Wide, Low Pitch, Vaulted Roof - Options ?
Discussion
When I built my 8m x 8m kitchen I was advised to use a steel frame to obtain the above.
I'm now considering a similar build but for a 8m wide x 12m deep garage with an eye to possibly converting it to a bungalow in many years time
As I'm thinking of having brick or block walls is a steel frame still the answer ?
It occured to me that a steel ring beam would do the same job - stopping the walls spreading - albeit I'm not a structural engineer, or are there better options ?
It was a pain to dig a larger foundation for the columns, bolt them down, bolt the blockwork to them and I have the haunches in the room, I have no idea of the loads and I'm guessing the beam would have to be substantial or require a central tie to be cost effective.
I will of course be using an SE when the time comes I just find that they only do what you ask and rarely make suggestions themselves.
I'm now considering a similar build but for a 8m wide x 12m deep garage with an eye to possibly converting it to a bungalow in many years time
As I'm thinking of having brick or block walls is a steel frame still the answer ?
It occured to me that a steel ring beam would do the same job - stopping the walls spreading - albeit I'm not a structural engineer, or are there better options ?
It was a pain to dig a larger foundation for the columns, bolt them down, bolt the blockwork to them and I have the haunches in the room, I have no idea of the loads and I'm guessing the beam would have to be substantial or require a central tie to be cost effective.
I will of course be using an SE when the time comes I just find that they only do what you ask and rarely make suggestions themselves.
We've just built a large extension, part of which is a large family kitchen/diner with a vaulted ceiling. Ours is around 7m x 12m.
We used timber trusses like this:
https://imgur.com/a/zOD5c21
They're big buggers, 9" x 2" with several doubles either side of the velux windows and a couple of triples. Our ceiling height is approximately 3350mm.
Edit - sorry, just realised you wanted low pitch so this may not be of help!
We used timber trusses like this:
https://imgur.com/a/zOD5c21
They're big buggers, 9" x 2" with several doubles either side of the velux windows and a couple of triples. Our ceiling height is approximately 3350mm.
Edit - sorry, just realised you wanted low pitch so this may not be of help!
Edited by Rosscow on Monday 12th November 12:06
V8RX7 said:
...I just find that they only do what you ask and rarely make suggestions themselves.
Sounds like time to find yourself a better Structural Engineer...Is there any opportunity for a ridge beam?
With a ridge beam, the eaves thrust is not much of an issue. Without a ridge beam, its a question of whether you provided all the rigidity at the ridge connection, or whether you use portal frames or an eaves ring beam that give some rigidity at the eaves connection, too. Of the latter two, I think that portal frames are structurally more efficient - you certainly don't often come across the ring beam solution.
Do you need a completely 'clean' vaulted ceiling, or would you be prepared to accept intermediate trusses, or maybe steel tie bars on turnbuckles.
For what it's worth, I've just got the engineering back on a not dissimilar structure (8.5m span x 15m long main space, 17 degree roof pitch) and we ended up with purlins and two intermediate trusses as per following design:
V8RX7 said:
Rosscow - thanks but yes - keeping under PD height means circa 10 degrees
By the time you go that low, you may as well just design it as a flat roof....never ceases to amaze me, the complications and compromises that people will pursue in order to avoid a simple Planning application, though.
Equus said:
Sounds like time to find yourself a better Structural Engineer...
Is there any opportunity for a ridge beam?
With a ridge beam, the eaves thrust is not much of an issue. Without a ridge beam, its a question of whether you provided all the rigidity at the ridge connection, or whether you use portal frames or an eaves ring beam that give some rigidity at the eaves connection, too. Of the latter two, I think that portal frames are structurally more efficient - you certainly don't often come across the ring beam solution.
Do you need a completely 'clean' vaulted ceiling, or would you be prepared to accept intermediate trusses, or maybe steel tie bars on turnbuckles.
