This is a blog post aiming to help those who can’t decide on an extension type, are confused about the different types planning and what is allowed, looking at budgets and specification.
Planning permission is still a widely misunderstood concept, we sometimes feel like we are in the dark. Laws can and will change which in turn can take advantage of homeowners or members of the public looking to add an extension, do some remodelling or create a new dwelling within the boundaries of our land.
The different types of planning are as follows:
- Householder Planning Application
- Full Planning Application
- Outline planning consent
- Reserved Matters
- Listed building consent
- Advertisement consent
- Lawful Development Certificate (LDC)
- Prior notification
Typical Types of Extensions
The most frequent one we see is for an existing property in need of extra space, wanting to either develop to the rear (a single storey or even double storey rear extension), or to the side.
A frequent form of extension which allows the homeowners to add lots of vital ground floor space is a single storey ‘wraparound’ extension, which combines the rear extension with the side extension to create a large ground floor open space.
The double storey rear or side can add space upstairs also, with the addition to an extra ‘wing’ at the side of the house, generally located at the top of stairs an extra bedroom or 2 can be achieved through careful planning and layout.
Loft conversions which can include dormer windows (flat roof and gabled), usually to the rear as planning prefers this, and can create a 3rd floor in the dwelling to add a large master bedroom with en-suite, along with extra storage space in the eaves where headroom is lower. This can be overcome with adding a dormer window, to the rear of the property, to allow extra headroom, light and space, as well as lots of value on to the property, it is a good idea that this is carefully planned. Velux windows can be added to add light and don’t require planning permission and are therefore classed as permitted development.
There are certain restrictions on some developments, if the house lies in a conservation area, is a world heritage site, a site of specific interest or a listed building (will need listed building consent), and at all time boundaries need to be respected. Any development more than 3m in length, will need to be 3m from the boundary also (known as the 45-degree rule), whereby rights of light for the neighbour will be respected, as well as privacy issues, therefore most windows/opening tend to be on the rear rather than facing the side.
Dormers tend to be on the rear, any development to the front facing the road must be subservient to the main house (can be slightly set back – and depends on the neighbours), and height of single storey can be maximum 4m of original eaves height. Two-storey extensions no closer than seven metres to rear boundary.
“No more than half the area of land around the “original house”* would be covered by additions or other buildings”. However, this can be important as if houses were built with detached garages, outbuildings etc in a good plot of land, this can be used as original area, therefore we can gain 30% (argued as permitted development potential) plus another 30% through either permitted development and then the 50% as planning permission. If the house was already extended after 1948 then this would be part of the 30% area allowed under permitted development.
According to the Planning Portal “The increased size limits for single-storey rear extensions that were previously time limited and due to expire on 30 May 2019 have now been made permanent by government.”
Class A – Extensions (enlargement, improvement or alteration)
This means for both planning and permitted development, the size of extensions has been increased (doubled), 6m for semi detached and terraces houses, 8m for detached. Therefore, a single storey space can be added to the ground floor, offering a great open plan space with glazed openings to the garden (if rear garden space permits), with a maximum 3m second storey addition to form an extra bedroom or 2.
Class B – Additions to the roof
This allows for rear dormers and hip-to-gable extensions if the additional volume created does not exceed 50m3 (40m3 for semis and terraced homes).
Class C – Other alterations to the roof
Class D – Porches
Class E – Buildings etc. (outbuildings)
This allows for an outbuilding to be erected within a residential curtilage if it is sited behind the principal (often the front) elevation, does not cover more than 50% of the curtilage and is not more than 3m in height (4m for a dual-pitched roof; 2.5m where within 2m of a boundary).
If the 6m or 8m single storey rear extension is to be agreed, a certificate of lawful development via prior notification (to the authority and neighbours) is submitted, if there are no objections by either then the certificate can be awarded, and work can commence.
Agricultural Land/Change of Use
Another large potential is that agricultural buildings may be converted to residential (up to 450m²), if the building is structurally capable of being converted without requiring engineering work and providing access can be achieved. Up to five dwellings may be created up to a maximum floorspace of 465m², of which three may be ‘large’ (>100m²), and 2 smaller i.e. 80m². This change of use is subject to prior approval being sought in respect of transport, access, noise assessments, ecology reports, flood risk, may be required by the authority depending on sites and plans for that given site.
Typical costs for a single storey rear extension are around £1,500pm2, (ranging from £1,000-£2000), or greater if a high spec kitchen/furnishing are desired. A typical 3x5m extension would cost around £20,000-£30,000. If you want a double storey it would rise to around £50k, around the same as a single storey wraparound extension. Larger width rear extensions, large wraparounds, or double storey side extensions with rear single storey rear can be from £60, 80, 100k +, depending on spec, bifold doors, kitchen layout/cost, what ground works are needed as foundations/structure may need to be improved/built to take the weight of the new extension.
Architects fees can be anywhere from 2 or 3, 5-10% of the build cost depending on level of service desired, to get through design options, planning, building regulations, working drawings (inc electrical/M&E layouts) and project management. A typical £40-60k extension may cost £2-4k in fees depending on option chosen.
We have explored the different types of planning available in each circumstance. Each development is individual to the property, the occupiers, the LPA, us as Architects to help you maximise your planning potential right for that property and individual preferences.
If you would like a quote, please email or get in contact and we can do a free initial meeting to explore these opportunities at reasonable fees.