Vaulted ceiling

[BarnabyT]

I'm part way through a 2 storey extension. The first floor is gonna be a bedroom and dressing room/en suite. Its basically a 4 meter wide by 7 meter long rectangle room that I'm gonna divide up with stud work.

I'm considering a vaulted ceiling....I've not ordered any trusses yet.

How much more work is involved in having a vaulted ceiling? Will it need to have the roof redesigned by the architect with calcs, or can I just use scissor trusses rather than standard fink trusses?

 

[noseall]

How much more work is involved in having a vaulted ceiling? Will it need to have the roof redesigned by the architect with calcs, or can I just use scissor trusses rather than standard fink trusses?

Massive. Its like night and day. It's also exactly what we have just done on our current job. The net difference between the two designs on ours was about £6'000. That was without SE fees. There is the time consuming and costly ceiling/insulation detail to consider also.

You will need to get an SE on board and build it as a cut roof complete with birds-mouths over the support beams etc. We managed to salvage the steels from the previous ground floor extension as it was on the same footprint...

Vaulta3

• noseall
• 6 Feb 2022

Vaulta2

• noseall
• 6 Feb 2022

Vaulta1

• noseall
• 6 Feb 2022

He also requested a vaulted over the garage so that he could include a mezzanine in the tall copious space...

Crank5

• noseall
• 3 Dec 2021

Crank4

• noseall
• 3 Dec 2021

Crank2

• noseall
• 3 Dec 2021

Crank1

• noseall
• 3 Dec 2021

Crank1

• noseall
• 28 Nov 2021

You can see the finished article (vaulted bedroom extension) in the above image complete with lead sided dormer.

 

[Mr Chibs]

Nose all, Out of curiosity Why are some of the rafters doubled up... is this for velux to go in?

 

[BarnabyT]

Oh bloody'ell.... sack that then. It was only a possibility if I could have just used scissor trusses rather than fink trusses.

 

[Mr Chibs]

A mate of mine had scissors trusses for an extension he had, 5x4m installation went pretty smooth.

On a side note, I changed a flat roof to vaulted, after getting hacked off dealing with local roofers etc.

I built it myself, and it was fairly straight-forward. Never done anything like that before. Even installed velux.

Structural calcs were £150, installed a couple of beams and cut the birds mouths etc. Insulation wasn’t that difficult, this can all be done by a competent diy-er.

 

[Dereekoo]

I question to your BC perhaps, it looks pretty straight forward?

 

[Mr Chibs]

Thanks for that, even easier now.

That’s looks straight forward to me.
And my mates was done the same way, I helped him do it.

The faff was fitting the bracing for wind etc, as access for trusses are not as easy as beams and rafters.

 

[BarnabyT]

When I initially looked at it - being that its just a 3 sided box thats joining the existing gable wall - I thought surely i could just use scissor trusses instead of standard fink trusses - the idea being that the trusses are designed appropriately to be substitutes for standard finks. On that pic above, it appears that that is the case.

I will try and speak to the BCO and see what he says...... that build that Noseall has done is both complicated and impressive in equal measure, but mine is as simple an example as one could find.

 

[noseall]

Nose all, Out of curiosity Why are some of the rafters doubled up... is this for velux to go in?

Yes.

Believe it or not, they only arrived yesterday and I spent the morning taking them on site. We'll be fitting them on Monday and finally (sigh) ridding the site of the scaffold.

 

[noseall]

I will try and speak to the BCO and see what he says...... that build that Noseall has done is both complicated and impressive in equal measure, but mine is as simple an example as one could find.

The vaulted with the dormer over the bedroom was ok but tiling and weathering the bit where all the roofs converged (at the back left of the dormer) was an absolute fekkin nightmare. There was a huge concentration of work in a space where the rafter bottoms were virtually touching and where two valleys converged.

Conv1

• noseall
• 6 Feb 2022

Conv2

• noseall
• 6 Feb 2022

The garage was rather a challenge especially the steel (front and back). The rear 'covered area' roof steels land on a steel post. Because the building is cranked (another nightmare) locating the exact position and height of the post was very time consuming especially as they already had the post, so I had to work backwards.

 

[noseall]

Nose all, Out of curiosity Why are some of the rafters doubled up... is this for velux to go in?

Key

• noseall
• 12 Feb 2022

 

[BarnabyT]

Just thought I'd put an update on this. My builder and my mate who's a private building inspector (previously worked for Trafford Council) both said its fine for me to just use scissor trusses in place of fink trusses because the truss company have produced the calcs and they're happy. But the building inspector who's acting on behalf of my local council has said it needs a windpost..... ie the idea is dead in the water because the gable wall is already built. He said he'd spoken to the engineers at the local council and they've said that the maximum height from 1st floor to ceiling is 2.7m. Apparently they use a calculation that takes two thirds of the thickness of the wall and multiply it by 16 to give a max ceiling height. In my case thats 132mm (2/3 of the 200mm wall thickness - they don't include the cavity void) times by 16.... which is 2.1m. He said this is lower than a normal 2.4m ceiling, but the regs allow this to be pushed to 2.7 meters. He still thinks it would need a post.

 

[Mr Chibs]

What a bugger.

I don’t know much about wind posts, so can’t comment. Was having a read at this post, don’t know if it sparks any ideas

https://www.diynot.com/diy/threads/wind-post-is-there-another-method.507399/

If scissor/wind posts won’t work, what about having a raised collar style roof, perhaps you could leave the ceiling chords/binders open.
Will still feel lofty.

Thanks for the update.

 

[BarnabyT]

So..... I've been looking into this a bit further and was wondering if anyone could assist my understanding of the following diagram..... which is from approved document A and I believe is what the building inspector is referring to.....

At part A it details the requirements for extra restraint. It says that if h is greater than 16 x t, then restraint has to be added where the dots are. Now.... t = sum of thickness of leaves plus 10mm.... ie 210mm. So 16 times 210mm is 3360mm. So I'm wondering why I cant do what I want to do, provided the height below the highest point of the ceiling line is 3.36m.

And.... X is the height from the ceiling joists to the apex. And h is half X. So the above should only apply if I want to vault the ceiling above the halfway point of X. So if I only vault it to half of x, then surely that would be fine too. Either I'm missing something here (very likely) or the building inspector has got it wrong.

But..... there is another diagram (Diagram 6) that shows maximum storey heights....

I'm confused about point D and C in the above diagram.

 

[Mr Chibs]

I’ll have a read as I’m interested in this.

Also FWIW with scissor trusses, the Ridge/high point in the room is lower than the actually ridge by possibly 700 mm, which height is the BI working with?