Timber Shed

[Bellefield]

Not sure if this is the right forum, so please move if I've got it wrong.

 

I'm looking to build a storage shed in an underground garage, just to store bikes, diving gear, tools and the like and would appreciate some advice on one or two of the aspects.

 

We've got a couple of back to back garage spaces in the underground carpark here (I live in an apartment block now), one of them backs onto the wall with the other in front of it, so you can only really access the one against the wall via the other one.  We've currently got a plastic garage against that wall, its only small 5' x 6' and the missus is looking for something bigger since we bought eBikes (yes its cheating, but it gets us out on the hills more).

 

She was looking to buy a new shed, but we are limited by the headroom in the garage (220cm) which most larger sheds can't fit, and the width is also limited to about 220cm, but we can go back 350cm.  Most of the sheds she picked out were just too high for the space, or too flimsy, and then she found a metal asguard motorbike garage that was ridiculously expensive for what we need, and luckily they said they couldn't deliver to the island, so I said I'd build one, and I'm looking forward to digging out the tools again.

Anyway, my main question is, as its a concrete floor on this garage, and its not really prone to flooding (although we have had one flood in the last 15 years here) am I ok using the garage floor as shed floor, or should I lay down a wooden floor over the concrete?  

 

We haven't got much height to work with so I'd prefer avoid adding a layer to the garage floor, and effectively just use it as the shed floor and just build up the walls around it.  I've never done it this way before, always put floor joists in and a wooden floor.  It feels like cheating to use the concrete floor that's there but I can't figure out why I shouldn't.

 

If I use the concrete floor as the shed floor, is there anything I need to consider regarding damp, oil, etc, that might effect the wood? or anything I need to do, like putting a DPM under the wood, or is that overkill?  It'll just be used for storage, so I won't be working in there (there are no electrical points down in the garage anyway!)

 

I'm just going to use a flat roof as there will be no rain or weather implications and it gives better use of the available headspace, and I'll put in windows on three sides to help with lighting (see point about about no electrical points down there).

 

I reckon we are here for a while, so want the shed to last as long as possible.

 

Thanks in advance for any advice you can give me.

Edited August 13, 2020 by Bellefield

[Conor]

Certainly a unique situation!

 

We had mild steel storage units in the floor of an apartment building I lived in years ago. Directly on the ground. Everything was always wet. Once moisture got in, it never left.

 

If you are confident you won't have surface water flowing in (only takes a small amount), when what you propose is fine.

 

If laying a timber shed or structure, I'd first install a ground plate with pressure treated timber. Unlikely to rot in the time you describe.

 

To save time, you could get a shed that matches your dimension, and just modify the roof so it's flat, rather than pitched?

 

 

[Bellefield]

7 minutes ago, Conor said:

Certainly a unique situation!

 

We had mild steel storage units in the floor of an apartment building I lived in years ago. Directly on the ground. Everything was always wet. Once moisture got in, it never left.

 

If you are confident you won't have surface water flowing in (only takes a small amount), when what you propose is fine.

 

If laying a timber shed or structure, I'd first install a ground plate with pressure treated timber. Unlikely to rot in the time you describe.

 

To save time, you could get a shed that matches your dimension, and just modify the roof so it's flat, rather than pitched?

 

 

nice idea about modifying an off the shelf shed, I guess though I'm not particularly impressed with the quality of the shed's I've seen so far, and I'd rather spend the money and time on quality materials.

 

Good point about the pressure treated timber, I'll use that for the base frame.

[andyscotland]

Couple of thoughts:

• Damp might be an issue, as you say there's been one flood before, but also from the concrete, and/or it only takes someone to spill something / have an oil leak or whatever on their car to become at least an annoyance and/or do some damage to the contents / structure.
• The walls might be a bit wobbly with nothing to tie them together / hold them straight at the bottom. Might make it a bit less sturdy around the doors in particular.

You could probably solve those quite cheaply / easily and get a better result without losing too much height by:

• Cover the area with a DPM with enough overlap to bring up the sides a bit
• Then a layer of thin OSB - 9mm should be fine. For a 2200 x 3500 base you'd have 3 boards running side to side.
• Screw the timber wall plate to the OSB perimeter from the bottom before you lay it. Your side-to-side walls can be in one piece along the long side of the sheet, it'd be easier to do the front-to-back as three pieces one on each OSB sheet probably so you can lay them one at a time rather than trying to build the whole floor upside down and flip it after. Once the sheets are in position you can put a second continuous piece of timber over the top to join it together.
• That should be pretty solid already, but to make it really robust you could screw a few bits of plumber's band / thin metal repair plate across the butt joints in the middle of the floor in a few places.
• Build your walls and turn/staple the DPM up the outside of them a suitable distance above the floor.

That should give you a reliably dry, sturdier structure with not a lot of extra cost/effort and only 9mm extra height. Obviously for the best flood etc protection you'd want to continue the wall plate / turned-up DPM across the doorway, but that will give you a step over on the way in. If you'd prefer to have it flat / level I'm sure you'd be fine just stapling the DPM over the edge of the OSB there.

[Ferdinand]

First things first.

 

2 hours ago, Bellefield said:

we bought eBikes (yes its cheating, but it gets us out on the hills more).

