Granny annex eves and ridge height?

[Paul burt]

hi,
Just in the process of applying for planning approval for a 42.5m2 granny annex, I’m attempting to do the basic drawings myself, one to save some money and two, to be sure we get approval before getting to heavily involved in a project that may not happen for some time.
Having spoken to our local authority, the guidelines are pretty straight forward I.e max eves height of 3mtrs, max ridge height of 4mtrs etc, question is if we want a ceiling height of 2.4, what would be the wall plate height from FFL and what would be a standard overhang for a 4x12 pitch roof to give me the eves height figure?
Many thanks
Paul.

 

[Nakajo]

What difference does the overhang make?

 

[^woody^]

If you are applying for planning permission then eaves and ridge can be any height you like.

 

[Paul burt]

Just in reply, the local planning department have stipulated the eves and ridge maximum heights for this project based on where it is in regards surrounding building etc, the overhang width effects the eves height.
Can’t seem to find any detail on the net concerning ceiling height to eves height etc, not sure what a standard soffit width would be 100mm, 150mm?
Need some deffinate figures not only for the drawings but for my own peace of mind, that I’ve got it right and it will all work out as intended.

 

[tony1851]

It depends on what you - and the planning officer - mean when defining "eaves".

One pictorial view is shown on page 12 of the DCLG Permitted Development Rights for Householders; Technical Guidance. , but that might not be
precisely what the planning officer calls 'eaves'.

It is also no good referring to the height above ffl, if we don't know the difference in height between floor level and ground level (if ground level is the level you are measuring eaves height from).
Wouldn't it be easier for you just to have proper plans drawn?

 

[Paul burt]

My intention is to gain planning approval with basic drawings, then employ an architect for building regs etc, once we decide to make a start on it which may possibly be 6-12 months time.
At this stage we’ve only talked informally with the planning department, the “can’t see any reason why not” is obviously very different to gaining approval, if for instance we were asked to reduce in size or to have no windows facing neibouring properties, the build is probably not viable.
Ps. The FFL is 150mm above ground

 

[^woody^]

If you draw a triangle on top of a rectangle, you will notice that the length of the triangle base and the angle of the opposite and adjacent sides determine the [soffit] overhang.

 

[Paul burt]

Having checked the building regs guide, it’s all become a bit confusing, seems the measurement required is the distance from ground level to the point where a vertical wall would meet the under side of the roof if you didn’t have facia and soffits, the actuall height of the eves could be very different to this given a big overhang and wide soffit but if that’s what is required so be it, at first glance this measurement means nothing if below the 3 mtr limit.

 

[^woody^]

I'd suggest involving someone who knows what they are doing now rather than later.

You don't really want to get planning permission for a design that can't actually be built when the poor person you choose to do the building regs drawings comes along.

 

[Paul burt]

Just to repeat my original question, can someone give me the wall plate height on a single storey dwelling with 2400 high ceilings, please?

 

[tony1851]

The top of your wall plate will be 2400 above floor level (or add 10mm for ceiling plaster if being precise).

 

[Paul burt]

Yes I’d just worked it for myself, pretty obvious really

 

[^woody^]

Can someone tell me the relevance of wall plate height to eaves height? Thanks.

 

[tony1851]

Can someone tell me the relevance of wall plate height to eaves height? Thanks.

Nope. You're welcome.

 

[^woody^]

Pfft. I won't be asking you again.