Advice on Shed build please

mobfromcork · 10-06-2020 8:38pm #1

Folks,

I have to build a 24ft x 24ft x 10ft storage shed up the back over the next while and am looking for some advice on the design of the roof please. I need to do a big job on the house later in the year that will need a full clear out of a lot of rooms so need somewhere to store furniture and also all my tools, mowers, bikes etc that are currently in a garage that is part of the house. It's somewhat smaller than most farm sheds for sure but hoping someone might have done something similar, albeit on a larger scale.

Thinking of using all 40x40mm 4mm box steel and welding up a basic frame. All walls to be 8 foot high. A-frame roof rising to 12 feet at apex. Weld 4 roof trusses with plates so they can be attached to the walls underneath 8 feet apart.

I'm going to clad the whole lot in box profile sheets, non-drip for the roof. We are a bit stuck with what to do with the roof.

Thinking of welding trusses together like the ones below - 4 trusses over the 24ft length. #

Make them up as 8 triangles on the ground and bolt and then weld them together when they're up. What would be the easiest/best way to run and attach the purloins (either timber or metal)? I've done shed roofs before but always using timber either 3x2s or 4x2s and 2x2 purloins going horizontally to attach the cladding to.

Anyone who has done this before have any advice to offer please?

Thanks
Mark

cjpm · 10-06-2020 9:41pm

Your middle truss design is very obviously structually unstable and will sag big time, whilst blowing apart the supports it sits on.

mobfromcork · 10-06-2020 9:58pm

cjpm wrote: »

Your middle truss design is very obviously structually unstable and will sag big time, whilst blowing apart the supports it sits on.

Sorry, well spotted - I jotted it down from this pic here
https://www.pinterest.co.uk/pin/314970567662954402/ but have the triangular bit the wrong way around.

I saw from other steel sheds I was looking at online they just had vertical supports (just like I had planned for the front and back wall) but had left some of the internal truss supports higher to give more height in the middle of the shed. I can come down to the same height as the top of the wall if needed though.
I couldn't find info online regarding spans for the steel and whether the 40x40x 4mm would be strong enough.
Do you think the weight of the sheeting will be enough the push the walls out even running the steel/timber purloins all along the trusses?

Wildsurfer · 10-06-2020 10:39pm

Why not just do a portal frame with RSJs. You'd have it together alot quicker than your original plan

Nekarsulm · 11-06-2020 7:37am

If your shed is going to be 24 foot long, and you are going to use box profile on the roof, I don't see the need for 5 steel trusses.
3 would do.
24 foot is an awkward lenght, could you not make it 30 foot long, and save cutting the timbers?
They come in 15 or 16 foot lengths.

mobfromcork · 11-06-2020 9:31am

I haven't priced up RSJs yet. I'll give a ring around to a few places today. I'm trying to keep the cost down as we need the money for the job on the house.
Nekarsulm, we went for 24ft as when we priced the steel it came in 7.5m lengths or 24ft 6inches so was planning on using that and cutting wood (if we are using it) at 16ft and 8ft lengths. I also have a corner of the field that's it'll slot in nicely to next to a wood drying shed that's there already.

amacca · 11-06-2020 10:11am

mobfromcork wrote: »

I haven't priced up RSJs yet. I'll give a ring around to a few places today. I'm trying to keep the cost down as we need the money for the job on the house.
Nekarsulm, we went for 24ft as when we priced the steel it came in 7.5m lengths or 24ft 6inches so was planning on using that and cutting wood (if we are using it) at 16ft and 8ft lengths. I also have a corner of the field that's it'll slot in nicely to next to a wood drying shed that's there already.

I'd be interested in hearing about your progress. Looking around at kit sheds and pricing lads to supply kit and erect and finding it expensive to say the least, considering buying the materials and doing the work myself tbh

mobfromcork · 24-08-2020 10:08pm

Just a quick update, ended up designing a shed 7.5 metres x6 metres with an A frame roof.
Levelled ground, lorryload of 804 levelled, going to pour a 4 inch concrete base - form is made and levelled, damp proof membrane down, steel mesh in position, nearly ready for concrete (weather permitting in the next few days)
Steel being ordered tomorrow followed by cladding.
Going for 40x40x4mm for the walls and trusses and 30x30x2.5mm for the purlins.
Will post up a few pics as we go. Getting help from father in law with the welding. https://photos.app.goo.gl/31LnPh3tdD22EMSU9

jimini0 · 24-08-2020 10:27pm

mobfromcork wrote: »

Just a quick update, ended up designing a shed 7.5 metres x6 metres with an A frame roof.
Levelled ground, lorryload of 804 levelled, going to pour a 4 inch concrete base - form is made and levelled, damp proof membrane down, steel mesh in position, nearly ready for concrete (weather permitting in the next few days)
Steel being ordered tomorrow followed by cladding.
Going for 40x40x4mm for the walls and trusses and 30x30x2.5mm for the purlins.
Will post up a few pics as we go. Getting help from father in law with the welding. https://photos.app.goo.gl/31LnPh3tdD22EMSU9

Not meaning to pick faults but you will need bricks under the mesh to keep it up off the ground.

mobfromcork · 24-08-2020 10:36pm

jimini0 wrote: »

Not meaning to pick faults but you will need bricks under the mesh to keep it up off the ground.

