It comes by many names Interclamp, guard rail etc... but you probably know what I mean. I've been planning for some time to try out a garden structure and I thought I'd share what I'm learning along the way. I think the hardest part was figuring out how to put some kind of roof on and I feel like I kind-of botched this but couldn't think of a better way. Love to hear feedback from other people who've attempted similar. Here is my idea to come up with a play-house for children.
First some fun facts
A KEE KLAMP fitting (size 5 to 9) can support an axial load of 900 kg per grub screw with the grub screw tightened to a torque of 39 Nm. OK I'm not using this brand but ratings are similar. Take note: This is presumed to be with NEW grub screws. Once you use them, best save them for the non-critical elements of whatever structure you're putting together, perhaps horizontal tubes. In my case I managed to get everything right first time.
The structure will wobble if not cross-braced, but not as much as standard scaff fittings. If this bothers you, either introduce cross-bracing explicitly with a 45 degree element or through your design, e.g. put a wall in to provide stability instead.
The founds
There is, unfortunately virtually nothing on the internet to help the DIYer in this kind of endeavour, so I've probably over-engineered the start of the project, which is the 'foundation'.
This is a metre-deep 6 inch hole cut with a fence post auger. The tube I put down it had both ends blocked with e-foam which I left curing overnight in some vague attempt to avoid water ingress. The net is awash with opinions about how to keep a steel pole in the ground for long periods of time. Lucky for me I'm using galvanised tube, and I don't really care if it only lasts 10 years by which time the kids will probably have lost interest.
A couple of bags of postcrete in each hole kept the tube upright.
Choose your fittings wisely
6x 2m tubes upright in the ground left me plenty of time to decide on a design. It rapidly became clear that design with kee klamp is a very tricky business. Unlike normal scaff which you can just shove on anywhere, the kee-klamps have to slide on the ends. If you're not careful you can come up with a design where it needs to kind-of float in the air for you to put it all together.
There are some annoyances with certain parts that are missing. For instance, there is a three-way elbow 128d, great for a corner
https://www.actavodirect.com/key-clamps/product/clamp-3-way-elbow-128d/
But if you want that to meet with a four-way equivalent of the same thing in the middle of a 'wall' the only option is
https://www.actavodirect.com/key-clamps/product/clamp-side-out-tee-176d/
If you look closely, if you want to use such an arrangement at the eves and your vertical poles are all the same height, the heights will be wrong, because the 3-way elbow sits higher up, just above the vertical pole. There is no '4-way elbow' that I could find.
I decided that it was much better to just stick to fairly standard knee and T-shaped fittings than try to use some of the more exotic parts. T fittings for supporting horizontal elements seemed a good way to get maximum axial load (2 grub screws), even if I wastn't going to need it for my application
Checking the levels
Forget about using a scaffolder's level to check horizontal. Maybe you're lucky and got every single tube dead straight but more likely not. You'll measure it at one end and then the other will dip down or curve up. In this case I used a laser level but I would have used a 2 by 4 and a spirit level if I didn't have it.
Half-couplers are great for positioning. Just position the half-coupler below the tee fitting, but tighten this coupler with the tee in place resting above it because the coupler doesn't have a regular top surface. It's the position of the tee that matters, not the coupler. Then when you come to slide the cross-member with a tee on each end down the vertical tubes it's a one-man job. Just tighten to 40Nm torque without any worries it'll move about.
Protruding inside
As stated previously, take a lot of care about how far into the fitting you'll allow the tube to go. Best to not go into the fitting on the vertical, as shown, because it's easier to measure accurately the height. Leaving the innards clear gives you more scope on the length of the horizontal tube which is harder to measure.
In short, remember what I said about bent tubes. The measurement between the tops of the poles will diverge from your carefully positioned bases. You could try to bend the tops a bit, but those kind of antics tend to be a fool's game.
Holding it in place
Sometimes you have to resort to conventional scaff as bracing while putting it together. If you've got 2-3 people maybe you can manage without.
Sticking with Tees
I've chosen a multi-level design partly because it's more interesting but also because it's a nice way of sticking with the Tees. I avoid a long, wobbly span, or weak 'side out tee' arrangement in the middle this way.
The flooring
Untreated scaffold boards are great for this sort of thing. Non-slip even in the wet and cheap. I may put something on the ends but that will probably be it. It remains to be seen how they last, but they are off the ground. We'll just have to see.
According to scaffolding rules they're supposed to be supported every 1.2m. I've gone 1.5m but I've put a binder underneath to hold the centers together. It's for kids but even with me jumping on it it's very sturdy (sorry don't have pictures of the finished article ATM).
The roof
The roof is a curious design because not only is the building L-shaped, but I wanted max headroom due to permitted development restriction of 2.5m. I've opted for a ridge beam but it sits across three horizontal tubes for support. In any case I didn't have a long enough bit of ridge timber to do that all in one piece. I should probably get a drone to show a better pic:
I wanted the OSB joined exactly at the ridge, so I clamped blocks to slide it into place and worked from top to bottom. I don't know how normally people do this, it's my first shed roof.
Pitch is 15 degrees or thereabouts.
The ridge beam is supported off the scaff tube by three structures fashioned from 18mm ply in two planes which are designed to slide around a bit at the bottom for positioning the ridge in the right place.
