Can I rebuild my shed as a workshop/office and stay exempt from planning?
Property Clinic: I also want to install a wood-burning stove and toilet in the shed
The actual exemption in respect of a shed is 25sq m. Photograph: iStock
I have a block-built shed (approx 35sq m in size ) at the end of my garden. It is old and crumbling with a leaky roof and unfortunately beyond repair. I want to knock the shed and build a new one within the 40sq m exempted planning guidelines. This will give me a sound storage area, workshop and the added potential of a home office.
My questions are as follows:
1. I want to stay within the planning guidelines. Currently the shed takes the full width of the garden. I want to build an L-shaped structure, with an apex slated roof to 4m height. The side walls of the shed will be 2.5m. So overall the wall height of the new shed will range from 2.5m to 4m at its highest point – is this still within the exempted guidelines?
2. Can I put some small windows high up on the side wall of the shed? This wall would be about a foot away from the boundary to my neighbour’s back garden. If this is not possible, would it be possible to include windows if I built the shed about 60cm away from the boundary with my neighbours?
3. Does the 40sq m rule apply only to the internal measurements of the new build?
4. I want to use the shed year-round and install a wood-burning stove. Can I do this?
5. If I wanted to include a toilet within the shed, what costs are involved and, again, is this within exempted development?
Unfortunately, there is a significant flaw in your understanding of the planning exemption limits, which impacts the questions you raised. There is no exemption for a 40sq m shed, store or garage, and I can only guess that you are confusing this with the 40sq m exempted extension to a dwelling house, which is subject to very detailed restrictions.
The actual exemption in respect of a shed is 25sq m – considerably less than your existing shed at 35sq m. If you were to demolish your existing shed, then you could only build a smaller shed of 25sq m, unless you decide to go down the planning application route.
Turning to your queries, height restrictions allow for no more than 4m in the case of a pitched tiled or slated roof, and 3m in any other case. So the maximum height that you can go to is 4m at the apex. The exemptions are silent in respect of windows; however, I suspect that the exemptions which apply to extensions would apply, and that is that a window shall not be less than 1m from the boundary it faces. Accordingly, windows would not be permitted in the external walls if the shed is only a foot away from the boundary, or even if you were considering moving this out to 2ft/60cm.
The 40sq m rule which applies to an extension relates to the internal measurements of the property; however, in the case of a shed/store, the applicable area – ie 25sq m – must include the overall thickness of the walls. So assuming that the walls are, say, of standard 215mm concrete block construction, the surface area of the walls comes to a little over 5sq m and thus the actual internal floor area which is permissible is only in the order of 20sq m.
Exemptions are silent on issues such as the installation of a wood-burning stove; however, they are very precise in stating that the structure shall not be used for human habitation and accordingly I would not advise the installation of a wood-burning stove in an exempted development. Furthermore, you could find yourself in a dispute with a neighbour for causing a nuisance in close proximity to the boundary.
As regards the installation of a toilet, again the exemptions are silent on this, but you might question the merits of incorporating a bathroom within an already very small structure. There are also a host of building regulation issues which would have to be complied with to include proper connections to the underground drainage network. Adequate venting to drains and indeed ventilation could be prohibitively costly.
You need to be cautious about getting caught up in the precise meaning of “exempted development” in isolation, as there are often many other factors that can have an impact on the situation. For example, if you are in an area of special or historic interest then the normal exemptions do not apply. Similarly, if you are in a development of small houses, the base planning may well already have specifically excluded the normal exemptions.
You should also consider the size of your own garden as there is an obligation to retain a minimum of 25sq m of open space within the garden and, furthermore, the 25sq m exempted development must take account of any other sheds/stores already on the site.
The purpose of the exemption is to permit the construction of certain features within the curtilage of a house of any objects, including a tent, awning, shade and greenhouse. This also includes a garage, store or shed. The idea is to avoid unnecessary expense in taking up local authority time with normal objects/stores, but is not intended to provide carte blanche exemption for more generous developments.
While this may not be what you want to hear, from the questions raised it strikes me that you will have no option but to seek planning permission if you wish to achieve your goal. Maybe consult your local building surveyor, who can help guide you through the process.
Val O’Brien is a chartered building surveyor and member of the Society of Chartered Surveyors Ireland, scsi.ie