Eaves height vs ceiling height

[oldkettle]

Is there any approximate rule to figure out what wall height I need to achieve a certain ceiling height / eaves height? 

I am trying to figure out how high we need to go to have 2.5m ceilings but still stay within PD rules limit. In our case we dig deep into a slope (about 1000mm) so we have substantially more than standard 2.5m but obviously don't want to anger the neighbours. 

The walls are planned as ICF if this makes a difference. The structure will hopefully be some kind of a warm roof, either fink trusses or SIPs, not sure what will be the cheaper option by the time we get to this. 

 

Thanks in advance. 

Edited October 3, 2021 by oldkettle

[joe90]

I managed to do this with my garage by having large overhanging eaves, gutter at 2.5m and ceiling 2.8m.

[oldkettle]

11 minutes ago, joe90 said:

I managed to do this with my garage by having large overhanging eaves, gutter at 2.5m and ceiling 2.8m.

Thank you Joe. What wall height did you need then? 3m+? As I understand it a lot depends also on where the insulation goes: between and below rafters probably requires less depth than a proper warm roof with insulation above. 

 

Does it also mean eaves are measured at the end of the roof, not above the wall?

By the way, I've found this drawing as an illustration but obviously this is not for the purpose of PD. 

[joe90]

12 minutes ago, oldkettle said:

Does it also mean eaves are measured at the end of the roof, not above the wall?

Correct, the gutter. I was limited to 2.5m for permitted development but wanted a tall door to get my van into the garage and give me a decent internal height as it was also used as a workshop. The roller door mechanism was about 350mm but still gave me 2.5m opening. I had no insulation as it was only a garage/workshop. The large overhang also meant driving rain stayed out of the garage when the door was open ?.my overhang was 500mm.

Edited October 3, 2021 by joe90

[oldkettle]

Oops, it seems the rules say otherwise (which kind of makes sense to be honest) 

 

"Eaves height is measured from ground level at the base of the. outside wall to the point where that wall would, if projected. upwards, meet the lowest point of the upper surface of the roof – the overhang should be ignored for the purposes of measurement. "

 

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/830643/190910_Tech_Guide_for_publishing.pdf

Edited October 3, 2021 by oldkettle

[joe90]

10 minutes ago, oldkettle said:

Oops, it seems the rules say otherwise (which kind of makes sense to be honest) 

 

"Eaves height is measured from ground level at the base of the. outside wall to the point where that wall would, if projected. upwards, meet the lowest point of the upper surface of the roof – the overhang should be ignored for the purposes of measurement. "

Ooh er, didn’t know that, I have always understood it to be the guttering. Perhaps I was lucky my planners didn’t challenge it ?

[oldkettle]

3 minutes ago, joe90 said:

Ooh er, didn’t know that, I have always understood it to be the guttering. Perhaps I was lucky my planners didn’t challenge it ?

Indeed, it's great they didn't, you had enough grief from them. 

[joe90]

Just found what I copied from the planning portal, no mention of measuring height at wall.

 

• 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.
• Maximum height of 2.5 metres in the case of a building, enclosure or container within two metres of a boundary of the curtilage of the dwellinghouse.

 

just found what you quoted above on the gov. Website ?.  Oops. ?‍♂️

Edited October 3, 2021 by joe90

[Gus Potter]

2 hours ago, oldkettle said:

Is there any approximate rule to figure out what wall height I need to achieve a certain ceiling height / eaves height? 

I am trying to figure out how high we need to go to have 2.5m ceilings but still stay within PD rules limit. In our case we dig deep into a slope (about 1000mm) so we have substantially more than standard 2.5m but obviously don't want to anger the neighbours. 

The walls are planned as ICF if this makes a difference. The structure will hopefully be some kind of a warm roof, either fink trusses or SIPs, not sure what will be the cheaper option by the time we get to this. 

 

Thanks in advance. 

Hello Old Kettle.

 

In the spirit of BH and.. the planners.. we are all well intentioned folk. Totally agree we all need to live next to one another.

