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Roof type and calculation required for building control

Hello

1. Is it cheaper to get a pre-made truss roof or have a roof constructed on site?
2. Do building control require the truss structural calculations to be submitted with the plans for a full building control application, or is it ok just to say the roof is to be created by a truss manufacturer?
3. Does anyone know any truss manufacturers that will provide the structural calculations free of charge?

Thanks

3 Answers from MyBuilder Architectural Designers

Best Answer

1. Is it cheaper to get a pre-made truss roof or have a roof constructed on site?

Probably not a lot in it but may depend on where you are building and local labour costs.

Materials will be less labour will be more for construction on site.

Time savings from a trussed roof will save money if project is financed from a loan.

I like the ease and speed of trusses.

2. Do building control require the truss structural calculations to be submitted with the plans for a full building control application, or is it ok just to say the roof is to be created by a truss manufacturer?

Building control will need to see the calculations before the trusses are installed. You will be able to get conditional building control approval to allow you to start.

3. Does anyone know any truss manufacturers that will provide the structural calculations free of charge?
All truss manufacturers should provide this.
I have used Trussform a few times and they are good if you are in the right area.

2019-11-25T14:40:02+00:00

Answered 25th Nov 2019

A couple of additional points on what you have asked:-
Cost implication of timber aspects of Truss roof v cut and pitch (on site) roof. You need to consider (a) how you lift into position, if you require crane, you need to consider how close you can get to site and whether there are any overhead cables that may need to be temporarily removed and re-fixed or at least have extra insulation added. (b) How you intend to store on site (what room is available) trusses must be stored and secured in a vertical position, storing horizontally particularly on uneven ground can substantially weaken the truss joint plates. Therefore storage is easier with cut and pitch roof.
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Building control will require calculation for both a cut and pitch roof and for a truss roof - TRADA does span tables that may assist for a cut and pitch roof, but it is better to check from first principles, in which case a structural engineer is required. As the previous reply noted building control will allow you to start a build without those calculations as long as they are ready by the time you are pitching the roof. There are many truss companies and dependant on area you need to get prices from your local one as haulage costs are considerable over distance - Builders merchants can also supply these. Once you have a quote for the truss supply based on the information you have given and you have accepted it and paid for them the truss company will give you the confirmation calculations that you can forward to building control.
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Several things to think about which again depend to some degree on how complicated your roof is. If your roof has lots quirks eg dormer roofs and varying sized hip ends it is sometimes just as quick to cut and pitch. You also have an advantage with cut and pitch if your bricklayers haven't got the walls parallel or particularly level, or in fact if there is an intentional step in plate heights. I.e. cut and pitch is more flexible where-as trusses once ordered come as your order and if you've slipped up on measurements or loadings you are not going to be able to change them. Sending back and getting standard timber sections is relatively easy.

2019-11-27T16:25:01+00:00

Answered 27th Nov 2019

I prefer a roof built on site using rafters and purlins, simply because it usually provides maximum loft storage space which is nil or very limited with roof trusses.

2019-12-06T17:50:02+00:00

Answered 6th Dec 2019

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