Timber frame roof

[pauldoc]

Not sure if this is a silly question but here goes. What is the usual way a roof comes with a timber frame kit. 

By that I mean are the rafters already assembled in an  'A' frame, attic frame type assembly like a big triangle etc and the notches cut to sit on the wall plate,  or are they loose and have to be cut and assembled on site? 

Hope that makes sense

[IanR]

My Touchwood roof (I-Joists) came in 12m blanks.

 

But, I have a large number of the same length of joist with the same cut at each end so was more economical to cut on site.

[pauldoc]

Did you have to work this out on site or did the frame company give you the cutting schedule? 

I am asking as it looks like I missed this on the original order. I was expecting the roof to come pre cut and frames so to speak. But it has turned up as loose timbers. Obviously this has not been accounted for in the budget! 

[IanR]

Those nice chaps from Touchwood built my frame, so this was all part of a package. They had a cutting list from their frame designer to work to.

[pauldoc]

ok so at the very worst there should be a cutting instruction list provided somewhere with everything that's been delivered do you think? Doe this list show the angles etc do you know? My main contractor is putting the frame up, not the frame company

 

[pauldoc]

1 minute ago, Sensus said:

It depends... some companies (and/or designs) favour 'trussed rafters' or 'attic trusses' (where they come assembled as a full triangulated truss), others favour 'traditional cut roofs' (with separate purlins and rafters), yet others panelised 'cassette' systems.

 

The company I used to be a Director of tended to favour cut roofs, for a variety of reasons (amongst which easier transport and erection on tight sites, along with it being more favourable to their own manufacturing facilities), but others differ.

 

Any competent company will discuss this sort of stuff with you before you place the order, though.

I would have thought that to be the case too! Unfortunately this area seems to have been missed, and assumptions made.

When you say 'cut roofs; I'm guessing that means the joists and rafters are already cut with the required angles etc and then the frame/triangular shape is assembled on site?

[pauldoc]

the builder is putting in a call. I think you are right and the details should have been explained before. Unfortunately assumptions were made and this was missed.

Speaking to the builder today it looks like just the raw materials have been sent. Awaiting the 'additional cost' this is going to be!

[IanR]

I was shocked how quickly Touchwood got through cutting everything to size. I would have thought there was a cutting list somewhere, They've had to work out how much timber you need so must know each piece that is required.

[pauldoc]

Just had a quick chat with my builder who has spoken to the frame company.

The feedback is that the frame company has just provided loose timbers to be cut on site to construct the roof.. And it seems there are no cutting or assembly instructions.

There is a roof plan in all the drawings, I guess they work from this

These have to be worked out on site but 'others'  Maybe as a first time self builder I have been somewhat naïve.

I guess if I had used the frame company for the erection of the build this would not have come up

[IanR]

Might be worth asking the frame company the cost of producing a cutting list. If all the timbers are shown on the roof plans, and assuming they are CAD drawings, then they likely have a quick process to produce the cutting list. They'll also be working from 1:1 data which will be far more accurate than your builder having to scale off a drawing.

[pauldoc]

44 minutes ago, IanR said:

Might be worth asking the frame company the cost of producing a cutting list. If all the timbers are shown on the roof plans, and assuming they are CAD drawings, then they likely have a quick process to produce the cutting list. They'll also be working from 1:1 data which will be far more accurate than your builder having to scale off a drawing.

thanks that makes sense, I will do that.

I really thought that this would have been provided, especially if the frame company had been used to erect?

[Stones]

Of the 6 houses we have built, the current one is the only one that has used rafters in certain areas (engineered trusses elsewhere).  These came as uncut lengths to be finished on site. With our wall plate and ridge beam both fitted and leveled off by a site laser, the joiners were able to cut all rafters to the same length, I suspect saving a great deal of time. 

 

Our previous builds have all been engineered trusses, this being the standard offering of by most (if not all) Scottish TF suppliers.

[IanR]

4 hours ago, Sensus said:

 

Part of the problem is that it will be far more accurate than the TF your builder has assembled, too.

 

A cutting list would be nothing more than a rough guide: they're going to have to site check each measurement, anyway, otherwise you're asking for trouble.

 

You do NOT want them to pre-cut each timber on site, to a drawing/cutting list, without the accuracy of CNC cutting equipment and without them being able to take check measurements against the actual frame in-situ. If you try to do so, it WILL go wrong and lead to extra work and costs - I guarantee it.

 

I must admit, since the OP only questions the roof, I'd assumed the rest of the TF Kit was either pre-cut stick build or panelised. Either way, perfectly OK to cut roof to a cutting schedule.

 

Touchwood cut the vast majority of my entire frame on site and to the cutting list. Joe that does the cutting works about a week ahead of the erection team, so nothing built to measure to anyway. And their process certainly works, anything I've needed to measure so far has been within millimeters of where it should have been.