Here we explain about planning permission and the criteria applied to determine if the householder needs to make a planning application to cover their loft conversion project.
For obvious reasons the scope of permitted development in conservation areas is much more restricted than in most towns and cities.
As a general rule of thumb; if your property is located in a designated conservation area than, under the planning laws, your project will require aproval from your local planning department.
Although some, and it is only some, local authorities will allow conversions with windows which fit flush to the existing roof, there is no way that you should undertake any roofing work without consulting the council.
If your projects design includes a dormer than it is absolutely certain that planning permission will be required. We should also point out at this stage that wheather planning consent is required or not your project will have to comply with the Building Regulations.
Highway Facing Roof Slope
If your intended loft conversion includes a dormer, or any other alteration to the roof, which faces a highway than your project will require approval under the planning laws. But it is highly likely that permission will be refused.
However, should the dormer be facing the rear of the property, i.e., away from the highway, than it is usually not necessary to obtain planning approval.
Much depends on the attitude of the local authority. They frown on the large box dormers which sprung up like a plague during the 1980s (and were actually excluded from Permitted Development prior to 1990) but are relaxed when it comes to the dormer being at the rear of the house.
Side dormers though are usually a source of contention and, if you are determined to go down this route, you will need to consult the local authority as planning approval is often required in those circumstances.
At this point it should be pointed out that, with typical ambiguity, the definition of a ‘highway’ can not only include roads but also lanes and footpaths.
Building Above The Existing Roof Line
It is explicit in the regulations that if your loft conversion project features a dormer or structure which will extend above the existing roofline than a planning application will need to be made.
If your conversion will feature only flush fitting roof-lights than there isn’t an issue here but structures such as balconies or dormers will have to be considered carefully.
The first thing to do is to establish the highest point of the existing roof. This should be reasonably straight-forward as the ridge, or apex, of the roof is by definition usually the highest point.
An exception may occur if the roof has been re-tiled along its ridge, thus increasing its height, or if a parapet wall has being built.
However, the rule is very much that the apex of the roof provides its highest point and, as long as any new structures are built below that point, than approval will not be required.
It will surely come as no surprise that attempting a loft conversion in a listed building will be fraught with difficulties and strangled in red tape.
For the vast majority of us this section will have no relevance but, should you live in such a building, than your project will not only need to meet the planning and building regulations but ypu must also obtain listed building consent.
Listed building consent will apply even if the proposed
conversion is purely an internal procedure with no roof-lights. The
only good news is that a listed building consent application is free.
Increasing The Size Of The Original House
The Town and Country (General Permitted Development) Order (1995) rules that the maximum allowance for extending space within the original house is 50 cubic meters (40 cu m for terraced houses) or 10% in both cases.
The original house, or ‘dwellinghouse’ as the legislation states, is the state in which the house stood on July 1, 1948 or when it was first built. Whichever is the later date. The volume of the original house includes the roof space and any subsequent extensions.
So, if your property already has, for example, a ground floor extension, than, under the planning permission regulations, the size of that development will count towards the allowed space in addition to the space required for the loft conversion.
In other words, if your house has a kitchen extension of 20 cubic meters than only 30 cubic meters would be available for the loft conversion.
Calculating the volume of the original house is done by measuring the external dimensions and should include any extensions, porches etc.
For more info see the related pages below
Structural calculations for loft conversions are of course hugely important to ensure safety and that the proposed plans meet building regulations
What is the difference between planning permission and building regulations approval for loft conversions ?
Using And Fitting Loose Fill Insulation In Your Loft