Freestanding 'carport' made from scaffolding?

[Yerptie]

Hello everyone,
This is my first post after reading a few threads on these forums, courtesy of a popular search engine's results for my query terms.

I'm looking to build a carport structure.
Approximate total area being 2.6 meters wide by 10 meters long.
Maximum height over property roof tiles less than 3 meters.
Eaves height approximately 2.4 meters.
So within constraints to not requite planning permission.

I'd prefer not to attach to the property walls as like the few cranked posts with bespoke carport designs. However, I don't completely object to some tie-ins if necessary.
Had experience with a lean-to design before and it was stifling hot in warmer weather and with cooking having no where else to vent from the kitchen. This design reaches above the gutter (allowing access for clearing debris), and being just above the top cement line of the first hip tile. Hot air should be able to vent up and out without too much restriction.
The property eaves come forward as does the facia and guttering, hence the gap between the wall and the nearest line of 'posts'.

The roof being:
Either 10 mm twin wall or 16mm triple wall polycarbonate roofing sheets, probably 700mm centres if 10mm, maybe wider if the later.
Snap down glazing bars atop ~50mm wide x ~50-75 mm high/thick treated wooden 'rafters'.
Around about a 10° slope (17.6 cm in 100 cm) per recommendations (5° min, pref. 10°).

Under structure:
I was considering using aluminium 6082 T6 (no rust/rot and light weight) 48.3mm (4.4mm) scaffold tubes to construct the entire framework with either KeeKlamp-style fittings (like the path railings and cycle blockers in public footpaths) or some other scaffold support clamps. Then using double-sided fixing brackets (look a bit like the Greek letter omega) to fix the wooden 'rafters' to.

Vertical 'posts' ~2 meters spanning (away from property wall), and 1.85 meters apart (fence panel + 1 inch for concrete post).

Concrete footings (~30 cm x ~30 cm x ~60 cm deep) poured and levelled, with 'railing' baseplates (2 hex screws, 2 bolt down holes) being used to support the upright 'posts'. The baseplates seem like they are advised for climbing frames as well as railings, so I'd expect them to be pretty strong.

Double-sided fixing brackets attached to the (4) tubes that run lengthways atop the angled pieces.
A very dirty representation courtesy of my limited time in FreeCAD.

Am I utterly mad? Is this a workable project?
I'd prefer not to use wood as it needs treating and more long-term care.
Aluminium seems preferable, but is it strong enough? I haven't worked with the stuff, but how much does a 2 meter 48mm Al tube bend?
Whilst a 20 ft /6 meter Al tube is only 10 kg, I think it's rather unwieldy. I could do 6 m and 5 m lengths, joined and cut to absolute size, but I am considering working with 3 meter length exclusively and offsetting with adding additional bracings and/or 'joiner' couplings.

Thanks for suggestions, comments and any feedback.

 

[mattylad]

I'm glad I'm not your neighbour!

Yes you sound like a nutter

 

[Tigercubrider]

I use a lot of scaff and kee clamp but yours seems like a ton of metal?
My mate’s carport was there when he moved in and is basically UPVC posts in fence post sockets.
I can’t remember if the roof structure is upvc or timber.
The roof is corrugated plastic, replaced once in about 25 years

 

[Yerptie]

I'm glad I'm not your neighbour!

Yes you sound like a nutter

It's OK. We get to look at the neighbour's apex garage roof that also blocks quite a bit of light in the colder parts of the year. There isn't that much that would be sticking up above the fence line to be honest - their ground level is higher than ours thus making the fence that bit taller in effect.

I use a lot of scaff and kee clamp but yours seems like a ton of metal?
My mate’s carport was there when he moved in and is basically UPVC posts in fence post sockets.
I can’t remember if the roof structure is upvc or timber.
The roof is corrugated plastic, replaced once in about 25 years

So, are you suggesting that I probably don't need need all of the support posts, or generally there is just too much metal work?
I am struggling to find any canopy kits that aren't lean-to types with the top bar fixed to the property brickwork under the gutters/soffits. Definitely need to to go over and above the gutter to vent more heat and allow for gutter maintenance.

Had experience with the corrugated plastic before, creaky bendy stuff. At least with polycarbonate multi-wall there aren't going to be any screws through the 'glazing' panes, as the fixings are at either side of the sheet.

What kind of span is 48.3 mm x 4.4mm 6082 T6 aluminium tube good for? The answer depends on load and it's position, as well as how either end if fixed. Daft question

 

[Letsgetitdone]

Have you considered just making it out of timber? I think you mention making the roof rafters out of timber, so why not the whole thing. I know you mention rotting/more care etc but if you are using treated timber and paint the structure every few years, then it should last. I reckon you would end up painting those scaffold poles eventually anyway. Unless you've got access to a load of cheap scaffold poles I'm not sure why you would do it this way.

 

[RandomGrinch]

I am struggling to find any canopy kits that aren't lean-to types with the top bar fixed to the property brickwork under the gutters/soffits.

Silly question, but have you tried searching for "freestanding carports"?

Examples here...

Freestanding Carports - The Canopy Shop

Freestanding carports are a stylish way to cover your vehicle without having to worry about fixing to a supporting wall. Our free standing carports are the cost effective choice to keeping your car, van or motorbike sheltered from the weather all year round. Made from rust resistant aluminium...

thecanopyshop.co.uk

Even if you have, the images will give you an idea of the minimal amount of structure involved.

