Secure bike-shed - sanity check please...

[Pedropete]

Not strictly speaking a workshop but something to make my workshop a more usable space again. Living without a garage means my workshop is as as much garden shed/garage-substitute as it is an actual workspace. Got some stuff coming up that needs more (and more usable) workspace so planning to re-vamp the workshop and evict the bikes and general shed cr@p to a new structure.

Key requirements are that it needs to be as secure and theft-deterrent as possible as it'll house some reasonably valuable bikes and e-bikes, hence material choice, over-specced framing and small window size. I get that if they want in they'll manage it, but if it makes too much noise and looks like hard work then it may put off the opportunists. It also needs to be constructed in a way that allows relatively easy disassembly as we're planning to move in the next 12-18 months. It will be sited on existing paving, so no option for a brick plinth or suspended ring-beam.

Materials & specs
- Footprint (ground contact): 2400 x 1520mm, not including roof-overhang or wall sheathing & cladding
- Peak height: 2435mm as it's within 2m of the boundary

- Cladding: 15mm rebated shiplap (or feather edge), onto;
- Battens: 19x38 treated, onto;
- Breather membrane: Vent 3, over;
- Wall-sheathing: 11mm OSB3, onto;
- Wall framing: 3x2 treated C24 (no one sells C16 round here)
- Stud spacing: 600mm
- Panel-corners will be tied together with largish lag-screws to resist prying
- Windows: aperture is 150mm high for security, glazed with 4mm float (cos it's cheap and strong enough).
- Tall wall will face a brick garden wall because we're trying block as little light as possible from the back of the house, hence windows being on the short and end-walls.

- Roof covering: Onduvilla tiles (as I’ve just found a pack and a half under the workshop and the pitch is just steep enough), onto;
- Vent 3 membrane/underfelt, onto;
- Roof deck: 11mm OSB3, onto;
- Roof structure: 4x2 treated C24
- Roof overhangs: 100m (end-wall) and 250mm (door wall)
- Roof will be tied to the blocks visible on the long wall top-plates with HD pockethole screws: 1 from each side, staggered vertically

- Flooring: 18mm OSB3 onto...
- Sub-floor: 3x2 treated C24, onto...
- Bearers: 25x50mm recycled PE battens (acting as DPC)

- Door: framed and braced with 3x2 treated C24, covered with Vent 3 and 15mm treated T&G

Questions/concerns etc.
I'd be really grateful for some experienced input/suggestions/alternatives on the attached pics (2D Sketchup exports) with regard the above spec and the following key requirements/concerns:

Q. Planning to fit a long-throw lock (GateMate or similar). Would like multi-point locking but not found anything suitable in the EU. Ideas?

Q. While the plastic bearers should prevent most rising damp issues, I'm wondering if Vent 3 between the OSB floor and sub-floor (exterior side facing down) would help allow any moisture to move downwards but prevent anything evaporating up into the flooring?

Q. Any thoughts on best way to cover the roof/apply facias? Never done a pent roof before so learning on the go.

Q. There's a 20mm gap between top of the walls and underside of the roof deck to allow high-level ventilation but what's the best way to close in the soffits, allowing airflow but preventing bugs from making a home?

Q. While I'd expect the sheathing to adequately brace the frame, the shed will be in a relatively exposed location. Should I consider bracing the frame to resist racking in high winds?

Thanks in advance,

Pete.

