design process

Single Storey Rear Extension CASE STUDY

  • Islington
  • Ground floor single storey rear extension
  • Project duration - 14 weeks


  • Building a 3m permitted development single storey rear extension to old Victorian town house
  • Internal refurbishment maintaining original features of the property
  • Large bi fold doors to rear with addition of 2 no skylights
  • New kitchen located in extension
single storey rear extension


  • Set up secure hoarding for site access and protection
  • Set up of plant and delivery of initial materials
  • Isolation of services on site for safety
single storey extension


  • Digging the foundations with depths dependent on-site conditions
  • Building Control to visit the site and approve the foundations
  • Pipework, drainage and services will then be laid within the foundations
  • Concrete footing will be poured in and levelled
  • Bricklayers to build up the damp-proofing course
  • Building Control will need to visit again to approve the damp proof course
rear extension


  • Drains will be installed and trenches dug for the pipework
  • Concrete lintels will be inserted into the brickwork, if required
  • Steels will be put in place, along with pad stones that have been approved by Building Control
  • Sand will then be laid before damp-proofing membrane is put down
  • Insulation will be fitted
  • The concrete slab for flooring will be poured


  • The external cavity walls will start to be built from blockwork and brickwork
  • Cavity wall insulation will be fitted
  • Wall ties will be inserted to fix the new walls to the existing ones
  • Lintels for windows and doors will be fitted
  • At this stage the external windows and doors will need to be templated
single extension


  • The roof structure will be created as per the design and structural engineers’ specification.
  • If you’re having rooflights, these openings will be created
  • Roofing membrane will be laid over the new rafters
  • Tiles/slates will be laid or fibre glass depending on flat or pitched roof construction
  • Fascias, soffits, verges and guttering will be fitted
  • The concrete slab for flooring will be poured
internal wall


  • Internal walls will be built and plasterboard applied to the inside face of the new walls
  • First-fix carpentry, plumbing and electrics will be completed


  • The bi fold/ sliding doors will be fitted along with any roof windows creating a water tight extension.


  • Plastering will take place and must then be left around a week before decorating can be carried out
  • Once the plaster is dry the first couple coats of paint can be applied


  • Second-fix electrics will be carried out, which means sockets will be made live, switches will be put in place and lights fitted
  • Flooring will be fitted along with skirting boards
  • Second-fix plumbing means taps will be installed and connections completed
  • Kitchen units will be installed
external work


  • Once the bulk of the building materials are cleared from site works such as fencing can take place
  • Gardens walls can be created for flower beds
  • Decking/ tiles can be laid to create an external patio area