Garage conversion and raising roof - Permitted Development?

[Gooman]

We've bought a three-bed detached house that has a double-length single-storey flat roof garage attached to one side (see existing layout below)

 

We want to partition the garage into two and convert the far end (rear garden end) of the garage, knocking out the utility walls and from the garage into the kitchen to create a large open plan kitchen/diner.

 

As the floor is about 100mm lower than house level, we need to raise (and insulate) it. Which then means we need to raise the roof by around 150mm (to include insulation and service void). But we also want to add a roof lantern, which will take the peak over 150mm.

 

We will also need to reroute the soil pipe (just visible in the picture above) as it runs through the rear part of the garage. 

 

I'm confused as to whether this project is likely to fall under Permitted Development, or whether it's likely to need Planning Permission. I've read and re-read the info on the Planning Portal and the Technical Guidance on PD many times, and I'm still none the wiser.

 

Here's what I'd *like* to be the situation:

• Raising the roof and adding the roof lantern is classified under Class B (enlargement of a house consisting of an addition or alteration to its roof), since nothing will go higher than the existing roof ridge or beyond the line of the eaves on the main roof. Although Class B prohibits moving a soil pipe, Class G allows it.

 

Here's what I'm afraid might be the situation:

• It's Class C, and so isn't PD as the roof lantern will take it over 150mm, and Class G can't be combined with other classes for moving the soil pipe.

 

If the wisdom of this group is that it should probably classify as B and G then I'll be applying for a Lawful Development Certificate. But if it looks highly likely that I'd need full PP then I'd rather not waste the fee for that!

 

[Conor]

It's worth sending an email in to your planning department to ask for clarification. I was in similar position when building a "shed". As it's rear wall doubled as a boundary wall, the hight limit could be interpreted as 2m, rather than 2.5m as it would for a standalone shed. Their interpretation was that the higher height limit applied. They recommended that I send though as constructed drawings and they would send through a confirming compliance letter.

[Gooman]

My local planning department will only provide that sort of compliance via a Lawful Development Certificate, which has a £103 fee. If it's highly likely to need PP then that would be wasted money.

[Temp]

I believe the roof light over 150mm issue would mean planning permission is required. However...

 

Would the converted garage and roof light meet the rules for a side extension? Eg It would it be less than 4m high (3m within 2m of the boundary)? If so then you could demolish the garage and rebuild it as a side extension under permitted development. I'm not suggesting you do that but it means it would be hard for the planners to refuse permission for what you actually do want to do. 

 

If you just went ahead without planning permission I think they would be unlikely to initiate enforcement action unless there was a complaint buy a neighbour. If a neighbour was to complain the planners might feel obliged to initiate enforcement action but you could at that point submit a retrospective planning application. My guess is it would be waived through because they know you could build what you want by knocking down the garage and rebuilding it under the rules for a side extension.

 

One option would be to apply for a CLD to knock the garage down and rebuild it within the permitted development rules for a side extension. They would not be able to refuse this. Then instead of knocking it all down just do the conversation you want. The end result would match the drawings submitted with the CLD.

 

 

 

Edited November 7, 2019 by Temp

[Gooman]

I've been advised elsewhere that it should qualify as Class B, with the soil pipe relocation as Class G. Although Class B prohibits soil pipe work, since that work could be done independently it would then qualify under Class G.

 

Looks like I'm going for the Lawful Development Certificate route. Good point that we could demolish and rebuild as a side extension (it would definitely qualify for that) - I'll use that as part of the justification.