For what it's worth, I've just got the engineering back on a not dissimilar structure (8.5m span x 15m long main space, 17 degree roof pitch) and we ended up with purlins and two intermediate trusses as per following design:
Yes - I've got to find a new one, I've had two good ones both since retired and I've since used two more who I wouldn't use again.Is there any opportunity for a ridge beam?
With a ridge beam, the eaves thrust is not much of an issue. Without a ridge beam, its a question of whether you provided all the rigidity at the ridge connection, or whether you use portal frames or an eaves ring beam that give some rigidity at the eaves connection, too. Of the latter two, I think that portal frames are structurally more efficient - you certainly don't often come across the ring beam solution.
Do you need a completely 'clean' vaulted ceiling, or would you be prepared to accept intermediate trusses, or maybe steel tie bars on turnbuckles.
For what it's worth, I've just got the engineering back on a not dissimilar structure (8.5m span x 15m long main space, 17 degree roof pitch) and we ended up with purlins and two intermediate trusses as per following design:
The problem with future conversion means I's like to keep my options open - ie the best feature of my house is the wall of glass and if I retire to this in the future I'd like it again which precludes a ridge beam.
I don't object to tie bars but that's as far as I'd go
I can see a ring beam using more steel but if i saves the hassle of the frame legs / foundations I'd pay a reasonable amount more
Equus said:
By the time you go that low, you may as well just design it as a flat roof.
...never ceases to amaze me, the complications and compromises that people will pursue in order to avoid a simple Planning application, though.
I don't like flat roofs...never ceases to amaze me, the complications and compromises that people will pursue in order to avoid a simple Planning application, though.
I have a 2 acre curtilage so I can build big sheds without issue under PD, I'm in the greenbelt so I'd struggle under planning.
I am going to try for some homes on part of it but I think I want to build this first - if only to have more sqft to trade off.
V8RX7 said:
I don't like flat roofs
Well, that's a pity, because at 10 degree pitch, that's what you're designing, structurally, as near as makes no difference.V8RX7 said:
...I can build big sheds without issue under PD, I'm in the greenbelt so I'd struggle under planning.
You shouldn't.Any competent Planning Officer should be looking at any proposal with half an eye to asking themselves "how different is this from what would be allowed under PD, and what additional harm is there that might make it unacceptable where the PD is not?".
If you're not confident that the Planning Officer is competent, then write them a brief supporting Planning Statement that reminds them of this.
In many cases, it's easy to make a case that there can be less harm (because you are according with vernacular character) in a taller, non-PD compliant design than there would be going down the PD route.
Edited by Equus on Monday 12th November 13:23
I've just done a new build village hall with a 21.0m length main hall and 8.21m span.
used simple portal frames - 152x89x16 UB rafters, 152x152x30UC columns and 127x76x13UB ridge beam, roof infilled with 150x50 rafters lapped over and hung off the ridge beam.
By the time the roof was boarded and insulated we had a tiny haunch to detail but nothng you would notice.
It was cheap and effective - I reckon that's the way to go.
used simple portal frames - 152x89x16 UB rafters, 152x152x30UC columns and 127x76x13UB ridge beam, roof infilled with 150x50 rafters lapped over and hung off the ridge beam.
By the time the roof was boarded and insulated we had a tiny haunch to detail but nothng you would notice.
It was cheap and effective - I reckon that's the way to go.
Equus said:
Any competent Planning Officer should be looking at any proposal with half an eye to asking themselves "how different is this from what would be allowed under PD, and what additional harm is there that might make it unacceptable where the PD is not?".
If you're not confident that the Planning Officer is competent, then write them a brief supporting Planning Statement that reminds them of this.
I know you're right in theory but in practise that's not my experience, only twice in approx 100 planning applications have I met a competent / helpful Planner.If you're not confident that the Planning Officer is competent, then write them a brief supporting Planning Statement that reminds them of this.