You're dead right, well spotted. I'll be popping in 1 inch slips underneath them before we pour. Got a bit dark to do it this evening and I still have to tie them together with wire as well. Going to drive a few more vertical pieces of rebar down deep into the earth as well and tie them to the mesh also.

Water John · 24-08-2020 10:41pm

If you can also get the pegs holding the timbers down level or shy of the timbers it would be a great help when screeding.

mobfromcork · 24-08-2020 10:50pm

Fair point, I pounded most of them below the level with a sledgehammer but need to cut the tops of the others with the saw.

kieran. · 24-08-2020 11:10pm

mobfromcork wrote: »

You're dead right, well spotted. I'll be popping in 1 inch slips underneath them before we pour. Got a bit dark to do it this evening and I still have to tie them together with wire as well. Going to drive a few more vertical pieces of rebar down deep into the earth as well and tie them to the mesh also.

Your lap on the mesh is light it should be 400mm approx (2 squares) I'm assuming it's A393. If you have rebar use it to form the laps if you haven't enough mesh.
Don't drive rebar deep into the ground because it will puncture your DPM and also the rebar will rust eventually weakening your slab.
If you are going for 40 box be careful where the fixings into the concrete are if you go through the centre of the bottom rail with a M10 anchor you will only have 15mm of an edge distance I'd be inclined to go for a 75mm angle or similar.

mobfromcork · 24-08-2020 11:37pm

Thanks for the advice. That's a good point about the DPM. I tore a bit by accident this evening with the sledge so might need to patch up tomorrow. I have some mesh left alright but as I'm only pouring approx 4 inch of concrete I didn't want the mesh to sit up too high. In fact initially we had a 2 squares or more in some places of an overlap but it was pushing the mesh up too far so I cut it back a bit. May have been a rash move. Also, this shed won't be holding anything of huge weight really. Main workshop will still be in the other garage. This is for bikes, tractor lawnmower, garden tools and some storage but there will be no heavy machinery etc as such so that's why we opted to only pour 4 inches.
We were planning on welding some pre-drilled 5mm flat bar or 40x5mm angle iron to the inside wall of the bottom rail in a 5 or 6 places on each side so it was sitting on top of the concrete but the anchor bolt or fixing would be away from the edge by 60mm or so. It's a bit more work alright but less chance of the concrete cracking at the edge.

jimini0 · 25-08-2020 10:34am

mobfromcork wrote: »

Thanks for the advice. That's a good point about the DPM. I tore a bit by accident this evening with the sledge so might need to patch up tomorrow. I have some mesh left alright but as I'm only pouring approx 4 inch of concrete I didn't want the mesh to sit up too high. In fact initially we had a 2 squares or more in some places of an overlap but it was pushing the mesh up too far so I cut it back a bit. May have been a rash move. Also, this shed won't be holding anything of huge weight really. Main workshop will still be in the other garage. This is for bikes, tractor lawnmower, garden tools and some storage but there will be no heavy machinery etc as such so that's why we opted to only pour 4 inches.
We were planning on welding some pre-drilled 5mm flat bar or 40x5mm angle iron to the inside wall of the bottom rail in a 5 or 6 places on each side so it was sitting on top of the concrete but the anchor bolt or fixing would be away from the edge by 60mm or so. It's a bit more work alright but less chance of the concrete cracking at the edge.

I wonder could you add a 2x2 on top and put 6 inches of concrete. 4 inches is very light. It would only be another 2 m3 of concrete

mobfromcork · 08-09-2020 8:56pm

So we poured the foundation last week, got 5 cubic metres of concrete and after a few hiccups at the start getting the lorraí in we got it poured. Steel truck arrived at the same time as the concrete so it was a busy few hours. Father in law arrived on Friday and we started the cutting and welding. He's an enthusiastic beginner/amateur so it's a learning curve for us both. I had a design drawn up with a few changes from the one above. Joe did the welding and I did the cutting, grinding and general donkey work. We made the two gables first, then the four trusses and we have the back wall tacked. Going to finish that tomorrow and do the front wall and doors
https://photos.app.goo.gl/TBAyiSK6V2119pBJ9