No it isn't; it's an efficient and appropriate answer to your requirements. 

 

?

 

Second things second.

 

On damp, I think what you want will be OK with whatever method, provided the stuff is off the ground eg on racks, or designed for a wet environment like bikes. You won't be able to change the humidity (will diving hoses and gaskets rot?) short of a ventilation system, which is not doable without power.

 

I am not quite clear about the hierarchy of needs between security (is the garage secure), visibilty (does it matter if people see what is in it?) and other factors  -  can you drill into the concrete to bolt it down, for example or are you relying on weight to hold it down?

 

One solution would be to model it on a secure cycle storage, which are more like a small fenced enclosure with a roof - and are permeable so the draught blows through eg:

https://www.bikedocksolutions.com/recycle-shelter-10-bike-shed

 

But I think the best suggestion I have is what are called "flat pack storage containers", which are used by people who have a garden but poor access. Doors can be in side or end.

 

One of the standard sizes seems to be 2.1m x 2.1m x 3m, which seems to fit the bill. eg

https://www.portablespace.co.uk/shop/flat-pack-units/flat-pack-containers-for-sale

https://www.shippingcontainersuk.com/m28b0s69p2144/Flat-Pack-Containers-3m-self-assembly-green

 

 

 

F

Edited August 13, 2020 by Ferdinand

[Bellefield]

1 hour ago, andyscotland said:

Couple of thoughts:

• Damp might be an issue, as you say there's been one flood before, but also from the concrete, and/or it only takes someone to spill something / have an oil leak or whatever on their car to become at least an annoyance and/or do some damage to the contents / structure.
• The walls might be a bit wobbly with nothing to tie them together / hold them straight at the bottom. Might make it a bit less sturdy around the doors in particular.

You could probably solve those quite cheaply / easily and get a better result without losing too much height by:

• Cover the area with a DPM with enough overlap to bring up the sides a bit
• Then a layer of thin OSB - 9mm should be fine. For a 2200 x 3500 base you'd have 3 boards running side to side.
• Screw the timber wall plate to the OSB perimeter from the bottom before you lay it. Your side-to-side walls can be in one piece along the long side of the sheet, it'd be easier to do the front-to-back as three pieces one on each OSB sheet probably so you can lay them one at a time rather than trying to build the whole floor upside down and flip it after. Once the sheets are in position you can put a second continuous piece of timber over the top to join it together.
• That should be pretty solid already, but to make it really robust you could screw a few bits of plumber's band / thin metal repair plate across the butt joints in the middle of the floor in a few places.
• Build your walls and turn/staple the DPM up the outside of them a suitable distance above the floor.

That should give you a reliably dry, sturdier structure with not a lot of extra cost/effort and only 9mm extra height. Obviously for the best flood etc protection you'd want to continue the wall plate / turned-up DPM across the doorway, but that will give you a step over on the way in. If you'd prefer to have it flat / level I'm sure you'd be fine just stapling the DPM over the edge of the OSB there.

that is a grand idea, and I will go with that!  Thanks - right, now I just need to empty and move the other shed, buy the materials and plan a time to do it ?

[Bellefield]

10 minutes ago, Ferdinand said:

First things first.

 

No it isn't; it's an efficient and appropriate answer to your requirements. 

 

?

 

Second things second.

 

On damp, I think what you want will be OK with whatever method, provided the stuff is off the ground eg on racks, or designed for a wet environment like bikes. You won't be able to change the humidity (will diving hoses and gaskets rot?) short of a ventilation system, which is not doable without power.

 

I am not quite clear about the hierarchy of needs between security (is the garage secure), visibilty (does it matter if people see what is in it?) and other factors  -  can you drill into the concrete to bolt it down, for example or are you relying on weight to hold it down?

 

One solution would be to model it on a secure cycle storage, which are more like a small fenced enclosure with a roof - and are permeable so the draught blows through eg:

https://www.bikedocksolutions.com/recycle-shelter-10-bike-shed

 

But I think the best suggestion I have is what are called "flat pack storage containers", which are used by people who have a garden but poor access. Doors can be in side or end.

 

One of the standard sizes seems to be 2.1m x 2.1m x 3m, which seems to fit the bill. eg

https://www.portablespace.co.uk/shop/flat-pack-units/flat-pack-containers-for-sale

https://www.shippingcontainersuk.com/m28b0s69p2144/Flat-Pack-Containers-3m-self-assembly-green

 

 

 

F

I love this idea, although because of windows, etc, I think I'll stick with a timber shed, tongue and groove cladding and plastic windows

[Ferdinand]

If you want windows they do ones called kiosks or cabins. 

[Nickfromwales]

16 minutes ago, Ferdinand said:

If you want windows they do ones called kiosks or cabins. 

And a resale value too, vs a bespoke DIY timber shed.

[Bellefield]

1 hour ago, Ferdinand said:

If you want windows they do ones called kiosks or cabins. 

 

looks good, I might give it a go, but still leaning towards building something over a couple of days.

[Nickfromwales]

8 minutes ago, Bellefield said:

 

looks good, I might give it a go, but still leaning towards building something over a couple of days.

Assuming freehold, have you checked what you're allowed to store down there? Li ion batteries have a history of going en flambé.....

Edited August 13, 2020 by Nickfromwales