 

To work this out you need to start from the outside plane of the roof and work back. It's generally accepted that the eaves height for PD is this. Project a line from the outside face of the wall up to the top side of say the roof tiles or roofing felt. This is the eaves height.  The folk that drafted this are not daft!

 

The wicked may add a lean to log store onto the side of their building. Here they (the wicked) would argue that the footprint of the walls complies with PD but the eaves height is say the facia level of the log store. The result would be that you could have a pretty high structure right next to your neighbours. Not very fair as they could do the same to you!

 

The next thing is that the eaves height is normally measured from the natural lowest point of the ground adjacent to the proposed walls. Thus, if you have sloping ground it's measured from the lowest point of the established natural gound level.

 

This to is reasonably well drafted. You get some folk that will "build up their garden" by adding decking or planters and measure from there. For the "enthusiastic reader of the PD rules"  better to take your chances at William Hill. The planners have seen it all and now with google and all the histroric photos?

 

Now you can dig down as what we are considering here is the impact it will have on your neighbours. If you sit the floor say 1.0 m below the existing natural ground level then the height for PD is still taken as that from the natural gound level. With a bit of thought you can probably get what you desire.

 

If you are digging into the slope then you need to put a bit of thought into the SE / Geotechniques design as you are into maybe retaining wall terratory / damp proofing, maybe party wall stuff if not in Scotland.

 

It's all a bit back to front but once you get your outside envelope established then you can work back without having to reappraise.

 

Old kettle hope this helps.

 

 

 

 

 

 

[Dave Jones]

7 hours ago, joe90 said:

Ooh er, didn’t know that, I have always understood it to be the guttering. Perhaps I was lucky my planners didn’t challenge it ?

 

cant be guttering as you could drop it well below the true eaves height if you think about it.

[oldkettle]

9 hours ago, Gus Potter said:

Hello Old Kettle.

 

In the spirit of BH and.. the planners.. we are all well intentioned folk. Totally agree we all need to live next to one another.

 

To work this out you need to start from the outside plane of the roof and work back. It's generally accepted that the eaves height for PD is this. Project a line from the outside face of the wall up to the top side of say the roof tiles or roofing felt. This is the eaves height.  The folk that drafted this are not daft!

 

The wicked may add a lean to log store onto the side of their building. Here they (the wicked) would argue that the footprint of the walls complies with PD but the eaves height is say the facia level of the log store. The result would be that you could have a pretty high structure right next to your neighbours. Not very fair as they could do the same to you!

 

The next thing is that the eaves height is normally measured from the natural lowest point of the ground adjacent to the proposed walls. Thus, if you have sloping ground it's measured from the lowest point of the established natural gound level.

 

This to is reasonably well drafted. You get some folk that will "build up their garden" by adding decking or planters and measure from there. For the "enthusiastic reader of the PD rules"  better to take your chances at William Hill. The planners have seen it all and now with google and all the histroric photos?

 

Now you can dig down as what we are considering here is the impact it will have on your neighbours. If you sit the floor say 1.0 m below the existing natural ground level then the height for PD is still taken as that from the natural gound level. With a bit of thought you can probably get what you desire.

 

If you are digging into the slope then you need to put a bit of thought into the SE / Geotechniques design as you are into maybe retaining wall terratory / damp proofing, maybe party wall stuff if not in Scotland.

 

It's all a bit back to front but once you get your outside envelope established then you can work back without having to reappraise.

 

Old kettle hope this helps.

Thank you Gus

 

I am pretty sure that the height is measured from the highest natural point, not the lowest though, at least in England. 

I also have done soil test and involved SE for insulated raft design already. 

 

But my main question is different. I want to understand how high my eaves have to be for a specific ceiling height. Is there a way to say "for 2500 ceiling you will need at least 2750 walls and 2900 or 3200 eaves"? Again, we are talking about well insulated building, not a shed. 

[joe90]

4 minutes ago, oldkettle said:

But my main question is different. I want to understand how high my eaves have to be for a specific ceiling height

Despite my error with measuring eaves ?, decide on your ceiling height, add ceiling joist, rafter, tiles but you need to draw this up to get an accurate answer. However if you had skeilings I.e. ceiling joists not on wall plate but further up roofing joists you could get higher ceiling heights ?.