 

[Koolpc]

When finished, remember to put yellow foam protection on the uprights, hang a high vis vest on it and put a radio on hanging from one of the poles!

 

[cdbe]

I would use cheaper galvanised steel scaffolding tube, but only for the vertical structure. Use treated 4x2 for the roof/horizontal elements - the regularised timber is presentable (not like rough sawn stuff and can be nicely painted or stained) - it'll all be under cover and well ventilated so won't rot - and easy to fix the roof covering to. I wouldn't try bolting the tubes to the ground, just set in concrete like fence posts, have them a bit longer than you need them so you can cut the tops level. The baseplate things you mentioned can be used upside down to neatly fix your "wall plates" to the tops of the tubes.

Don't quote me on this, as I only tried it briefly a few years ago, but I'm pretty sure that 50mm pvc waste pipe will slide neatly over 48mm tube to give a maintenance free finish.

 

[Letsgetitdone]

Silly question, but have you tried searching for "freestanding carports"?

Examples here...

Freestanding Carports - The Canopy Shop

Freestanding carports are a stylish way to cover your vehicle without having to worry about fixing to a supporting wall. Our free standing carports are the cost effective choice to keeping your car, van or motorbike sheltered from the weather all year round. Made from rust resistant aluminium...

thecanopyshop.co.uk

Even if you have, the images will give you an idea of the minimal amount of structure involved.

These look good, op if you are insisting on metal and DIY, why not use aluminium box section to build the whole structure? I get your probably more a function over form guy but do you really want to have to put up with scaffolders jokes for as long as you have it up? You can still clamp everything together or bolt them, I'm not sure about welding (look into it). I think box section because of the flat surfaces would be easier to work with than round poles as you would have ideal surfaces for glazing bars.

 

[Yerptie]

Unfortunately the vast majority of products on the market seem to either be lean-to (attached to a wall of the property, projecting from it) or a stand alone that doesn't extend beyond it's frame and leg supports.

To create the dry space without dripping rain water, I do need to extend the roof above and over the property gutter and one or two rows of roof tiles.

Scaffold related jokes, not a problem. I do enjoy a talking point!
The lady of the house has cleared the use of scaffold tubes. It is difficult to appreciate the aesthetic without it being in place, however, 48mm scaffold tubes are considerably less chunky than 8 or 10 x 2 timber rafters.

One problem I've now run into is the footings. I thought, rather hastily, that I'd have room for 12" square concrete poured footings to then add bolt down (with epoxy?) base fittings. That is going to move the upright poles/leg rows together quite a bit and make the gap rather narrow. I appreciate the use of cranked posts, as that would free up a good 12-13" of gutter + soffit depth. I'll have to check the width of the property foundations as it maybe possible to bolt the base socket to that - although I'd not really want to touch the foundations unless I have to, for risk of severely screwing things up.
This all said the concrete-in ground sockets would probably be OK in an 8"/20 cm block of concrete, so long as the block is reasonably deep, I'm thinking still 12"/30 cm deep.

I've looked into ground screws. I wonder if scaffold tubes can be attached to them securely. Perhaps this is not the best use for them, maybe it's OK as they are used for solar installations, which isn't too dissimilar to what I intend, albeit maybe a lot lower in height and at a steeper angle.

50 mm pipe wouldn't fit 48 mm scaffold tubes, inner dimension is too tight. However, 60 mm for use with pools etc. should. It's an interesting idea should it need covering for aesthetic reasons. The fittings would break the clean lines however, so there's that.

 

[Tigercubrider]

You can get powder coated tube for handrails or get tube coated.
There is also fibreglass scaff, unsure of the strength.

 

[Yerptie]

Thank you all for your contributions, even the sarcastic and amusing ones!

I am thinking that relying on scaffold connections entirely is not the way forwards. After all scaffolding has a temporary purpose and is meant to be disassembled and reassembled, thus being tightened afresh each time. A couple of Seasonal cycles and I think fittings may become loose.

~2 inch aluminium tubes for posts still seem like the least worst option. They are thinner than a 3" sq fence post. They don't rot like wood, and don't rust like steel may. Rather than looking for bolt-down options, I think concreting 2 ft of each post into the ground should be sufficient for up to about 8 feet in height.

Adding scaffold 'rails' to the tops of the posts, and spanning all the way down the length each side would be fine. On top of these two 'rails' the suitable clamps with holes in the wings could be used to crew on 2x6" rafters. Rafters attached with 2 screws for each clamp, at two points - this is typical of designs. Then add 2x3" noggins around the centre of each rafter, and maybe near either end too, to prevent rafter twist.
Glazing bars attach to top of each rafter.

I don't think there is really too much of an issue with snow loading, especially with a 10° slope. We simply don't get enough snow to worry about here, and the polycarbonate would sag more than anything - even a short 600-700mm width.
Not sure of wind effects, but I don't foresee them as a huge problem, again the glazing bars and poly would likely pop before anything else.

With 2ft sunk into concrete, I am not sure if there is that much risk of collapse from the posts falling over.

 

[Tigercubrider]

With fences, 25% of the post should be in the ground.
So 2 feet is a bit light but likely ok