# Max size of extension to 3-bed semi without requirement for planning permission



## chlipps (14 Jan 2010)

We live in a 3-bed semi detached house. We are considering an option of an extension to the rear of the house rather than move to another. Can someone clarify what size extension can be attached to the back of a 3-bed semi without planning? 

I acknowledge the extension must also meet building regs and need competent person for same but may decide to avoid planning bottleneck if the additional space allowed without planning would meet our requirements

Thanks in advance of any feedback


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## onq (14 Jan 2010)

40 sqm, 12sqm of which can be on 1sr floor level, depending on your neighbours, your roof height and design, etc.

This assumes the plan of the house that permsision was obtained for hasn't been extended previously.

This assumes that you're not reducing your rear open space below 25sqm and your windows comply.

You should always check with the planning officer and the development plan for your area.

You should also check with the DOE re the building regulations to ensure you comply.

Don't be worrying about planning applications - 14 weeks well spent usually. 

ONQ.

[broken link removed]


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## chlipps (16 Jan 2010)

Thanks ONQ for detailed response

We are thinking of ground floor extension only from current open plan kitchen/dining area. Not planning on first floor extn. Our ground floor kitchen/dining area is currently L shaped. Part of the L is currently single story with roof sloping south. We are thinking of pitched roof extension to close the L but extend further back (hope not confusing) and the slope of the pitched roof on this extension would be 90 deg to current kitchen element (roof of extn slopes east/west) With as much glass as possible in it, french doors etc,, The existing back window and back door would be removed opening up the extension to the existing space.

I think I will contact the planning officer as you suggest to see if extension is possible. And from there I think I will need to get some plans drawn up as this entension would be right next to neighbours dividing wall. Dont want water from extension roof going over the wall and at same time dont want separate wall beside the boundary wall as this would be area where debris collect and also minimises the space created in the extension. Not sure how feasible it would be to have the existing dividing wall as one leaf of cavity of extension as then roof water will drain on neighbours side 

The kitchen element single story was part of original plan so this would be first extn.

In your post above you mention 25 sqm and windows comply... No issue with the 25sqm, but what you mean by 'windows comply'?.

Thanks again for your feedback


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## picorette (16 Jan 2010)

For windows to comply with the exemption criteria,  any window proposed at ground level in the extension cannot be less than 1 metre from the boundary it faces.


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## chlipps (16 Jan 2010)

I assume that exemption would also apply to a roof light. i.e. we would not be allowed put a roof light on the part of the roof that slopes to neighbour as that would be within 1m. (we are only planning on roof light on east slope only for privacy reasons)

Thanks for quick response


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## picorette (16 Jan 2010)

chlipps said:


> I assume that exemption would also apply to a roof light.



Thats an interesting one. The exact wording of the exemption regulation is:

Any window proposed at ground level in any such extension shall not be less than 1 metre from the boundary it faces.

Is a rooflight a window? Open to interpretation, and probably best clarified with your Planning Authority.


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## chlipps (18 Jan 2010)

Thanks Picorette. I will check as suggested


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## onq (18 Jan 2010)

chlipps said:


> <snip>And from there I think I will need to get some plans drawn up as this entension would be right next to neighbours dividing wall. Dont want water from extension roof going over the wall and at same time dont want separate wall beside the boundary wall as this would be area where debris collect and also minimises the space created in the extension. Not sure how feasible it would be to have the existing dividing wall as one leaf of cavity of extension as then roof water will drain on neighbours side
> 
> The kitchen element single story was part of original plan so this would be first extn.
> 
> ...



I'm afraid I got lost two lines into your description. 
Now I know why they say a picture is worth 1,000 words...

You're very welcome re the advice offered, limited, non-exhaustive and remote from the action though it might be.

May I suggest you approach your neighbour with a view to building on the boundary.
This agreement could be based on a detailed drawing of what you're proposing with dimensions.
This level of detail avoids later complications and it ensures that your builder will be in no doubt about what is required of him on site.

