Raising height of Pitched Garage Roof

24 Oct 2010
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United Kingdom
Our semi has a lean-to garage at the side, rebuilt in 1988 under a building notice (the original was falling down). It is single brick/block with a concrete tiled pitched roof sloping at ~20° (should be > 22.5° for the tile spec but works just fine). However the ceiling of the garage is rather low (< 2m) because the height of the pitched roof was limited by the position of a stairway window on the house wall. Basically the builders squeezed the best sloping roof into the space available given that we definitely didn't want a flat roof.

We are thinking about moving the house window (to the top rather than the middle of the stairs, as it is in several houses in our road), and then we could have a higher pitched roof on the garage (and a more standard door size etc.). We envisage adding say a couple of layers of concrete blocks to the garage wall and reconstructing the pitched roof that much higher (with a proper 22.5° slope).

1. I believe that we do not need planning permission for this (providing the resulting pitched roof is no higher than 4m). Is that correct?

2. Can you tell me which parts of the building regs would apply to this project (I assume as an outbuilding I don't have to worry about insulation etc., just structure, but what about moving the house window?).

3. Would I need to submit plans to building control or would a building notice suffice?

The garage has substantial foundations, BC insisted on that in 1988 just in case we wanted an extension on top one day (something that local planning will no longer allow because of the "terracing effect"). But how high can a single skin wall be taken? That is my biggest doubt really, what the regs say about single skin walls. It has thicker "pillars" every so often, so is it OK to add some courses?

Or is moving a window the "no, no"? It is the last original one with coloured lead lights (so obscured) but opens, well would if we unjammed it. I know PP is needed for new windows to the side unless they are obscured and opening only above 1.7m, but can I just move a new version of what I have 0.8m up and 1m along?
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