considering a planning application, depending on the likely effect on the surroundings, might be cheaper overall?
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Greenbelt im afraid, i did try but was rejected. the local planning rules only allow for 25% increase in footprint of existing dwelling under full app and we are using this aloowance on a main house extension.
its a shame and bonkers really as i had proposed a hipped roof building which was of exact same style as our georgian house... so instead of a building inkeeping with the exisiting style we are instead doing a square featureless PD box.... but thats allowed !?
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Just to clarify - this is what im currently thinking
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Hi there, very late to the chat, but did you build the sunken garden room. If so, has it flooded since?
I was hoping to self build something similar. 9x7 square meter overall foot print with 75cm gap on 2 sides and rear. I wanted enough room to stand a sheet of timber upright 2440mm. Don’t need it to be habitable in terms of external thermal insulation in the roof etc as it’s only going to be for woodwork and painting as a hobby but I can’t see it being less than 3m tall and that’s going to be quite large. Was thinking. Insulating between rafters and excavating 500mm a larger area than the building and landscaping the rest of the garden accordingly with terracing. Using ground screws as a footing and putting in a soak away that was much bigger than the minimum requirement. Would it be insane to do so?
I was hoping to self build something similar. 9x7 square meter overall foot print with 75cm gap on 2 sides and rear. I wanted enough room to stand a sheet of timber upright 2440mm. Don’t need it to be habitable in terms of external thermal insulation in the roof etc as it’s only going to be for woodwork and painting as a hobby but I can’t see it being less than 3m tall and that’s going to be quite large. Was thinking. Insulating between rafters and excavating 500mm a larger area than the building and landscaping the rest of the garden accordingly with terracing. Using ground screws as a footing and putting in a soak away that was much bigger than the minimum requirement. Would it be insane to do so?
Just found this thread so a couple of points if still of interest to peeps.
On Craig's drawing 50mm could be lost straight off by pitching the roof from the middle so firring 0 to 50 to 0.
9x3 or a steel plus 5x2 is to me a no brainer!!
It is of course completely feasible to build a partly sunken building that is dry BUT it won't be cheap and it needs proper detailing. You would simply form a concrete tank to the required depth and bring the walls 150 above ground to sit your structure on. It would need external taanking and might need provision to resist flotation dependant on where ground water level is. The entrance would need thought.
On Craig's drawing 50mm could be lost straight off by pitching the roof from the middle so firring 0 to 50 to 0.
9x3 or a steel plus 5x2 is to me a no brainer!!
It is of course completely feasible to build a partly sunken building that is dry BUT it won't be cheap and it needs proper detailing. You would simply form a concrete tank to the required depth and bring the walls 150 above ground to sit your structure on. It would need external taanking and might need provision to resist flotation dependant on where ground water level is. The entrance would need thought.
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