Modification of Quanset barn

Hi guys, I need some help modifing my proposed man cave, i have bought an old Quanset barn that i wish it put up at my new farm home, the existing barn is about 8.1 metres wide and after 3 weeks work is now in a hundred pieces, i want to extend the roof out another 4m wider to make the building about 12m wide, unfortunately i am no structual engineer so i have come up with a solution that i think would work, can anyone make any sugestions if i am going about this the right way. sorry about the cad but ms paint is all i have
Any help much appreciated


Dont like your chances if local body engineers/inspectors get picky... how long is each 'bay', 3.6 meters or a bit more?...if you used 4.5m sticks instead of those you have there you could get it about 1m longer per bay , or is that not practicle on your block of land.
hi Jaymac, I have looked at extending the wood for each bay they are currently 2.900 and it is an option, but the cost of all the wood is more than the steel required to just make a another hoop, and just add 6 more pieces of wood.
i can just fit in another hoop length wise on the land i have, but i really need it to be wider if possiable or with all the toys it's going to be crowded in there lol, yep the powers that be might get touchy if the mod looks agricultual thats why i hoped an engineer person might have an idea,the barn did have a mezanine floor that was about 3m deep and ran all the way across ie 8 x 3 but the borer got to it before i did and it was a throw away, and will probably cost a small fortune to replace so i figured if i could go wider it would be good, i found these pics of another barn that was for sale a few weeks ago and it looks like it started life about the same size as mine but it not only was made wider but a lot taller, and i really don't need that much height, unless i was going to build a Saturn five in there, now thats an idea????


These Quonset huts were developed as a quick and cheap erection during WW2, not that this helps you with your question. But the strength is in the shape (ie. cross section shape) so you can't just spread it or raise it, it has to follow the curve I believe.
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Jim Craik

Lifetime Supporter
My family lived in Quonset huts for six years, three years on Canton Island and three years on Wake Island.

Now Quonset "huts" are quite a bit smaller than the Quonset "barn" that Graeme is talking about, but............

I was fairly young then, but we have photos of our "hut" on Wake, they cut a big section on one side and rolled it up and out, added a couple of 4x4s, some screens and you have a family room addition.
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These Quonset huts were developed as a quick and cheap erection during WW2, not that this helps you with your question. But the strength is in the shape (ie. cross section shape) so you can't just spread it or raise it, it has to follow the curve I believe.
Dalton is right. These structures are designed around the principal of the arch and the diaphragm. They are quite strong as long as the structural loads are transferred to the ground through the diaphragm and arch, without generating bending stresses. You cannot just "cut & paste" these systems into another geometry without careful engineering analysis. You may not have roof loads like snow to deal with, but wind loading can be just as devastating. Your scheme is also asking the arched truss components to do things they were not designed to do. I'm an architect and I would not modify this thing in any way without bringing in a structural engineer to run an analysis. Be very careful.
This type of construction was greatly used in WWII

These are pics of a Blister Hanger. This one is a "Double Over Extra"..The largest ones they built...I dont have any pics of the smaller ones, but they are exactly the same shape....just narrower and lower

This hanger was used by the USAF 368th Fighter Group, and would have had P47 Thunderbolts in it

family pics before 2008 626.jpg family pics before 2008 627.jpg

It is still in use today, but sadly not by Thunderbolts...
Thanks Dayrl, for the advice, shame i could not have bought one the size that mickky3 posted that would almost fit all the toys, these barns are not available very often over here, so i had to take what i could get, the barn did have a semi free standing mezanine floor that i could rebuild, i am now looking at making another hoop to add another 3m to the end of what i have,the current building is about 9m long and if i put 2 cars behind each other it does not leave a lot of room for a workbench at the rear end, but finding the curved iron will be a problem it takes about 20 sheets to cover a 3m module, i have seen several of these locally with clear panels in the roof and sides mine has about 60 sheets total, so to add another module i need to replace 20 sheets with clear panels, that seems two many to remove i figure the iron also helps spread the loading, and i wonder about the strength of the clear sheet, do you have any thoughts on that, its just the original barn had none, and as i dismantled it i first removed the entire top run of iron some 11 sheets. It was like having the sun inside the building compared to the dark mancave that it was, it did not seem to bother the structual side of things as i walked about up top it did not wobble like a jelly do you have any recommendations. The other thought was to add another 1.5m under the sides that would make it 6.5m in height and perhaps allow 1 level for car strorage and another above it above that for storage, the thought was if i installed a 4 post lift i could wheel cars off the lift onto the mezanine level for starage, with other stuff above that.
Hey Graeme. Have you moved house?? Let me know your address and phone number and I'll pop in for a cuppa and tour of your mancave.

You know Ive moved house? - to a lot bigger place as I ran out of space when you last saw me.
Oh - and Ive collected a few more cars and bikes since then - you know what its like, have space - will fill.

Hi Bruce, Long time no see, need to catch up have you still got the same cell if so i will call tomorrow, got in so much trouble last time i came to your mancave, but thats another story, lets just say i'm a free man now lol. And now just down the road in Maungaturoto. You have a pm

Best Regards
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Well bugger me!! I was down that road only 2 weeks ago at the college there - looking at doing some more work for them. I could well have popped in for a cuppa. Are you on the metal part of the road? I only ask that as to what car I should drive down.

As you're only around 45 minutes from my new place I best make like a good neighbour and come down this Christmas holidays and check on progress.