# internal height with pent roof



## Lazurus (16 Feb 2021)

Due to planners I have had to adjust my ongoing application and lower the eaves height to 2.5m, the question is over a 5m span and allowing for a warm roof space what is the likely internal height at the lowest point as I stand 1.84m in socks and getting worries I am not going to have enough head room. Was looking at a 8 degree slope with EDPM roof over either sips or tarditional warm roof with celotex construction.
Maths and geometry not a strong point


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## TheUnicorn (16 Feb 2021)

not sure if it is an option, but I wonder if you could do a two stage roof, shallower angle nearer the top, steeper angle nearer the bottom. Essentially half a gambrel roof How to Build a Gambrel Roof


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## RobinBHM (16 Feb 2021)

You will struggle to get enough height with a pitched roof.

Why don't you do a flat roof - which in reality needs a fall of about 1 in 50 ish. ( 1 in 80 is theoretical, but allowing for seams and inaccuracies in construction 1 in 40 is considered practical min for felt - and I've always found 1 in 50 or 60 fine for GRP or EPDM).


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## Sachakins (16 Feb 2021)

Why pent roof?
Standard central pitch at 2.5m gives higher walls than pent roof.
Full fĺat roof probably easiest though, as above.


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## Fitzroy (16 Feb 2021)

An 8 degree slope on a pent design is a lot. It would lose you 70cm over a 5m span. A 1:50 fall would lose you 10cm over a 5m span.


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## Jameshow (16 Feb 2021)

Any chance of digging gown a little? Is that allowed? 

Do planners ever check permitted developments.

I guess it's more the nimby neighbours... 

Cheers James


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## Ollie78 (17 Feb 2021)

My Mum has a large log cabin thing. The way they got around the height restrictions was to do the roof with the "point" offset.
So the peak of the roof is at about a quarter of the width. 
So one short steeper bit and a longer shallow bit. ( that is a poor explanation I think but you get the idea ). 
I can stand up in most of it, I am 190cm. I just need to avoid one beam.
The shed is probably 4m by 6m with the pitch on the short side.

Ollie


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## eribaMotters (17 Feb 2021)

Lazarus,
I'm guessing you may be building of an existing structure. Do you have to go pent roof. 
The attached photo is of my previous workshop. This was 5m wide and under 4m at the ridge. Eaves height was around 2.3m. It was in 100 x 50 studwork construction sitting on a 3 high brick plinth over a concrete raft over trench footings. The 5m span was possible with this as 1/3 of the rise on the rafters I had ceiling joist tieing the timbers across both pitches. This gave an internal ceiling height of about 2.5m once the screed was down and an insulated roof void.




Colin


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## shed9 (17 Feb 2021)

Do bear in mind that eaves height is the theoretical line the wall will hit on the upper surface of the roof and not the internal height. Your question is also dependent upon the actual depth / thickness of the roof, the trusses, any subsequent insulation and any boarding out - not to mention anything fixed to the ceiling as well like lighting.

Apologies if I missed previous comments on this specific subject but your original message is a little confusing. Are you complying with permitted development or advice from an actual planner?


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## Lazurus (17 Feb 2021)

I went for a flat / pent roof to match existing garages in the area, I initailly went for a 3m height but this has been rejected so i now have to work to 2.5m. It will be a new build brick and block with the front being clad in Hardie board or similar again to match existing structures and building in the area. The architect has resubmitted with the 2.5 to apease the planners but i have my concerns over the internal height.


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## TheUnicorn (17 Feb 2021)

do the architects drawing not give you dimensions for the internals?

My instinct is always to avoid flat roofs, too much sitting water, if its not running straight off it is finding any weakness in the seal and eventually leading to the inevitable leak.


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## shed9 (17 Feb 2021)

Lazurus said:


> I went for a flat / pent roof to match existing garages in the area, I initailly went for a 3m height but this has been rejected so i now have to work to 2.5m. It will be a new build brick and block with the front being clad in Hardie board or similar again to match existing structures and building in the area. The architect has resubmitted with the 2.5 to apease the planners but i have my concerns over the internal height.


I just noticed your signature / location and I'm guessing you do need planning hence the submission. As above, your architect's plans should give you an idea or at the very least they should be able to advise.
Is the 2.5m the upper eaves height? I suspect most people (myself included) assumed that was the lower height in your original post linking it to the remit of permitted development which of course is moot within a National Park. You don't need a huge pitch for a pent style roof but a 5m span is a fair width and it's dependent on that pitch and construction of the roof.


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## Lazurus (17 Feb 2021)

The only plans I have seen are attached, albeit they will now be ammended to 2.5m I contacted the architect with the quesry and he states he envisages a vaulted ceiling under the monpitch roof therefore the internal height will be 2m at the lowest point and 2.8 at the heighest - I am totally confused now!!!!


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## HOJ (17 Feb 2021)

Lazurus said:


> I am totally confused now!!!!



So am I, I will wait with anticipation as to how the "Architect" is going to engineer this, and deal with rainwater/snow, 
can't see any guttering or down pipes shown, perhaps you will have a water feature as well.


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## Sachakins (17 Feb 2021)

Are you getting confused with roof height and eaves height, see text below.

For the purpose of measuring *height*, the *eaves* of a house are the point where the lowest point of a *roof* slope, *or* a flat *roof*, meets the outside wall. ... *Eaves height* is measured from the ground level at the base of the outside wall to the point where that wall would meet the upper surface of the flat *roof

it makes sense why the drawing is incomplete, it only a submission for planning not a build drawing.
The roof pitch will rise up from here, hence the description of it having a vaulted roof.




*


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## shed9 (17 Feb 2021)

HOJ said:


> So am I, I will wait with anticipation as to how the "Architect" is going to engineer this, and deal with rainwater/snow,
> can't see any guttering or down pipes shown, perhaps you will have a water feature as well.


+1. The architects design shows a flat roof unless of course the front facias hide the slope.


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## Robbo60 (18 Feb 2021)

I'm confused too - not unusual! If the eaves are 2.5 and you go with a pitched roof, the trusses will sit on be notched in/hangers to the eaves. This means you will only lose at most the depth of the truss - say 200mm that leaves 2300 clearance - or am I missing something? Also I would have thought the drawing submitted to the planners would have to show the roof style, especially in a conservation area??


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## pils (18 Feb 2021)

this would be my take on the situation:




meaning one has 236mm in which to create a ceiling/roof/pent angle with 2122/1900 internal height. ALL approximate!!!


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## shed9 (18 Feb 2021)

Assuming the end design is a pent (with the lower eaves side being the back wall) then placing benches, desks, utilities, etc along that lower ceiling edge / wall would reduce the lower height restrictions by at least 600mm into the floorspace - if that makes sense?


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## Lazurus (21 Feb 2021)

Thanks everyone, starting to make sense now


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