Building off the back of an existing 30’ span building

[Full of bull(s)]

I’m beginning to look into building off the back of an existing 120x 30’ span portal frame with another 30’ span. Will anybody be prepared to take the job on as the existing posts are 7x4 roughly I think. 15’ bays with 7x3 timbers. Interior height isn’t an issue, 12’ to the eaves, I wondered whether a semi truss type design for the rafters with a horizontal brace would take some pressure off, I don’t want centre posts every bay but every other wouldn’t matter. Has anyone done this recently? Thanks

 

[Sharpy]

We have a 40ft span shed with 30ft span extension to one side and a 40ft to the other. No problem.

 

[Full of bull(s)]

It was more the post size. I had another 30’ span built a few years ago and mentioned about building off that in the future and it came with much heavier posts, the same as on a 45’ span I have

 

[B R C]

Interesting question, I guess anyone doing drawings to current spec will tell you, you need to replace posts with bigger ones, so cheaper to have a separate shed in that case….

 

[Mur Huwcun]

Just put a separate shed roughly 15 foot away from the gable end of your shed……

 

[Sutty27]

I’m beginning to look into building off the back of an existing 120x 30’ span portal frame with another 30’ span. Will anybody be prepared to take the job on as the existing posts are 7x4 roughly I think. 15’ bays with 7x3 timbers. Interior height isn’t an issue, 12’ to the eaves, I wondered whether a semi truss type design for the rafters with a horizontal brace would take some pressure off, I don’t want centre posts every bay but every other wouldn’t matter. Has anyone done this recently? Thanks

We’re abouts are you located?

 

[Full of bull(s)]

We’re abouts are you located?

Northallerton North Yorkshire

 

[FowlerandGilbert]

Good Morning @Full of bull(s)
Feel free to give us a call to discuss 01630 655 555 or email [email protected]
Have a nice day - Kelly

 

[Bucks Boy]

I’d build another stand alone shed. Avoid having a valley gutter. They always end up needing to be cleaned out.

 

[HatsOff]

I’m beginning to look into building off the back of an existing 120x 30’ span portal frame with another 30’ span. Will anybody be prepared to take the job on as the existing posts are 7x4 roughly I think. 15’ bays with 7x3 timbers. Interior height isn’t an issue, 12’ to the eaves, I wondered whether a semi truss type design for the rafters with a horizontal brace would take some pressure off, I don’t want centre posts every bay but every other wouldn’t matter. Has anyone done this recently? Thanks

I'd have thought it'd be OK or you could strengthen the current columns in situ.

The challenge with agricultural sheds is stopping them flopping over or blowing away, the vertical loads don't usually control the design.

If you wanted to take out the every other centre line of columns (which is what I think you mean by the bit in bold) then the design gets quite a bit trickier.

 

[Full of bull(s)]

I'd have thought it'd be OK or you could strengthen the current columns in situ.

The challenge with agricultural sheds is stopping them flopping over or blowing away, the vertical loads don't usually control the design.

If you wanted to take out the every other centre line of columns (which is what I think you mean by the bit in bold) then the design gets quite a bit trickier.

No sorry I meant I didn’t mind a centre post in the additional span every other bay as it is to be split into 30x30 pens so there will be panelling every other bay anyway. The existing shed is block walled right along the side I would be joining to so it won’t flop anywhere