Building a covered work area with a 40' span, will this work?

[EddieWalker]

I plan to use these to attach the purlins if I use pipe. If I use square tube, I'd have to come up with a different plan, along the lines of what you described. These are made to attach the 2x4's to galvanized fence posts, which just so happen to also be 2 3/8" OD, which is why I like that pipe diameter so much. I also have bender dies and notcher saws for that diameter so I don't have to buy any tools to use it.

I understand your thinking, but wonder if you are pigeon holing yourself into a design using the wrong material because it's familiar to you and it's what you want to use instead of going with another material that would be better suited for what you are going to build?

I like the idea of those brackets, but when pricing out your materials, are they cost effective? Wouldn't cutting 2 inch piece of angle iron and welding it to the top of your truss be a lot cheaper?

 

[STx]

I totally agree with you about going DIY and saving $$ on materials. But a roof isn't something I'd fool around with unless I had a proven design.

One of the main advantages of a steel roof is having the trusses line up with posts on 8' or 10' centers. The purlins take the roof load and transfer it to the trusses. I think your design has the trusses too close together because you're using smaller diameter material. IMO, you'll end up using too much material and time, all for an unproven design.

You said angle iron is cheap, and you've found designs for it already - why not just use it? I'm not trying to get in your face about this, so I'm sorry if it sounds that way... I really respect you for building this yourself , so I'm just trying to help you choose the best option that combines strength with economy.

Have you checked out the garage journal forum? They also have a lot of knowledgeable members, and people post about new building designs all the time over there.

That's a fair question. Partially because I'm stubborn and don't want to use angle iron (it's not just cheap but it really isn't very strong) and partially (mainly) because those designs all include a horizontal brace right at the top of the posts that I really want to avoid.

 

[SirReal63]

So the pictures you posted were in construction progress and they added the extras after putting up the posts? Do you have any finished photos of the framing?

Never mind, I looked at the photos again and see that towards the back the spacing gets closer together. How did they cover the wider spacing in the front of the photo?

One last question, what's the measurement between the 2 pieces of square tube?

I have no idea what the gauge is.

Maybe these pics will help with your questions. Let me go measure the actual height of the truss/beam, I think it is 12" total.

The building is our Barndo that I am framing out, 40x70 with an 18' shop on the end where the roll up doors are. Our initial concern was the metal structure before the interior got framed in, as the interior framing will help support the metal building. Last Spring we had a few tornadoes in the immediate area and with the crazy wind it held perfectly fine. The roof structure is very solid, surprisingly so. I have stepped on the roofs of some metal buildings that left me with an uneasy feeling, this one does not.

 

[SPYDERLK]

I think your roof is going to be floppy. Take a look at a standard truss. Everyone focuses on the top shape, but the bottom chord all the way across the bottom is what holds the building together and keeps the walls from pushing outwards. I think you need to have a continuous chord from wall to wall and some stiffened legs to hold the top chord.

Fwiw, I'm a civil engineer by trade.

Yes. ... OP - To save on head space you could run that chord to the rafter joints on the 4.5' side braces. The chord is a tension member primarily but wind dynamics will cause some load fluctuations on the steady state. ... Perhaps every other chord could be cable.

 

[STx]

I understand your thinking, but wonder if you are pigeon holing yourself into a design using the wrong material because it's familiar to you and it's what you want to use instead of going with another material that would be better suited for what you are going to build?

I like the idea of those brackets, but when pricing out your materials, are they cost effective? Wouldn't cutting 2 inch piece of angle iron and welding it to the top of your truss be a lot cheaper?

I hear you and I'm trying to stay open minded. I don't mind using sq tube instead, I build with it a lot as well. It would speed construction because I don't have to notch everything but the die to bend it if needed is $500.

The brackets come to $250 total if I put the 2x4's 4' apart. Welding angle iron ears on would be cheaper, I'm not really sure which is better. They're probably equal.

Mainly, I'd prefer building with steel instead of wood because I can do it cheaper and faster. I don't really want to get into red steel beams if I can avoid it because I don't have the equipment to lift it into place, so that adds a lot of expense. Smaller structural steel that I can move around with what I have should be able to do this and I do want to do it right so I don't have to do it twice. I know that using bigger stuff is the proven method but, that method includes budgets I just don't have for material. I think using smaller material isn't common because the labor gets expensive, not because it can't be built strongly. I have the time to do the labor though, what I don't have is the money to go larger on the material and I need the structure to start earning again, so...

 

[STx]

I have no idea what the gauge is.

Maybe these pics will help with your questions. Let me go measure the actual height of the truss/beam, I think it is 12" total.

The building is our Barndo that I am framing out, 40x70 with an 18' shop on the end where the roll up doors are. Our initial concern was the metal structure before the interior got framed in, as the interior framing will help support the metal building. Last Spring we had a few tornadoes in the immediate area and with the crazy wind it held perfectly fine. The roof structure is very solid, surprisingly so. I have stepped on the roofs of some metal buildings that left me with an uneasy feeling, this one does not.

That is a great looking building, lots of open space overhead. It's interesting to see that they didn't use any purlins for the roof and yet you still have a very strong building that's already been wind tested.

 

[SirReal63]

They actually did use purlins to tie it together and to give a surface to attach the metal roof to, it doesn't show in those pics because the purlins are on top of the bubble wrap insulation. You can see it here on the right side, they ran these every 3'.

The height of the beams/truss is 12" and the uprights between the cords are spaced at 40".

It is getting hard to take pics now, the interior framing is at about 99%. It fills up fast once interior walls are up.

 

[STx]

They actually did use purlins to tie it together and to give a surface to attach the metal roof to, it doesn't show in those pics because the purlins are on top of the bubble wrap insulation. You can see it here on the right side, they ran these every 3'.

The height of the beams/truss is 12" and the uprights between the cords are spaced at 40".

It is getting hard to take pics now, the interior framing is at about 99%. It fills up fast once interior walls are up.

Thank you again for the photos, they are a huge help. If nothing else, they prove that I'm not entirely crazy.

 

[SirReal63]

I will PM you the link to my photobucket page where the rest of the pics are. I didn't use all of them on my build thread and maybe it will help. There are two buildings there, the 40x70 and the 24x24 guest house, they used a different technique for the guest house roof, but it was only spanning 24', I didn't like it but it too has held up through the same weather.

 

[farmer2009]

My chicken barns are 40' spans. They are steel trussed with angle iron web style trusses. They are a scissor style truss. 10 foot truss spacing with 2x6 purlins. There are U shaped pieces of about sheet metal welded to the trusses. The purlins are set edge ways in the U brackets and nailed in through drilled holes with 6 penny nails.