barbour33 Posted September 2 Share Posted September 2 Hi all, I really hope someone can help me. I moved into my house 5 years ago, it has raised decking installed and would be somewhere between 10-15 years old. The decking is 1.5m above ground level in my rear garden, the area of the decking is 7m x 3.6m. I intend on trial holing down the rear of my property to see how far down my footing is. If my footing is over 1m deep then I would really like to remove the decking, dig down, pour the footings/slab, build a block structure that is tanked and water tight with external steps leading to a door. Something along the lines of 100mm or 150mm RSJ's with 300mm centres spanning 3.4-3.6m, fix and prop ply sheets up with acros in-between the RSJ's known as decking in terms of shutter joinery and then pour a 75-100mm suspended slab with steel on top. The slab would overlap 300mm over the block structure and sit on 300mm centred RSJ's which would then be paved/cladded and steps down into my garden or I could re-deck/clad the structure exactly as it looks now but new as far as externally goes. The height, width and length would not change other than the appearance of brick and patio instead of old wrotten timber decking or potentially look the same but new. Would I need to seek permitted development or planning permission for this? No one would ever be living in there. It will be for storage of Christmas crap, other crap and a gym room. As far as my neighbours are concerned nothing would change for them? Would there be consequences if I were to go through with this without informing planning permission/permitted development or the council? Im asking this because I know someone who has built a structure in there garden that they just built without asking anyone anything. Its 6m x 3m and when the neighbours complained all the council said was there are no rules on outbuildings under 2.5m in height and not consuming more than 50% of the garden. Do I fall into this category? Could I fall into this category if I build it say 300mm off the property so it's not attached to my property? If I were to ask the council or planner would I get away with providing a decent sketch or would it require an architect, structural engineer and building regulations? Link to comment Share on other sites More sharing options...
nod Posted September 3 Share Posted September 3 You will probably need building regs if it’s attached to the property I’d contact building control Link to comment Share on other sites More sharing options...
Russell griffiths Posted September 3 Share Posted September 3 Better off using block n beam with a structural concrete topping, no steel to rust away, nothing to temporarily support while you concrete it. Link to comment Share on other sites More sharing options...
ProDave Posted September 3 Share Posted September 3 If it is attached to the house it is not an "outbuilding" Due to the height it would have needed planning permission for what is there. It is almost certainly old enough it will not now be enforceable to make you remove it. So if repairing what is there, do NOT take it all down and rebuild. Repair in stages. There was a case here of someone taking down a similar structure and a neighbour photographed the old structure gone and the council then deemed the replacement was new and enforced it's removal. If I read this right you are hoping the house is built on very deep foundations and you hope you can excavate a lot of soil to create a "room" under your deck? I would not be doing that without advice from a structural engineer and it should involve building control. Link to comment Share on other sites More sharing options...
JohnMo Posted September 3 Share Posted September 3 I would say Raised of ground - need planning New structural design that is raised as well needs structural engineer Needs fall prevention ballastrade etc, needs a structural engineer. Nice project enjoy. Link to comment Share on other sites More sharing options...
barbour33 Posted September 3 Author Share Posted September 3 @ProDave Well I can pull it the structure away from the my house essentially making it an outbuilding and simply bridge my decking from the back door to walk on top of it. My neighbours can't see into my back garden, someone would have to trespass onto my property to take a picture of it. I'm not worried about digging below the footings. My property is a bungalow and where I would be digging has a flat roof. I'm speculating but the weight of the property will be alot less than that of a 2 story with a gable end. If the footing is shallow then I will just under pin in 1m sections if it's feasible and cost effective. Most of this work I will do myself I've been a shutter joiner/civil engineer for 17 years. Plenty of room to fit an 8t excavator and 6-9 tonne dumper for the digging process. At a 1600mm dig it cubes up to 90 tonne, it may seem alot but I could have this dug out and transported around the front to be collected via grab wagon by 11am if I started at 7.30am. @Russell griffiths The reason I didn't opt for block and beam was the fact that beams are heavy and expensive. 4"-6" RSJ's are manageable and I can get them at a good price. I would need to hire an excavator to lift the beams on. @JohnMo I'm confused why the height of the decking needs planning if it has already existed for a minimum of 10-15 years? How could they enforce me to remove it? Fall prevention will be bollards and glass panels at 1200mm high. This is exactly what is there now but timber. If it's an outbuilding does it really require structural engineer? Thank you so much for your replies,, it's greatly appreciated. I was lucky enough to bump into building control today during a drains test on site. I had a quick word with him and he said that realistically it's at my own risk. If no one sees it built no one knows it's there other than me, just looks like I've refreshed the old decking. The headache I would receive from the council and structural engineers over killing things would make it a nightmare. I might just build an outbuilding instead at the bottom of the garden... Link to comment Share on other sites More sharing options...