 

[Inspector]

I wouldn't go to all that work if you are moving in a year or two. I would get a little shipping container. When you are ready to move you can drag it onto a trailer or tilt deck tow truck and haul it away. While not break-in proof, pretty close. You can always put up a trellis or fence with lath around it to make it a bit less of an eyesore :roll: to the neighbours. Plant Scarlet Runner Beans around it and it will be even better concealed.

https://www.containercontainer.com/small-containers

Pete

 

[Pedropete]

I wouldn't go to all that work if you are moving in a year or two. I would get a little shipping container. When you are ready to move you can drag it onto a trailer or tilt deck tow truck and haul it away. While not break-in proof, pretty close. You can always put up a trellis or fence with lath around it to make it a bit less of an eyesore :roll: to the neighbours. Plant Scarlet Runner Beans around it and it will be even better concealed.

https://www.containercontainer.com/small-containers

Pete

Thanks - reasonable suggestion. Did look at containers - along with Asgard and Trimetals 'security' sheds - but the dimensions on all of them are too long and/or wide and with insufficient headroom when specced to take the bikes we need to store. Rationale for a pent roof was to get sufficient height on the tall wall to hang one bike above another. One of the bikes is a cargo bike and too long (and heavy!) to be hung against a wall by its front wheel. Not that much work either: have built bigger structures than this in a long weekend before but not with a pent roof, so am allowing an extra day for faffing.

Cost is also a consideration, with this costed at around £650 so far subject to the cladding used. It'll also fit in the back of a luton van along with all the other garden stuff when we move, so more cost effective for transport as opposed to something that would need an additional dedicated vehicle on moving day.

 

[MikeG.]

You can leave out the breather membrane, as it does nothing.

You don't say the size of your building. If it is reasonably small (say under 10 sq metres) you could easily make it from 2x2s rather than 3x2s. I'm struggling to understand why you would want windows in a bike shed. That's just an invitation for thieves.

Having saved you a bit of money, I'll now take some off you, because the roof deck needs to be 18mm thick.

The sheathing board is way stronger than any bracing, so you've more than enough to prevent racking. Keeping it tied down to the ground is a bigger issue. You also know of course that I'll tell you to put the building on a plinth, and there are at least two ways to do this in the links in my signature.

Ideas for locking include having a visible strong external steel strap across the door, and even better if this has a mystery method of opening rather than a vulnerable padlock (which will hold up a thief for about 5 seconds). Still on your list of questions, the best way to cover the roof is with EPDM ("rubber"), and there are lots of proprietary edge details available from whichever supplier.

 

[MikeG.]

......... Did look at ....Asgard and Trimetals 'security' sheds......

Are these steel sheet sheds? If so, they are a nightmare for bikes. They'll drip condensation through the entire winter. It takes an awful lot of work to make them suitable.

 

[Pedropete]

Extremely helpful input, thank you Mike.

leave out the breather membrane, as it does nothing.

Completely dump the membrane? Even with OSB for sheathing instead of ply? Not arguing the toss, was just a bit worried about the OSB swelling, particularly the lower edges.

You don't say the size of your building... you could easily make it from 2x2s. I'm struggling to understand why you would want windows in a bike shed.

Footprint is 2400x1520 in contact with ground. Needs to be 3x2 is it'll have at least one heavyish bike hung high on the taller wall and don't want to risk it bowing outward (externally) below the suspension point. And, it's a garden shed as well as bike shed unfortunately so windows are to admit sufficient daylight for basic bike maintenance and general shed rummaging without needing power for lights. They're small though (150mm high) so not a viable point of entry, and, with 3x2 framing, shouldn't offer a way to force the wall panel apart. If they're willing to make that much noise then it's a lost cause anyway.

... roof deck needs to be 18mm thick.

Well spotted! Thank you.

The sheathing board is way stronger than any bracing... keeping it tied down to the ground is a bigger issue. You also know of course that I'll tell you to put the building on a plinth...

Has to sit on existing paving for now but it'll be tied into anchors resin-set into same, so should stay where it's supposed to.

Ideas for locking include having a visible strong external steel strap across the door, and better if this has a mystery method of opening...

Will be using heavy duty hinges, coach-bolted through the frames with backing plates. and possibly some hinge claws if I can find some. As for locks, the bar is a good idea. Will look into it.

... best way to cover the roof is with EPDM

Looked at EPDM but the cost is £250+ with trims and adhesive, as opposed to poly-backed felt at £30.
EDIT: just discovered a spare pack and half of Onduvilla tiles and some verges under my workshop. That’s 2/3 of the needed coverage so will be using this instead. Just need to figure out how enclose the open tile-ends at the high end of the pitch.

