Sunken Garden office build

[JohnD]

Its more the opposite actually.

I think you can even build a sub-terrainian building without seeking PP.

You can build a 30m fallout shelter.

 

[bolst3r]

So im think the same... need internal floor about 300mm below external ground level.

understand the converns about damp etc, however due to soil (i mean clay!) conditions i am doing a RC raft with twin skin breeze/face brick construction.

With the right application of my DPM would i be right in thinking the damp ingress can be avoided?

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.

 

[CraigC86]

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.

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.

 

[John D v2.0]

Worth considering a planning application, depending on the likely effect on the surroundings, might be cheaper overall?

 

[CraigC86]

Worth considering a planning application, depending on the likely effect on the surroundings, might be cheaper overall?

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 !?

 

[CraigC86]

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.

Just to clarify - this is what im currently thinking