Avoiding steel wind frame with portal I-joist frame

[thaldine]

I'm planning to have an internal span of 6.7m across a living space  in a 1.5 storey build with a ridge height of 6m and eaves of 2.9m with a profiled metal roof. Am I right in thinking this should be possible to achieve with the I-joist frame alone without a steel wind frame ?

Thanks in advance.

[JohnMo]

A sketch may help, to visualise more clearly.

[Russell griffiths]

You can do whatever you want, but it will always have a knock on somewhere. 
we wanted timber and no shell for a large span, but the timbers started to need to be 450 deep. 
without steel would your I joist start to come out at some ridiculous size like this. 
you might also need to decrease the spacing between them. 
all of the above adds to the cost. 
do you have a drawing. 
in the end we went with a steel mid span and it halved the size of the i joists. 
mine was just a roof, not a whole frame. 

[Conor]

Steel will likely end up being the easiest and most cost effective solution. That's why it's used so much. Do you have an SE that can looks tit for you?

[G and J]

My word that’s what got Gregg W in trouble lol

 

I keep reading steel is inexpensive but I’m damned if I can find sensible ways of guesstimating broad costs.

[saveasteading]

  On 02/12/2024 at 08:53, G and J said:

steel is inexpensive

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That beam is going to cost about £800 and require lifting gear and pads.

Maybe you can find a preused beam....just maybe.

You can use very deep joists at close centres with the added advantages of ease of fixing and easier service routes. But do you have the headroom? The cost may well be similar or worse.

It is very essy to find the joist size, but then it needs costing.

[thaldine]

I can't lay my hands on a fully alike depiction but somewhat like this with 350mm deep I joists at 400mm centres.

[Russell griffiths]

There’s two blokes on here who have done that configuration with I joists. @Gone Westand @Patrick

patrick isn’t on here much as he’s building up his empire. 

[JohnMo]

We have a steel frame at the front of the house buts mostly to hold the glazing, and a big roof overhang - original design was all wood, but was way to chunky. There is no other steel in the house. Our living room is just over 6m wide and about 6m tall. Big glulam beam, posi rafters at 600mm centres.

 

Part way through construction 

 

[Gone West]

  On 02/12/2024 at 16:18, thaldine said:

I can't lay my hands on a fully alike depiction but somewhat like this with 350mm deep I joists at 400mm centres.

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Yes, we built our house in a similar way but we didn't use a ridge beam. Our house was built in 2010 and was the second construction of that type that the TF company built. The first was an art gallery which was much larger than our house.

 

https://lowenergybuildings.org.uk/search.php?s=greendale

 

https://lowenergybuildings.org.uk/projectPDF.php?id=255

 

Edited December 2, 2024 by Gone West
Added link

[Iceverge]

Correct me if I'm wrong here. 

 

You have a vaulted living space that will be 6.7m wide so each rafter will span 3.35m and will be supported at the top by a ridge beam and 2.9m walls at the end. 

 

The ridge beam could be Gluelam, it depends how long it will be. 

 

The gable end wall will need to be strong Probably requiring a post to take the load to the foundation. I can't see why this couldn't be timber too. Depending on the amount of glass you plan to have. 

[thaldine]

thanks folks

[Gus Potter]

  On 02/12/2024 at 08:28, JohnMo said:

A sketch may help, to visualise more clearly.

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You can potentially save yourself a pile of cash if you post some sketches.

 

You seem to be at an early stage. Here we look at the overall design, areas of glazing and so on (this is for structural stability.. side ways wind loading for example) and try and look at the insulation strategy and how we do the SE work for this to make it buildable and economic.

 

  On 02/12/2024 at 07:43, thaldine said:

I'm planning to have an internal span of 6.7m across a living space  in a 1.5 storey build with a ridge height of 6m and eaves of 2.9m with a profiled metal roof. Am I right in thinking this should be possible to achieve with the I-joist frame alone without a steel wind frame ?

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The rafter spans you are talking about are modest.. no need for expensive I joists unless these can save you money on insulation... you may have a preference for what kind of insulation and roof covering you want? Sometimes we over engineer things so we make the buildability and insulation less costly for example.

 

The best advice I can give you on limited info is to try and figure out what stops your house moving sideways when the wind blows! If you have massive area of glass then these are sensitive to sideways movement and reduce the available walls that can resist the wind.

 

If I was teaching student Architects..(I do teach some and they in turn reciprocate) I would say.. bear building stability in mind and you'll have a good chance of actually getting your design built!