...Asgard & Trimetals sheds... are these steel sheet sheds?

Yes, hot-dipped steel, drippy as hell - even with increased ventilation - and 'kin ugly. Only appeal was assembly time and the guarantee but you can't hang anything heavy on the walls and they're not tall enough so a non-starter anyway.

 

[MikeG.]

...... Completely dump the membrane? Even with OSB for sheathing instead of ply?........

You can put it in if you want, but with the air gap behind the boards the OSB should never be wet, other than at the bottom with it sitting on concrete. Such a pity. Leaving out a plinth turns this into a temporary structure, taking decades off its life.

 

[Pedropete]

You can put it in if you want, but with the air gap behind the boards the OSB should never be wet, other than at the bottom with it sitting on concrete. Such a pity. Leaving out a plinth turns this into a temporary structure, taking decades off its life.

Bottom edge of the sheathing will over-sail the OSB floor-edge and timber sub-floor by 50mm, ending at 60mm clear of the ground. Cladding will run a further 30mm past that ending up 30mm from ground. I designed in 3x2 for the sub-floor specifically to get that clearance.

In which case then, I'll leave the membrane out. Thank you again. When it gets to its new home it'll go on an appropriate base, I promise!

 

[Myfordman]

You could always make your plinth from concrete lintels that you could take with you when you move?

 

[samhay]

......... Did look at ....Asgard and Trimetals 'security' sheds......

Are these steel sheet sheds? If so, they are a nightmare for bikes. They'll drip condensation through the entire winter. It takes an awful lot of work to make them suitable.

We have an Asgard bike shed. I won't disagree about it being fugly, but condensation is not nearly as bad as I thought it would be, and we're on the side of the Pennines so not in the driest part of the county.
They are likely no good for the OPs requirements (hanging heavy bikes), but work ok if you are happy to lean bikes against each other. There are a lot of very expensive bikes stored in them as they seem to be recognised by insurance companies as a reasonably secure means of keeping one's bike(s) stored outside. The main deterrent to break in is probably how much noise it would take to pop them open.

OP - before you finalise details of your build, it may be worth giving your insurance company a call to see if they would cover your bikes if they were stolen from you new shed.

 

[Pedropete]

You could always make your plinth from concrete lintels that you could take with you when you move?

They'd still need fixing in place, which would damage the patio far more than the anchors I'm planning to use. Would also raise the peak height above the 2500mm limit for being within 2m of a boundary.

 

[MikeG.]

...... Would also raise the peak height above the 2500mm limit for being within 2m of a boundary.

No, you just make your timber walls 4 or 6 inches shorter, whatever, to allow for the difference.

 

[Pedropete]

No, you just make your timber walls 4 or 6 inches shorter, whatever, to allow for the difference.

That would drop the door header too low and need the internal headroom to hang one bike above another on the tall wall. I appreciate and agree with your concerns but it can't go on a plinth for now. As and when it gets moved it will go on a more suitable base. Always helpful to be challenged though, so thank you.

 

[MikeG.]

......That would drop the door header too low........

Header? You've been watching too many American Youtube clips. It's a lintel here. :wink:

And no, it doesn't affect anything height-wise. You're effectively cutting X inches off the bottom of the walls and replacing them with concrete, with everything else remaining precisely where they were.

 

[Pedropete]

We have an Asgard bike shed. I won't disagree about it being fugly, but condensation is not nearly as bad as I thought it would be... They are likely no good for the OPs requirements (hanging heavy bikes), but work ok if you are happy to lean bikes against each other. There are a lot of very expensive bikes stored in them as they seem to be recognised by insurance companies as a reasonably secure means of keeping one's bike(s) stored outside. The main deterrent to break in is probably how much noise it would take to pop them open.

OP - before you finalise details of your build, it may be worth giving your insurance company a call to see if they would cover your bikes if they were stolen from you new shed.