Have to attach flat bar to the underside of the trusses so we can bolt and then weld them to the bar at the top of the walls.
Doing the purlins in 30x30x2.5mm box and going to weld 30x30mm angle into the trusses to sit the purlins into.
Going ok so far, think it was overkill for what we need it for but would rather overdo it than underdo it.

https://photos.app.goo.gl/4EsDzfAgbMoitxxi6

Will give it all 2 coats of primer when done. For anyone who said they were interested in doing it DIY so far the main costs are
Steel - 987 euro
Concrete - 420
Timber for base and rebar - 250ish (I think)
804 stone - 250
Primer - 50
Cladding and gutters and hardware etc Quotes from 1650 - 2600 depending on supplier and spec.
So around 4k in total I reckon by the time we're done.

We had general costs like cutting and grinding discs, welding rods etc as well. We are using a decent inverter welder and Joe has a 355mm steel mitre saw which makes the cutting fairly quick and accurate. We had to make some of the long angles truss cuts with a grinder which took longer to cut and weld due to the inaccurate cuts.

Will post a few pics when we're done.

monseiur · 09-09-2020 3:49pm

Nice job man. Well done
I enjoy following DIY jobs with photos as the work progresses.
Consider welding cleats on trusses to carry purlins, also non drip cladding or if the budget allows insulated cladding.

M.

countryjimbo · 11-09-2020 11:58am

Shaping up nicely, do keep us updated with plenty of photos.

mobfromcork · 14-09-2020 9:45pm

Wasn't around for a few days but we got the frame up today. We welded cleats on the trusses as advised above using 30mm angle iron.
https://photos.app.goo.gl/N3VVrTr2etGpgnwEA

We also welded tabs 16cm long using 40mm X 5mm steel bar at the bottom of each upright and drilled 12mm holes using a cobalt bit in them. When we stood up each wall we drilled down through these holes with a 10mm concrete bit and used the screw down concrete fixings rather than expanding anchor bolts.
We also had horizontal tabs welded and pre-drilled with 4mm holes. We were going to use tec-screws to temporarily secure the walls together but they kept snapping so we ended up just clamping and welding the walls together instead.
https://photos.app.goo.gl/7vJ1Vhoy82PAgHHG9

We took a good bit of time making sure all the cuts and plans were accurate and it really paid off when we put it together. Everything lined up really well and is square and solid. Any issues were due to poor screeding/floating the concrete in two areas but it's not too bad either.

https://photos.app.goo.gl/W9hHCm3SKRkBrk2w6

We are going to weld plates at the ends of the trusses and put them up on the walls tomorrow. Then put on the purlins and finish putting primer on the whole frame. Back to work for the rest of the week but might get the door made up in the evenings.

mobfromcork · 16-09-2020 9:56pm

https://imgur.com/gallery/hsXOcNA

Steel shed frame https://imgur.com/gallery/JAWzvKo
[IMG]http://Steel shed frame[/img]https://imgur.com/gallery/JAWzvKo
Trusses and Purlins up

mobfromcork · 09-10-2020 11:41pm

We worked on it last weekend and for a lot done. All the cladding apart from the door is finished. One door is welded up and hanging. Doing other one in the morning. Must put up ridge flashing and sort out the rainwater gutters. I want to fill an IBC tank and let the rest off down into the stream behind the shed. Give the internal steel one more coat of Löwe Paint and then paint the floor with something to help clean easily rather than the raw concrete.

https://photos.app.goo.gl/3PRV4oCo5Suiwrwp7

Will tidy up around it as well, maybe more stone to bring it all up a certain level. Run electric cable up them. We were haunted with the weather for the most part and I got to learn how to do some basic welding so happy with that.
If anyone is going DIY I'd be happy to answer any questions that came up.l

Track9 · 29-11-2021 10:14pm

Wonder can some one give me benefit of their experience.Half way thru building 40 x30 Dry Shed.Contractor made mistake & legs are circa 4 ft too long,putting the Spex in very exposed situation ( no shelter from hay shed )

Contractor gone missing on other jobs.indeed he made inaccurate claims to get work,eg has team of men.Not so ,no one else.So the steel us standing,but no ealks or roof.Have tried everything, incl.hoing legal.

Please any suggestions helpful,as I'm at my wits end.

Tileman · 29-11-2021 10:21pm

Unfortunately that’s nearly the same with all she’s builders. They have several jobs on the go. 4ft is. A serious difference. And it is obviously not what u ordered.

hiw much % of the cost have you paid over. So u have any written quote or agreed payment terms etc.

im just finished a big job and it started on April. They should be coming to a quite time now as most ag sheds are finished.

has he given u any indications of time

Advice on Shed build please

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