[Big Jimbo]

Old Kettle. I agree that in england it is measured from the highest natural ground point. I think you will have to do some working out of the materials you are going to use in order to work out your height. To be honest i think that the 2.5 eaves is very out of date. Especially when you consider modern, warm flat roofs. If you think about a flatroof, internal height 2440mm + roof joists 220mm + Sterling board 22mm + pir 150mm + sterling board 22mm + epdm 2mm. None of my flat roof extensions that i have done on my 3 daughters houses have anything like a 2.5m eaves height. Perhaps flat roofs have different rules ?

[oldkettle]

6 minutes ago, joe90 said:

Despite my error with measuring eaves ?, decide on your ceiling height, add ceiling joist, rafter, tiles but you need to draw this up to get an accurate answer. However if you had skeilings I.e. ceiling joists not on wall plate but further up roofing joists you could get higher ceiling heights ?.

Thanks Joe

I look at roof trusses and they seem to sit on top of the wall plate which is good enough for me. Then yes, as you said, rafter, insulation, battens and tiles. I suspect 500mm should be enough to cover this. 

[oldkettle]

4 minutes ago, Big Jimbo said:

Old Kettle. I agree that in england it is measured from the highest natural ground point. I think you will have to do some working out of the materials you are going to use in order to work out your height. To be honest i think that the 2.5 eaves is very out of date. Especially when you consider modern, warm flat roofs. If you think about a flatroof, internal height 2440mm + roof joists 220mm + Sterling board 22mm + pir 150mm + sterling board 22mm + epdm 2mm. None of my flat roof extensions that i have done on my 3 daughters houses have anything like a 2.5m eaves height. Perhaps flat roofs have different rules ?

Thank you. 

 

Extensions are different AFAIK. Re. 2.5 limit, I think this is to minimise the impact on the neighbours. In our case they are even higher up the slope hence we are not going to upset them unless we really push it. I've removed a row of 4m+ conifers between us earlier this year so they are quite happy. 

[saveasteading]

30 minutes ago, oldkettle said:

height is measured from the highest natural point, not the lowest

I never found a planner who knew what, if anything, was the definition. Once or twice had heights queried by neighbours (there was nothing wrong) so had the discussions.

1. Don't cheat

2.. Don't worry about the odd 100mm as long as you can measure properly somwhere.

[oldkettle]

2 hours ago, saveasteading said:

I never found a planner who knew what, if anything, was the definition. Once or twice had heights queried by neighbours (there was nothing wrong) so had the discussions.

1. Don't cheat

2.. Don't worry about the odd 100mm as long as you can measure properly somwhere.

 

Absolutely. I have checked the rules for my own piece of mind and also because with a 1300mm difference in levels between corners we would be in a difficult situation. The way things stand eaves are going to be about 2m at the back where neighbours can see it and nobody cares about the front. 

[saveasteading]

2 minutes ago, oldkettle said:

1300mm difference in levels between corners

That is a lot, so I would say don't push your luck. If no dimensions are stated then it would have to be within reasonable accuracy with scaling ('do not scale  will not apply)

[oldkettle]

36 minutes ago, saveasteading said:

That is a lot, so I would say don't push your luck. If no dimensions are stated then it would have to be within reasonable accuracy with scaling ('do not scale  will not apply)

Apologies, not sure I understand. 

Just to clarify : this is planned as PD even though the overall size is relatively large. 2m from boundary etc. We will ask for lawful development certificate later. 

 

Do you mean 3m eaves in the lowest corner can cause issues? I was not going to try and hide anything as from what I read including an appeal decision the rules are clear enough. 

[epsilonGreedy]

15 hours ago, joe90 said:

?.my overhang was 500mm.

 

 

If I was your planning officer I would have demanded that you fit a large Swiss cuckoo clock on the gable end and performed 5 minutes of yodeling at noon each day.

[saveasteading]

45 minutes ago, oldkettle said:

Apologies, not sure I understand.

I was not being specific, just joining in the discussion on how much discrepancy might  bother a planner.