Good to know about the condensation, particularly in a climate like yours. Some relatives are looking at one so will pass your comments on.

The noise factor is definitely a deterrent but a surprising number have been broken into with rapid brute force style attacks, where speed is more important than noise made. Grinders, long pry-bars and gas-jacks seem to be effective. Insurers like them because they're a known quantity, so easier to rate than the various methods you or I could use to build a more secure structure.

Our insurer (Direct Line) specify only that any outside structure the bikes are stored in should be 'key-locked', i.e. not padlocked. they don't even specify anchoring to a hard point. Some specialist bike insurers however specify a rated structure and 'Sold Secure Gold' locks into fixed internal anchors, and charge more for the privilege. Go figure.

 

[MikeG.]

We have an Asgard bike shed. I won't disagree about it being fugly, but condensation is not nearly as bad as I thought it would be... They are likely no good for the OPs requirements (hanging heavy bikes), but work ok if you are happy to lean bikes against each other. There are a lot of very expensive bikes stored in them as they seem to be recognised by insurance companies as a reasonably secure means of keeping one's bike(s) stored outside. The main deterrent to break in is probably how much noise it would take to pop them open.

OP - before you finalise details of your build, it may be worth giving your insurance company a call to see if they would cover your bikes if they were stolen from you new shed.

Good to know about the condensation, particularly in a climate like yours. Some relatives are looking at one so will pass your comments on. ......

One of the guys on Woodhaven 2 has one of these and has had to move his bikes out for the winter as they were rusting and growing mould. We used one as a temporary document store at a former commercial practise I worked for when we moved premises, and had to employ a professional document restorer at vast cost to sort out the sodden pulp of papers that resulted. Although Samhay has a different experience I'd certainly suggest caution in recommending steel sheds for bike storage.

 

[Pedropete]

One of the guys on Woodhaven 2 has one of these and has had to move his bikes out for the winter as they were rusting and growing mould. We used one as a temporary document store at a former commercial practise I worked for when we moved premises, and had to employ a professional document restorer at vast cost to sort out the sodden pulp of papers that resulted. Although Samhay has a different experience I'd certainly suggest caution in recommending steel sheds for bike storage.

I'd imagine that through-flow of air, and therefore location of the shed, has a lot to do with how severe the condensation is. As already stated, they wouldn't be my first choice. The relatives in question need something to go in their font garden though (no side-access), and these are the only insurable options for that location in the area they live in, and that's with none of their bikes being worth more than £500.

 

[Woody2Shoes]

I have an asgard storage unit, but it's inside an existing shed. I don't find condensation a big problem, but anything stored in there does get 'winterized' before it goes in - if of any significant value and/or vulnerability to rust.
Cheers, W2S

 

[Richard_C]

You could think about some secondary security. I know a couple of people near me who have bike sheds with a short steel post/hoop coming up through the floor, one is cemented into a hole in the ground the other has a big flat plate bolted under the floor so just the post sticks through - easy to fit when you are building it. Bikes get locked to it, the chain or cable never goes out with the bikes so it can be as heavy as you like. Doesn't stop break ins, but thieves likely to go elsewhere once they see it.

You could get a battery powered LED motion sensing light over the door, I have one round by the bins (I can't tell the blue bin from the black one when its dark), cost me less that £10 for a pair and the AA batteries last for ages. Then maybe add an old webcam or a hole that might be a webcam with an appropriate label, no need to wire it to anything. Nothing is 100% secure but your shed need to look more of a challenge than one down the road.

 

[FatmanG]

I have secured my shed with 2 bars of unistrut 41mm x 41mm withe brackets coach bolted through the concrete walls I have an alarm and a sign in bright yellow saying this shed is alarmed. I'm hoping its enough to make the other sheds on my estate far more appealing. The total cost on security is only £40.00 the unistrut is bloody thick I know nothing is impenetrable but this is pretty good.
Glenn