You could offer a quid-pro-quo arrangement:

you build a parapet wall either as a cavity as you describe or perhaps in solid blockwork with external insulation and/or render
your neighbour can strip the insulation and/or render  and take support off the wall should they decide to extend
you get access to perform the build initially and for later at agreed times to paint and or repair the wall.
This may seem heavy-handed to some but it really needs a properly drawn up and witnessed legal agreement to keep working smoothly should the houses ever change hands.

It may come to nothing but its one way to avoid the debris-gathering space you describe above.

As picorette suggests, check with the planning authority regarding the rooflights, because each authority can interpret things differently.
My own understanding that a rooflight may not be a window in that it does not "face" a boundary but skywards, but your local planning officer may take a different view.
The rooflight more than likely will be not less than 1.0M away from the boundary anyway because you'll probably place it at least 900 off the inner face of the wall nearest the neighbour. That plus the wall thickness will mean it should be 1.0M from the boundary.
The distance issues re ground floor windows involve ventilation, light and leaving a side passage for rear access - 900mm would probably do, but not less than 1.0M is what's required without permission.

One issue arising may be your loss of privacy if, depending on the slope of the roof, the neighbours can look in on you through your rooflights.
BTW my original comment about windows related more to the 1st floor windows which are far more restrictive, see 6(b) below:

_6 (b) Any window proposed above ground level in any such extension shall not be less than 11 metres from the boundary it faces._

HTH

ONQ

[broken link removed]

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Extract from the Planning and Development Regulations 2001 being S.I. No. 600 of 2001 at:

http://www.irishstatutebook.ie/2001/en/si/0600.html
_

SCHEDULE 2
Article 6
Part 1

Exempted Development — General

Column 1

Description of Development

Development within the curtilage of a house


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.

------------------------------------------------

Column 2

Conditions and Limitations

1. (a) Where the house has not been extended previously, the floor area of any such extension shall not exceed 40 square metres.

(b) Subject to paragraph (a), where the house is terraced or semi-detached, the floor area of any extension above ground level shall not exceed 12 square metres.

(c) Subject to paragraph (a), where the house is detached, the floor area of any extension above ground level shall not exceed 20 square metres.

2. (a) Where the house has been extended previously, the floor area of any such extension, taken together with the floor area of any previous extension or extensions constructed or erected after 1 October 1964, including those for which planning permission has been obtained, shall not exceed 40 square metres.

(b) Subject to paragraph (a), where the house is terraced or semi-detached and has been extended previously, the floor area of any extension above ground level taken together with the floor area of any previous extension or extensions above ground level constructed or erected after 1 October 1964, including those for which planning permission has been obtained, shall not exceed 12 square metres.

(c) Subject to paragraph (a), where the house is detached and has been extended previously, the floor area of any extension above ground level, taken together with the floor area of any previous extension or extensions above ground level constructed or erected after 1 October 1964, including those for which planning permission has been obtained, shall not exceed 20 square metres.

3. Any above ground floor extension shall be a distance of not less than 2 metres from any party boundary.

4. (a) Where the rear wall of the house does not include a gable, the height of the walls of any such extension shall not exceed the height of the rear wall of the house.

(b) Where the rear wall of the house includes a gable, the height of the walls of any such extension shall not exceed the height of the side walls of the house.

(c) The height of the highest part of the roof of any such extension shall not exceed, in the case of a flat roofed extension, the height of the eaves or parapet, as may be appropriate, or, in any other case, shall not exceed the height of the highest part of the roof of the dwelling.

5. The construction or erection of any such extension to the rear of the house shall not reduce the area of private open space, reserved exclusively for the use of the occupants of the house, to the rear of the house to less than 25 square metres.

6. (a) Any window proposed at ground level in any such extension shall not be less than 1 metre from the boundary it faces.

(b) Any window proposed above ground level in any such extension shall not be less than 11 metres from the boundary it faces.

(c) Where the house is detached and the floor area of the extension above ground level exceeds 12 square metres, any window proposed at above ground level shall not be less than 11 metres from the boundary it faces.

7. The roof of any extension shall not be used as a balcony or roof garden._


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