L-shaped shed - is it possible?

[PaulUszak]

It's a shed and you can make your own decisions, but the standard safety factor for live (removable) load is 1.6. So you actually have to cater for at least 3200 kg. That's one and a half Defender 90s. Plus you'll probably use engine hoists, trolleys or jacks? Those things create punching shear that would just pop straight through a suspended ply sheet. It would be dangerous. The freezer sounds heavy too, especially it's (4?) feet.

Wind aside, I think that you're looking at a substantial concrete floor. Probably >= 100 mm thick with mesh reinforcement and a DPC. Perhaps float finished /screeded if you want it smooth. Any chance it could be ready mixed off a truck? Otherwise that's ~1 m^3 of concrete to mix and it's nice to have it all poured in one go, but not absolutely necessary.

The ground slopes and is soft. That'll have to go (offsite?) and be replaced with compacted Type 1 fill, digging down till you hit firm ground. Dig a test hole outside of the shed's footprint and investigate the ground. This is one of the most important aspects of successful outside construction.

You're really talking about a garage floor.

Rotated roofline - but now with a much longer pitch hence more wood. Small 2000 long steel beam possibility?

Or, getting a little elaborate in trying to lower the roofline - . Not recommended if at all possible.

But now a tip. Redraw your sketch to scale. It's quite confusing to have walls 420 and 200 almost the same length

 

[ericmark]

I have sat in this "Shed" drinking coffee and watching the rabbit go by in the foxes mouth, it was on about 4 levels and was a really odd shape, and the woodland owner lived in it full time. The wood burning stove keep it really warm and the trees may have protected it from wind, but one did fall on the structure and squashed one of the bedrooms, which had a tarp on it for years after.

It seems the council wanted to charge the guy for every "shed" he had, so he moved them all and joined them together, so then he only had one charge, oddly the stone build cottage in the 20 acres of woodland had no council tax, how I don't know.

What you can and can't do it seems is down to who knows what you have done. There are so many rules and regulations no one can keep up, in the end he had to move out, as home help could not really look after him there.

The track was not too steep, but would not stand the weight of an ambulance, and a SSSI woodland so could not enlarge the track.

Where I live you can't get out when it snows, so always a good stock of food etc. So with this virus we are OK we always have keep a good stock, the only worry is power cut.

 

[Nesmy]

Hi PaulUszak,

Thank you for your contribution again. As I understand pouring concrete floor would be most suitable. There isn't enough access however for a truck to access my back garden so I would have to do it by hand. Tell me whether I understand the sequence correctly:
1) I dig deep enough to reach solid ground.
2) Fill in excavated part with type 1 and leave 10 cm for the conrete.
3) Lay PE membrane
4) Fill in with concrete and reinforce with a mesh

It may be a silly question, am I to attach walls to that concrete slab I just poured? Or should I lay a course of blocks/bricks around the perimeter and then attach walls to them to avoid moisture?

Also, If I make everything level and there is 15 cm difference in height, that means in the highest part of the ground there now will be a recess in which the slab is, does soil around it need to be supported? Or am I missing something? Any specific type of concrete to use?

 

[PaulUszak]

Yeh, hello. I've been high for a few days Sorry.

Some ideas here... But yes, your overall points 1-4 are correct.

Everything depends on your budget for this thing. You could build your wooden structure directly onto the slab, of course. For a bit more money, look at typical conservatories. They have a dwarf wall around the perimeter. It's usually a cavity wall for a conservatory (as it's a habitable space and thus within the purview of building control). A shed could simply have two courses of concrete blocks instead. They would provide 99% water exclusion from rain splash and protect the wood. A cavity would prevent moisture even further. Tip: look at the wooden posts on your OLD fence. They're okay aren't they? It's only where the wood touches the ground that rot occurs.


Then either install a wall plate along the slab, or atop the dwarf wall. On the slab you'd drill through and screw using frame fixings. Atop, you could go with inverted restraint straps (in a non bondage meaning) tying directly into the columns. Then clad between the columns with OSB.



Most important tip: You should take everything I say with a small pinch of salt. I'm/was an Engineer and the last thing I designed was a motorway bridge with a standard DOT service life of 120 years. That's not the same design objective as a shed. And not the same economics. A shed to me means a portal framed Amazon warehouse. I'm not a 'builder'. You can fake a shed and it doesn't really matter. That might be what @ericmark was referring to above, with some wisdom. There's a builders' forum here that might offer cheaper or more expeditious solutions for a small project. And some geezer built his slab like this. Just be mindful of the ground conditions. But happy to continue if you like...


Your current footprint actually looks like this:

Given the irregularity of the ground, there's a fair chance that the 1800 x 2000 section will crack off, especially with such a thin slab. You might want to consider a movement joint along the line extending wall 1400. No biggie and it helps to reduce the pour.