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Build A Secure Bike Shed

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Build A Secure Bike Shed

There’ll be no stealing of these ‘ere bikes.

Having looked around, I was deeply unsatisfied with the options available to me with regards to a decent bike shed. As is often my motivation for these sorts of things, I figured I could make something much better for much cheaper. I think I succeeded. This shed not only looks slick (in my opinion) but it’s sturdy and most importantly, keeps our bikes very secure.



The reason this bike shed is so secure is all down to the base. The bikes are chained to a ground anchor which is bolted to a 4-inch thick concrete slab. Nothing will make bikes completely unstealable but this will get you most of the way. In order to make the foundation, I first constructed a sort of formwork frame. I say sort of because normally formwork is removed but I plan to leave it in place.

Concrete slab falsework
It’s important that you get the top of this frame level as it will help form the floor of your shed.

I was fortunate enough to have paving down where I wanted my shed. If you don’t have a solid base on which to pour your slab this is something you would need to consider. On soft ground, this could be achieved by digging a trench of about 6 inches around the perimeter and pouring a concrete footing. Make your formwork big enough to accommodate the bikes you wish to store. Mine was 1800mmx950mm. Use either wooden wedges or pieces of stone to shim the bottom of the frame and make it level across the top.


Use damp proof membrane (DPM) to line the formwork. I cut the piece roughly to size leaving a generous margin on all sides, then set about fitting it into the frame. It’s a bit like wrapping a present but from the inside. Make sure to push the membrane down into the corners otherwise it will put unnecessary stress on the formwork when you fill it with concrete. This lining serves two purposes; firstly, it prevents the slab from absorbing moisture from the ground and secondly, it creates a neat container to pour your concrete into. I used heavy duty staples to fix the DPM to the top face of the timber pieces, clout nails or something similar would also work. Make sure you don’t staple the sheet below the top edge of the frame, it will defeat the purpose of having a membrane if it has holes in it! I left the remainder of the sheet covering the floor in front of the formwork, this will help prevent staining the surrounding area with spilt concrete.


I’ll be honest, mixing concrete is one of my least favourite things in building projects. It’s hard work and if you’re not careful you can hurt yourself doing it. I, unfortunately, gave myself a hernia during this part of the project. Try not to do that. My advice is to hire a cement mixer but if you’re saving the pennies doing it with a paddle mixer will work, just mind how you go.

Mix the concrete in a wheelbarrow or large bucket like the one shown. A wheelbarrow would have made tipping it into the formwork easier, to be honest. Add 3 parts sand, 3 parts gravel and 1 part portland cement to your mixing container. Dry mixing the concrete a bit before adding water will reduce the overall mixing time. Add enough water that the mixture becomes workable; don’t add too much, it weakens the final product. A dryer mix will typically be stronger but harder to work. Finding the balance between workability and strength is the key. If you can achieve something similar to the consistency of peanut butter, you’re in the right ballpark.


Pour each mix into the formwork, make sure to get it right into the corners and remove any air pockets. Start at one end and partially level the concrete before each new mix, this will help you estimate how much more you require as you go along. Mixed concrete isn’t a particularly easy thing to dispose of. Keep mixing and pouring until you have filled the base.

It is important that you get the top of the concrete level at this stage. Once it goes hard you’ve got no chance… obviously. Place a straight piece of timber across the top faces of your formwork and wiggle it around until it lies totally flat. Work the timber across to one side of the formwork with a sawing motion. This levels the concrete surface as you go. You’re aiming to smooth off any high points but also take care not to leave any areas where concrete doesn’t reach the top edge of the frame.

Once the surface is level you can add extra texture by see-sawing the timber from one side to the other. This creates a kind of “crinkle-cut” surface making the concrete less slippy if it gets wet. After this, you simply need to leave the concrete to fully set. Drying times vary based on climate and mix ratios but 2-3 days should get you close enough to continue work. If it’s going to be very hot then cover the mix to prevent cracking. Never pour concrete if it’s going to drop below zero before it dries!


This frame ended up being a little over-engineered (as do many of my creations). You could probably scale back the amount or thickness of timber if you’re trying to keep costs to a minimum. However, it is strong and has stood resolute though all of Yorkshire’s worst weather for 2 years now without even a hint of a wobble. So… you choose.


I started with four 3″x3″ posts fixed to the concrete base and frame by inserting them into post anchors and fixing with thunderbolts and screws. I left space between the post and the concrete edge to fix the rest of the framework in such a way that the cladding will overhang the edges. This will ensure rainwater runs off onto the ground and not onto the concrete slab.


