An extension in Slough is judged against a specific document with specific numbers in it. Depth, height, roof form, the gap to a side boundary and the garden you have to keep are all written down. Slough Borough Council adopted its Residential Extensions Guidelines Supplementary Planning Document in January 2010, and it remains the document your design is judged against. We appoint the structural engineer, build to the calculations, and coordinate the building control application and inspections. Here are the numbers, before you commission drawings.
The depths Slough works to at the back of a house
Slough's guideline maximum depth for a single storey rear extension is 3.65 metres for a terraced house and 4.25 metres for a semi-detached or detached house, measured from the rear main wall of the original house. For a two storey rear extension the guideline is 3.3 metres, with deeper allowed only where site circumstances permit, such as a detached house on a larger plot well separated from neighbours.
Height is written down as well. Where a single storey rear extension abuts a residential boundary, the guideline maximum is 3 metres for a flat roof, and 3 metres at the mid-point of the pitch at the side boundary for a pitched roof. All of it sits in the Residential Extensions Guidelines Supplementary Planning Document, adopted in January 2010.
First floor and two storey work, at the back and at the side
Slough Borough Council states that in general there is no potential for a first floor or two storey rear extension on a mid-terraced property. Its reasons are the adverse impact on adjacent properties, and that such extensions are generally out of keeping with the pattern of development. Where one is possible, Slough requires a pitched roof tied into the main roof of the house, and states that flat roofs will not be acceptable at that level.
Two further rules apply at that level. The council applies a 45 degree code on the horizontal plane, measured from the closest edge of the nearest first floor habitable window of the neighbouring property. It also expects a two storey or first floor side extension to be set off the side boundary by at least one metre, ideally at both ground and first floor level, to keep a visual gap between houses.
The garden you have to keep behind it
Slough will not permit a rear extension unless the usable retained rear garden keeps a minimum depth. That is 7 metres for a one bedroom house, 9 metres for a two or three bedroom house, and 15 metres for a house of four bedrooms or more. Where an irregular boundary means that depth cannot be reached, the council may relax the standard if the retained garden exceeds 40, 50 or 100 square metres on those same bedroom bands.
The reason is drainage as well as amenity. The council states that its minimum garden depths are set so that soakaways can be built for the correct disposal of surface water from approved extensions. It states that a soakaway needs to sit at least 5 metres from the completed extension. Measure the garden before you fix the depth, because the retained garden is what limits the extension rather than the other way round.
Permitted development in Slough, and how to be certain
The only Article 4 direction Slough Borough Council publishes covers the stationing of caravans and moveable structures, and it applies to the whole borough. It does not remove permitted development rights for house extensions. So no Article 4 direction in the borough withdraws those rights from your house.
If you want certainty rather than a view, Slough Borough Council offers a Lawful Development Certificate where you want to be sure that your proposal is permitted development. It gives you the position in writing, which is worth having when the house is sold. We build to whichever route you take, and we tell you at survey which one your scheme is heading for.
- Building control inspections at foundation, damp course and steel stages
- Levels, drainage and landscaping made good around the new build
- First fix and second fix plumbing and electrics throughout
- Single and double storey extensions
- Roof works and structural alterations at roof level
The GS Renovation Difference in Slough
Extensions in Slough succeed or fail at design stage, and the numbers are published. We take the depth, the height, the side boundary gap and the retained garden off your plot at survey, then set the design against the 2010 Residential Extensions Guidelines before drawings are commissioned. We appoint and coordinate the structural engineer, build to their calculations, and coordinate the building control application and inspections with Slough Borough Council. That is one point of contact from the first survey through to the final inspection. GS Renovation Ltd is fully insured and registered in England, company number 14611254, and rated 4.9 from 31 reviews on MyBuilder. Quotations are free and carry no obligation.
- A written scope and programme agreed before work starts
- Dust screens and floor protection in occupied homes
- Founder-led team with 30+ years of hands-on experience
- Scaffolding and site set-up planned for tight London plots
- Foundation depth set after trial holes, drains and trees are checked
- Building control inspected at foundation, damp course and steel stages