Semi underground outbuilding

Updated on 5th March 2018 in Permitted Development
0 on 5th March 2018

Hi all,

I am after some advice regarding a potential project I am considering.

I own own a semi terraced house (the north of the property is completely conenected to next door, the south of the property is setback about halfway so their rear half of the house is connected to the front half of ours).

The property was built circa 1960 with a brick built shed roughly 2.1m x2.4m in the garden.

The previous owner has connected this shed to the property by means of a utility corridor roughly 1.2m deep (and the width of the shed) and added a conservatory adjacent to it. The conservatory is circa 3.5m x 2.1m.

The shed, utility corridor and conservatory make up about 41% of the sqm of the original house.

I am am proposing to dig out some of the garden and build a second “shed” – used as a games room for the kids (and me).

From my understanding it can be done under permitted development providing that:
1. It is not higher than 2.5m
2. THe total outbuildings do not occupy more than 50% of the land

My questions are:
1. if I dug the garden down, say 2m, could I still have a 2.5m wall in the garden or is the max height of 2.5m internal?

2. Does the land include the front garden or just the rear. To get the size I want, assuming I have to consider the space used by the conservatory, existino shed and utility corridor, I would be just over at 52%. If the front garden is included then I am within the limit

3. How can I find out if utilities are under the rear garden?

4. Is there a limit as to how deep I can dig a hole in my rear garden. For example, could I dig the hole 4m deep and bury my new room beneath the garden? (Hypothetical at this stage – I appreciate there are many complications with this)

Thanks in advance for your help


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