ProDave Posted September 3 Share Posted September 3 Lots of issues in the above post. As an existing structure built without PP it is too old for any enforcement action. Make a new structure which this would be without planning, and you start the clock ticking again. Up to you if you want to take the chance nobody notices and the council come looking. It needs PP because of the height of a raised deck, with or without under croft. Again if you want to dig a big hole next to your house undermining the foundations without SE input and without building control then you take the risk if it goes wrong or a different set of people from the council come to take a look. Why not replace the rotten timber and keep the existing deck and separately build a nice shed away from the house under permitted development rules for your storage needs? Link to comment Share on other sites More sharing options...
mjc55 Posted September 3 Share Posted September 3 53 minutes ago, barbour33 said: @ProDave Well I can pull it the structure away from the my house essentially making it an outbuilding and simply bridge my decking from the back door to walk on top of it. My neighbours can't see into my back garden, someone would have to trespass onto my property to take a picture of it. I'm not worried about digging below the footings. My property is a bungalow and where I would be digging has a flat roof. I'm speculating but the weight of the property will be alot less than that of a 2 story with a gable end. If the footing is shallow then I will just under pin in 1m sections if it's feasible and cost effective. Most of this work I will do myself I've been a shutter joiner/civil engineer for 17 years. Plenty of room to fit an 8t excavator and 6-9 tonne dumper for the digging process. At a 1600mm dig it cubes up to 90 tonne, it may seem alot but I could have this dug out and transported around the front to be collected via grab wagon by 11am if I started at 7.30am. @Russell griffiths The reason I didn't opt for block and beam was the fact that beams are heavy and expensive. 4"-6" RSJ's are manageable and I can get them at a good price. I would need to hire an excavator to lift the beams on. @JohnMo I'm confused why the height of the decking needs planning if it has already existed for a minimum of 10-15 years? How could they enforce me to remove it? Fall prevention will be bollards and glass panels at 1200mm high. This is exactly what is there now but timber. If it's an outbuilding does it really require structural engineer? Thank you so much for your replies,, it's greatly appreciated. I was lucky enough to bump into building control today during a drains test on site. I had a quick word with him and he said that realistically it's at my own risk. If no one sees it built no one knows it's there other than me, just looks like I've refreshed the old decking. The headache I would receive from the council and structural engineers over killing things would make it a nightmare. I might just build an outbuilding instead at the bottom of the garden... If you are hoping for neighbours not to see what is happening I suspect that you are wrong! It would be obvious that some major work is going on. Have you taken any professional advice on what you are planning, that is a lot of structural work that you are asking about, it would be folly without at least structural input. Link to comment Share on other sites More sharing options...
torre Posted September 3 Share Posted September 3 Sounds an interesting project, but do you ever intend to sell? Regardless of your engineering experience a secretly built DIY basement with no planning, building control or SE design would be a big red flag for any buyer or surveyor. Link to comment Share on other sites More sharing options...
JohnMo Posted September 3 Share Posted September 3 4 hours ago, barbour33 said: I'm confused why the height of the decking needs planning Your starter for 10 https://www.planningportal.co.uk/permission/common-projects/decking/planning-permission Then have a read of Approved Document K: 4 hours ago, barbour33 said: Fall prevention will be bollards and glass panels at 1200mm high Designed for what loadings and why? Link to comment Share on other sites More sharing options...
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