Using 3″x2″ treated timber, I cut and laid out the pieces that will make the side profile of the shed. Don’t forget to put a pitch on the roof, somewhere between 15 and 20 degrees works pretty well. Laying out like this before you screw things together makes it easier to ensure everything is square and the correct length before it’ too late. Use decent wood screws suitable for outdoor use – ones that won’t rust. There’s no point using chunky timber if it’s not fixed well so don’t skimp on the screw length either. The longest piece will determine the overall height of your shed I went for just over 6′.

It’s easiest to clad the framework before fixing it place. It’s like a miniature pre-fab, where the walls are made as complete panels and then fixed together at the end. I used treated shiplap timber with about a 30% overlap. If you’re worried how it’ll look on a hot day then I’d recommend some sort of adhesive in the overlaps. When the sun gets on thin timber like that it curls in the direction of the heat, ours looks like it’s ruffled its feathers on a sunny day.

Finally, attach the framework to the posts from the inside with some decent length coach screws.

Rear & Roof


I didn’t take the best pictures of this stage, to be honest. I used more treated 3″x2″ to brace across the front between the posts at the top and twice on the back; one at the top and one halfway down. I then used exterior grade plywood to skin the back face. Before I put these up I covered them in DPM. This is an ugly but effective way to ensure the water that runs off the roof at the back doesn’t saturate the plywood. It didn’t matter how it looked as it backs up against a wall but if yours doesn’t then I’d use more shiplap cladding here.

Top tip: Don’t try and move sheets of plywood yourself if it’s windy. I did and ended up dislocating my thumb.


For the roof, I again used exterior grade plywood. Cut the plywood leaving a slight overhang, it doesn’t need to be very big, just enough to avoid rain dripping into the structure. I fixed two thin strips along the short edges and one along the front edge to help channel rainwater.

Roofing felt is best fitted on a warm day. Roll out what you need and leave it in the sunshine for about an hour to warm up. This makes for a much easier job when you’re pulling and folding the corners. If you try to do it on a cold day you’re likely to split the felt. Cut the felt oversized, enough that you will be able to comfortably fold it over the sides. Coat the plywood in bitumen to help it adhere to the felt. Use a cheap brush and get rid of it afterwards, bitumen is horrible stuff. Fold the felt under the front edge and fix it with clout nails, pull it tight across the surface and do the same on the back edge. Then, a bit like wrapping a present again – but this time not inside out – fold the short edges under and fix those too.

Place and centre the roof, making sure your overhangs are even, then fix it from underneath.


I opted for an Oxford ground anchor, designed for motorcycle security. They’re pricey but pretty much impossible to break without some serious time, tools, effort and noise. To complement this I also bought an Oxford chain, again money well spent. All the instructions for fitting it came in the box but I’ll outline it here anyway.

First, place the anchor on the ground and check the position with the chain you bought and the position you want to store your bikes. Mark the position of the holes and use a hammer drill to make holes big enough to receive the concrete fixings. Tap in the fixings and bolt both layers of the anchor down. Finally, tap in the supplied ball bearings and anti-tamper caps to prevent the bolts being removed by any would-be bike snatchers.

During this stage, I also added a timber bracket and hook to hold one end of the chain. This means you don’t have to hold the heavy chain up while fastening and unfastening the lock. It’s a small detail but makes actually using the lock much easier.

Doors and Lock

For my doors, I used the same treated 3″x2″ I used for the frame. I went for three hinges, though this may have been a little overkill. It gets pretty windy down the back and I wanted it to be able to withstand accidentally swinging wide open. The most important thing when making doors or gates this way is the diagonal pieces. They give all the strength and without them, your door will certainly sag. Nobody likes a saggy door. Don’t skimp on screws and if you think it needs it, add some strength with metal brackets and plates.

The cladding on the front of the doors is vertical because I liked how it looked, you could do it either way really. I wanted the front to look seamless so I was careful to work out the spacing and make sure the pieces were symmetrical on both doors. I used the same treated shiplap timber as I did for the sides.

When you choose your latch, make sure you get one that has a security bolt. Otherwise, someone can simply remove the fixing screws and totally bypass the lock. Position and fix this once both your doors are hung to ensure good alignment. If you can… wait until the doors have settled a little under their own weight, that way you can have it operating super smoothly.

Store all the things

Ignore that seem line in the middle of the roof fascia. It’s not really there, you’re seeing things. Are your eyes OK?

Sorted. To be honest, it really needs a couple of extra pieces of cladding to hide the hinges. I did intend to do it but… well, I never did because I like how they match the latch. This project was nearly two years ago now and the shed has needed very little maintenance. The door blew shut in the wind one day and broke the central piece of the cladding so that’s been repaired and reinforced, but otherwise, it’s stood up to the weather beautifully.

Full plans available



A lifelong fan of making and breaking things. If you can do it yourself, why wouldn't you?

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