Most of the time they may as well be a robot that just says"no"
I was offered a job by my architect when he saw my last Planning Statement - there was still zero discussion and a flat "no"
(I won on Appeal)
Lotobear said:
I've just done a new build village hall with a 21.0m length main hall and 8.21m span.
used simple portal frames - 152x89x16 UB rafters, 152x152x30UC columns and 127x76x13UB ridge beam, roof infilled with 150x50 rafters lapped over and hung off the ridge beam.
By the time the roof was boarded and insulated we had a tiny haunch to detail but nothng you would notice.
It was cheap and effective - I reckon that's the way to go.
Yes that sounds very similar to my last extension, except it didn't have a ridge beam just steel purlins - within the rafters to reduce the thickness, as I had to get it below a window.used simple portal frames - 152x89x16 UB rafters, 152x152x30UC columns and 127x76x13UB ridge beam, roof infilled with 150x50 rafters lapped over and hung off the ridge beam.
By the time the roof was boarded and insulated we had a tiny haunch to detail but nothng you would notice.
It was cheap and effective - I reckon that's the way to go.
I placed the 152mm in the cavity but then had the internal blockwork stop at each one - in hindsight I should have increased the cavity to 152mm
Rosscow said:
Blimey, 10 degrees. That's low. I'm presuming a dual pitch? Is it worth the effort? The 'vault' will only be around 700mm in the centre.
I think so, my kitchen was height limited by a window and was 10 degrees
I thought flat would look low and dull / cheap internally and externally.
I don't want it too high either as I have to heat it and I'm mean
Edited by V8RX7 on Monday 12th November 17:15
V8RX7 said:
I know you're right in theory but in practise that's not my experience, only twice in approx 100 planning applications have I met a competent / helpful Planner.
Most of the time they may as well be a robot that just says"no"
Well, you're doing something wrong, then, as I work all over the UK, and seldom experience such difficulties.Most of the time they may as well be a robot that just says"no"
I've just got Planning Permission on a relatively very large annexe (two art studios and a guest suite, in the grounds of a new-build 5-bed house), using pretty much exactly the arguments set out above (paraphrased: "if you don't approve it, we'll just build a worse design that's PD compliant, and if you try to withdraw our PD rights, we'll appeal and you'll lose all control, anyway").
It's how you put it to them, of course: it was dressed up in Planning Policy and polite words, but the meaning was obvious.
Equus said:
Well, you're doing something wrong, then, as I work all over the UK, and seldom experience such difficulties.
I've just got Planning Permission on a relatively very large annexe (two art studios and a guest suite, in the grounds of a new-build 5-bed house), using pretty much exactly the arguments set out above (paraphrased: "if you don't approve it, we'll just build a worse design that's PD compliant, and if you try to withdraw our PD rights, we'll appeal and you'll lose all control, anyway").
It's how you put it to them, of course: it was dressed up in Planning Policy and polite words, but the meaning was obvious.
The majority I wasn't in control merely the frustrated Land buyer for various National Housebuilders I have been for my own stuff and find they simply won't speak to me at all - they don't have time to do pre planning and it's "too early" and then "too late" to discuss anything during the 8 weeks.I've just got Planning Permission on a relatively very large annexe (two art studios and a guest suite, in the grounds of a new-build 5-bed house), using pretty much exactly the arguments set out above (paraphrased: "if you don't approve it, we'll just build a worse design that's PD compliant, and if you try to withdraw our PD rights, we'll appeal and you'll lose all control, anyway").
It's how you put it to them, of course: it was dressed up in Planning Policy and polite words, but the meaning was obvious.
I tried an Architect and whilst they would talk to him, he received conflicting advice - costing me thousands to get absolutely no where
V8RX7 said:
I tried an Architect and whilst they would talk to him, he received conflicting advice - costing me thousands to get absolutely no where
Try someone who knows something about the Planning system, next time, then - and surprisingly that's not the majority of Architects. They have no training in it, and very little exposure to it.Yes, there are instances where Planning departments will try to stonewall you completely, but they're very much in the minority - and they now have an obligation not to under National Planning Policy, hence the introduction of 'positive and proactive' statements on Planning decision notices.
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