6.5m ceiling span

[al4x]

I'm currently looking for solutions on how to support a ceiling and also add additional roof bracing in a building with a 6.5m span. Currently it has a lightweight roof and is open to the eaves but has got supporting walls with a few roof trusses currently spanning the 6.5m we want to take out the stud walls to open it into a large kitchen diner. Obviously this span is too wide for conventional ceiling joists but would any of the engineered solutions for example wolf systems be able to do the job. Any advice or experience would be much appreciated.

 

[Softus]

You need to substitute any supporting walls with beams.

You need an architectural an engineer to calculate the beam type and dimensions.

You need to notify your LABC of this structural change.

 

[jeds]

Timber I beams will span that distance but they will probably work out at least 250 deep and maybe 300 - and they are v-expensive. Could you break the span with a steel beam?

If you are set on pursuing the timber option Email a plan with dimensions to one of the I beam distrubutors and they will usually work out a solution for you. I use Joseph Griggs in Gloucester and they are first class.

 

[al4x]

Basically i probably didn't describe it well enough but at the moment we have a lightweight roof that is decked with cut roof trusses spanning the 6.5m span These trusses are supported and its this room we want to open up and remove what we're guessing are supports for the trusses. The span the other way is about 8m with the trusses crossing where a beam would go. Its a bit of a quandry as presumably we would have no problem if we left the room open to the roof and put in bigger trusses which is something we could do but are trying to avoid, as is removing the entire roof and starting again.

 

[Softus]

Basically i probably didn't describe it well enough...

Er, I think you did.

...its this room we want to open up and remove what we're guessing are supports for the trusses.

Don't guess. Just consult.

The span the other way is about 8m with the trusses crossing where a beam would go.

In that case you can't put a beam in.

 

[al4x]

it does help to have background knowledge before you consult as so far we've used a few experts who have been utterly useless and have cost us a lot of time and money on this project so far.
Look at it another way if we removed the roof alltogether and put in roof trusses which may not be possible would you be able to cover a 6.5m clear span with trusses as this doesn't seem to be covered in the building regs documents I've seen.

 

[denso13]

Prefabricated roof trusses will easily cover that span.

 

[al4x]

ok getting somewhere now, how about ones made on site, basically the building we've got is far from square so the current roof is a bit of a work of art. Would we be able to put in enough trusses to have the same effect as using pre-fabricated trusses

 

[denso13]

For a 6.5m span your talking 294 x 72mm, 12" x 3", at 350mm centres

Prefabricated will be smaller timbers, therefore lighter.

Or as has already been said said a 300mm deep I-joist (maybe even 350mm)

 

[al4x]

mm that's a lot of timber. Does it make any difference if the roof covering is slates so relatively lightweight? and does the size of the purlins make any difference as presumably these are just supports to the purlinsand sorry to ask so many questions but are we be able to get pre-fab trusses for a non square building.

 

[denso13]

No the roof covering doesn't matter very much. You'll be using the space so the size of timber is to support the floor loads.

Ring a local truss manufacturer and ask the out of square question. I'd be very surprised if there wasn't some way round it. You see all shapes of roofs on buildings these days

 

[al4x]

We're not going to use the space, all it has to do is keep the roof up and provide a surface we can use to put a ceiling in basically it will be a bit like a big bungalow. There will be no watertanks or even access up there.

You see all shapes of roof but you don't see many like this, its the big asbestos bit! that extends past the old parts chimney.

 

[denso13]

Ah ok, don't know where i got that idea. Still need the timber as before to stop the ceiling sagging though.

Prefabricated would be my first choice. A standard truss for this span would be lightweight and much easier to handle.

A lot of work though to renew the roof so you can have a large ceiling

 

[al4x]

certainly is we need to change the roof covering obviously and have got a solution to slate using the existing structure just can't seem to find a sensible way to add the additional support needed. Looking at the building regs document for a decked roof we need supports about every 2.2m on the basis of our roof trusses and purlins. Could we run ceiling beams between the roof trusses? all seems a lot of agro to hold up a layer of plasterboard

 

[aconnor2]

you could put a larger beam running in the same direction and between the trusses splitting the span of the 8 m to two 4 m spans and then put some small beams or T section to break the 6.5 m span to two 3.25 m if its only taking ceiling load then it wont need too much steel and you'll get away with normal ceiling joists?
Thats if i have understood your question
also if there is no access into the loft area it will help to bring the loading down.