Outbuilding regulation 3M 'any other roof' height reference.

[UniqueID]

Hello,

I have read and understand the current regulations regarding maximum heights for outbuildings, aside from the reference to the 3M maximum height for what they refer to as 'any other roof'.

I am looking to build a timber shed/workshop that will be more than 2M from the boundary fences, but am specifically interested in gaining as much internal height as is possible as I need 2.6M internal height clearance from floor to underside of any joist/noggins and therefore need to calculate approximate distance in from the walls that I could achieve this sort of clearance.
I need this 2.6M clearance across a 3.1M floor area inside (widthways), so the varying pitch angles from the 2.5M eaves will naturally affect the overall size of the shed/workshop construction to allow this internal clearance.

So I get the maximum eaves height at 2.5M and if I take that up to the maximum 4M ridge height for a dual pitch apex roof, I could calculate what I need to achieve - but a 4M ridge is a pretty substantial construction, so I am wondering what is meant by the 3M maximum height for 'any other roof'?

The way I am seeing it, any mono-pitch type of roof will always technically have a measureable eave at the highest point of the pitch and this would need to be 2.5M as a maximum - so when does the 3M option come into play if it is not considered dual pitch which would then allow a 4M height?

I am probably clutching at straws perhaps due to not understanding alternate standard roof descriptions, but does this theoretically mean you could have 2 x eaves @ 2.5M, then a STEEP pitch to 3M (as steep as possible to end up with a sort of ridge that would fall pretty much just inside the line of the eave measurement) from one of the eaves and pitch the roof from there down to the other 2.5M wall/eave ... or even have BOTH of the 2.5M eaves pitching up steeply to 3M and then have a completely flat roof @ 3M high?

My terrible MS-Paint sketch hopefully shows what I am getting at?

Thanks for any help.

Clutcher

Untitled

• UniqueID
• 30 Mar 2015
• 1

 

[ban-all-sheds]

My terrible MS-Paint sketch

SketchUp is still free

 

[freddiemercurystwin]

Yes I have to say I looked at this thread and it needs some clarification .....

 

[UniqueID]

Sorry - been away for a week, so missed the replies.

I will download sketchup, although I shouldn't have blurred things (even more) by attempting a sketch as I do not have a specific plan in mind.

My main question/confusion is concerning the standard outbuilding regulations that state (for an outbuilding that will be MORE than 2M from any existing boundary etc):

"Outbuildings and garages to be single storey with maximum eaves height of 2.5 metres and maximum overall height of four metres with a dual pitched roof or three metres for any other roof"

So I get the 4M ridge height for a dual pitch with eaves of 2.5M, but what I am not understanding is what sort of roof could be classified as "any other roof" to be allowed a 3M maximum height with the maximum eaves height of 2.5M ... ?

It is my understanding that the eave height is measured at the point of where the line of the wall would meet the TOP side of the roof, so surely a completely flat roof AND a mono-pitch roof have to be (theoretically) 2.5M maximum height as well (seeing as the eave measurement has to be 2.5M ... ?)

I must apologise for making this such a long and complicated question, but the reason I am asking is I have a prefabricated modular booth/room that is made up of steel panels that are 2.5M tall, 50cm wide and 10cm thick (filled with insulation) and I would like to set this up in the garden ... once constructed it will measure 5.5M in length, by 3.1M in width and stand 2.5M high.

So to fit a 2.5M high construction inside an outbuilding without needing building regs, I am trying to calculate what size outbuilding I would need - and the problem is when starting at a 2.5M eave, I need the roof pitch angles to be as steep as possible in order to clear the 2.5M steel room as soon as possible (so as to keep the overall width of the timber outbuilding as narrow as possible for both complexity of constructions sake as well as to avoid needing to lop down some beautiful and mature trees!).

So if I chose the 4M dual pitch option, I could calculate the overall outbuilding width, but a 4M high outbuilding is quite a large beast for the neighbours to accept, so I am trying to understand how I could possibly look into a 3M roof height (that is not a dual pitch) with 2.5M eaves?

Hope this makes things a bit clearer?

Thanks for any help - I do appreciate anyone's time taken to trawl through this and offer any pointers.

Regards
Clutcher

 

[UniqueID]

I can see that my ramblings probably make things even more blurry.

Perhaps the simpler question is, how do you build a flat roof (or a mono-pitch type roof) to a height of 3 metres but keep the eaves to a height of 2.5 metres?

Thanks
Clutcher

 

[oldbutnotdead]

Ah.

So you need to cover your modular whatever that is 3100 wide and 2500 high.

I think you're reading too much into the regs. A monopitch roof is going to be a single pitch (ie no changes in pitch across the roof), highest point 3000, max height at eaves 2500. Dual pitch again is easy- max ridge height 4000, max eaves height 2500.
Your Dutch barn roof is neither (not a monopitch and not a dual pitch) so might be allowable but will be a pain to build- you'd end up with trusses which will lose you all your lovely headroom

Structure-wise you'll be best off with a prefab steel portal type shell (because the rafter depth will be much less than if you use timber or trusses or whatever.

Do you need to walk around this booth thing?- if you do you need to allow another metre either side so your span is now going to be 5100

If you use a prefab steel thing you need to allow about 150 for depth of corrugated metal and purlins so your max internal height at the eaves is now 2350, max internal height at ridge of monopitch 2850 so 150/500 or 30% of the span will be too low - at 5m span that's 1500mm that is too low which leaves 3500 available for your box if it can be rammed against the high wall (well not rammed against but only 400 clearance).

Of course you could always have your internal floor level below ground level...... or go for a dual pitch roof, just because max permissible is 4000 doesn't mean you have to build to 4000.

Assuming the same sums (5100 span) and tin construction;
Internal eaves height 2350, internal ridge height 3000 so 150/650 * 2550 (or 588mm) of the span would be too low each side. Which is perfect- you can centre the box so you can walk all the way round it and you've done it all inside a max external height of 3150.

Trigonometry comes in very handy at times.....