They provide very strong support in the horizontal directions. It's possible they can be removed or reduced once the roof is finished.
First some fun facts
A KEE KLAMP fitting (size 5 to 9) can support an axial load of 900 kg per grub screw with the grub screw tightened to a torque of 39 Nm. OK I'm not using this brand but ratings are similar. Take note: This is presumed to be with NEW grub screws. Once you use them, best save them for the non-critical elements of whatever structure you're putting together, perhaps horizontal tubes. In my case I managed to get everything right first time.
The structure will wobble if not cross-braced, but not as much as standard scaff fittings. If this bothers you, either introduce cross-bracing explicitly with a 45 degree element or through your design, e.g. put a wall in to provide stability instead.
The founds
There is, unfortunately virtually nothing on the internet to help the DIYer in this kind of endeavour, so I've probably over-engineered the start of the project, which is the 'foundation'.
This is a metre-deep 6 inch hole cut with a fence post auger. The tube I put down it had both ends blocked with e-foam which I left curing overnight in some vague attempt to avoid water ingress. The net is awash with opinions about how to keep a steel pole in the ground for long periods of time. Lucky for me I'm using galvanised tube, and I don't really care if it only lasts 10 years by which time the kids will probably have lost interest.
A couple of bags of postcrete in each hole kept the tube upright.
Choose your fittings wisely
6x 2m tubes upright in the ground left me plenty of time to decide on a design. It rapidly became clear that design with kee klamp is a very tricky business. Unlike normal scaff which you can just shove on anywhere, the kee-klamps have to slide on the ends. If you're not careful you can come up with a design where it needs to kind-of float in the air for you to put it all together.
There are some annoyances with certain parts that are missing. For instance, there is a three-way elbow 128d, great for a corner
https://www.actavodirect.com/key-clamps/product/clamp-3-way-elbow-128d/
But if you want that to meet with a four-way equivalent of the same thing in the middle of a 'wall' the only option is
https://www.actavodirect.com/key-clamps/product/clamp-side-out-tee-176d/
If you look closely, if you want to use such an arrangement at the eves and your vertical poles are all the same height, the heights will be wrong, because the 3-way elbow sits higher up, just above the vertical pole. There is no '4-way elbow' that I could find.
I decided that it was much better to just stick to fairly standard knee and T-shaped fittings than try to use some of the more exotic parts. T fittings for supporting horizontal elements seemed a good way to get maximum axial load (2 grub screws), even if I wastn't going to need it for my application
Checking the levels
Forget about using a scaffolder's level to check horizontal. Maybe you're lucky and got every single tube dead straight but more likely not. You'll measure it at one end and then the other will dip down or curve up. In this case I used a laser level but I would have used a 2 by 4 and a spirit level if I didn't have it.
Half-couplers are great for positioning. Just position the half-coupler below the tee fitting, but tighten this coupler with the tee in place resting above it because the coupler doesn't have a regular top surface. It's the position of the tee that matters, not the coupler. Then when you come to slide the cross-member with a tee on each end down the vertical tubes it's a one-man job. Just tighten to 40Nm torque without any worries it'll move about.
Protruding inside
As stated previously, take a lot of care about how far into the fitting you'll allow the tube to go. Best to not go into the fitting on the vertical, as shown, because it's easier to measure accurately the height. Leaving the innards clear gives you more scope on the length of the horizontal tube which is harder to measure.
In short, remember what I said about bent tubes. The measurement between the tops of the poles will diverge from your carefully positioned bases. You could try to bend the tops a bit, but those kind of antics tend to be a fool's game.
Holding it in place
Sometimes you have to resort to conventional scaff as bracing while putting it together. If you've got 2-3 people maybe you can manage without.
Sticking with Tees
I've chosen a multi-level design partly because it's more interesting but also because it's a nice way of sticking with the Tees. I avoid a long, wobbly span, or weak 'side out tee' arrangement in the middle this way.
The flooring
Untreated scaffold boards are great for this sort of thing. Non-slip even in the wet and cheap. I may put something on the ends but that will probably be it. It remains to be seen how they last, but they are off the ground. We'll just have to see.
According to scaffolding rules they're supposed to be supported every 1.2m. I've gone 1.5m but I've put a binder underneath to hold the centers together. It's for kids but even with me jumping on it it's very sturdy (sorry don't have pictures of the finished article ATM).
The roof
The roof is a curious design because not only is the building L-shaped, but I wanted max headroom due to permitted development restriction of 2.5m. I've opted for a ridge beam but it sits across three horizontal tubes for support. In any case I didn't have a long enough bit of ridge timber to do that all in one piece. I should probably get a drone to show a better pic:
I wanted the OSB joined exactly at the ridge, so I clamped blocks to slide it into place and worked from top to bottom. I don't know how normally people do this, it's my first shed roof.
Pitch is 15 degrees or thereabouts.
The ridge beam is supported off the scaff tube by three structures fashioned from 18mm ply in two planes which are designed to slide around a bit at the bottom for positioning the ridge in the right place.
They provide very strong support in the horizontal directions. It's possible they can be removed or reduced once the roof is finished.
But thanks for the link to Doughty Engineering.
