Extension roof design dilema

eggerb

I am planning a single storey extension to a two storey house but I am in a right dilemma as to how I should have the roof constructed. I've attached a picture of the existing roofs. I've spoken to an architect, an engineer and several builders and they all have different ideas on what would work best.

There is currently a lean-to roof with hips at the side of the building and a small lean-to with gable ends at the rear. My proposed extension will fit between these two roofs. (I am proposing to put the extension where the shed is in the current picture.)

Some builders have recommended continuing out the existing side extension and running in the small lean to. One talked about taking the existing small lean-to off and joining it to the side lean-to. (This was the preference of an architect I spoke to). I don't really like the aesthetic appeal of any of the lean-to options as it will be single aspect and not as appealing inside. Additionally, I would loose a tiny bit of height as the wall nears the boundary as it will project 1 metre beyond the existing side lean-to.

I like the idea of something like in my proposed elevation drawing (gable or hipped) as it will look good inside and outside. However, I think I would probably end up with valleys and maybe that is not ideal? (This was the preference of a structural engineer I spoke to). Some builders have suggested that this will look a bit peculiar as I will be joining two different types of roofs. Does anybody have any suggestions/thoughts on what I should go for?

Side & Rear Elevation


Picture of two roofs

TCP/IP_King

eggerb wrote: »

... suggestions/thoughts on what I should go for?

I'd go for the proposed rear elevation - it looks better, but more expensive to build I would suspect (the valley).

Check out that ridge line on the proposed side elevation, it doesn't look in the right place.

onq

If you go for the preferred one you may need permission.

The exempted development regulations are funny about not exceeding the height of existing buildings ridge or eaves.

I'd run it past your local planning officer before you decide.

FWIW

ONQ.

Poor Uncle Tom

onq wrote: »

If you go for the preferred one you may need permission.

The exempted development regulations are funny about not exceeding the height of existing buildings ridge or eaves.

I'd run it past your local planning officer before you decide.

FWIW

ONQ.

This isn't an issus here, as the eaves and ridge are those of the main building and the proposals do not come near them.

RKQ

Both options seem to work, so my advice is go for the rear design that appeals to you!:) At the end of the day you have to live there.

I'd assume the gable design might be a bit more expensive but it does look better ( in the drawing at least )

onq

Poor Uncle Tom wrote: »

This isn't an issus here, as the eaves and ridge are those of the main building and the proposals do not come near them.

I'm afraid I cannot agree here Tom.

This is a new build to the side of the existing main house [2-storey pitched roof with eaves to the rear] and lies wholly behind an existing lean to roof]

The proposed extension lies wholly to the side of the main building.

This doesn't appear to be covered by the exempted development regulations [my bold]; -

CLASS 1
The extension of a house, by the
construction or erection of an extension
(including a conservatory) to the rear of
the house or by the conversion for use as
part of the house of any garage, store,
shed or other similar structure attached to
the rear or to the side of the house.

As this is minor and assuming the neighbours don't object, the planners may not be prompted to take action, but one is never certain in such cases. The degree of public approbation can sometimes have a bearing on whether or not the local authority will or won't take action.

To answer one of the questions asked, there will be an awkward "feathering away to nothing" detail visible from the front between the gable face of the new roof and the existing roof.

I'd be tempted to run the existing lean to roof on, perhaps extending the glazing up to get more light into the new section. I'm assuming the existing wall is intended to run on into the new wall.

HTH

ONQ.

eggerb

Thanks for the replies everybody.

I agree with RKQ and TCP/IP_King that it looks better - definitely from the rear anyway. I'm just concerned that it may look funny from the side with essentially a gable or a hip meeting the [existing] lean to. (A hip on the new roof would work better I think.) The valley also has me wondering if I am making myself problems.

onq wrote: »

... there will be an awkward "feathering away to nothing" detail visible from the front between the gable face of the new roof and the existing roof.

Could you elaborate on this one please onq? That the existing roof will run down into nothing?

Mellor

Sketch it out on plan, roofs are much easier to work out that way.

onq

eggerb wrote: »

Could you elaborate on this one please onq? That the existing roof will run down into nothing?

Hi eggerb

There is no mystery here although if it appears so it must be through my poor description of things.
You are intending to span the distance between the main house and the side wall of the extensionwith two different roof forms.
Given the information you've provided, this looks like the same plan dimension

A lean-to roof rising from the same eaves to the same height where it abuts the main house as a gable ridge will see the gable ridge projecting above it in the mid point.
The proposed gable is actually shown as being higher again than the lean-to roof so the ridge will be even more prominent.

If you superimpose the new gable roof profile over the existing lean-to roof profile looking from the front, you will see this the triangular "face" I'm talking about.
If you look above the first "o" of "proposed" in "proposed side elevation" you will see this as the vertical line where your gable springs from.

It is this vertical element that will feather away - the important thing is not the feathering away but the visible projection of the gable peak above the existing lean-to.
This is what will get it noticed from the front and may require planning recification or inspire enforcement action.

I hope this clarifies this for you.

Couple of minor points; -

The existing side elevation looks to be incorrectly drawn.
It seems to show the roof of the lean-to running out as far as the rear projection and making a hip roof there.
The photograph clearly shows that this does not happen - the existing rear projection has no hip.
Also the lean-to roof appears to stop at the rear corner of the main house or thereabouts.
The two roofs never meet.

Also try to find out what that little hotizontal section of roof linking the existing rear projection to the proposed gable is meant to be - you can see it just above the "e" in "elevation" in "proposed rear elevation" .

As mellor says, you should sketch it out on plan - and I think he means you should do out a roof plan, as opposed to a wall plan or fouundation plan.
However a roof plan alone won't define this issue - look at it from the side, front and rear and in greater detail to see it.
I know you probably reduced the original to post it here, but even a 1:50 single line drawing will show this clearly.



All this goes to the fact that the projecting ridge of the gable option will be seen from the front.
It is this "seeing it from the front" that may affect whether or not it constitutes exempted development or not.
Also when availing of the exempted development schedule the total area should not exceed 40 sqm in excess of the original plan of the house.

FWIW

ONQ.

eggerb

Thanks for clarifying that for me ONQ and pointing out some of the other discrepancies.