Types and costs

single-dormer-loft

Single dormer loft is the most common loft conversion type that we do - constructed on terraced houses without two storey annex at rear (external rear wall is straight). Rear part of the roof is completely removed and new dormer structure is constructed, normally with couple of windows or a Juliette balcony and a window. Front pitched part of the roof can be re-slated / re-tiled or left as it is - depending on condition. Normally you can have one bedroom and a bathroom (en-suite or shared), but on bigger houses it is possible to create two bedrooms and a bathroom. Bathroom can be installed either partly above the new staircase (mostly under the pitched part of the ceiling) or at the rear. The former gives the most space and light in the bedroom, while size of the bathroom is compromised. The latter - bathroom is bigger and bedroom size is compromised. The bedroom doesn't have dormer windows facing the rear - only Velux windows in the pitched front roof.

Typical terraced houses in Walthamstow, Woodford, Leyton, etc. are around 7m long from front wall to rear wall internally (to wall with a window facing the side return, if there is a rear annex) and 4.2-4.5 m width (from one party wall to another internally). The single dormer loft conversion costs on the average house would be in the region of £23000 + VAT and upwards, depending on size of the house, whether bathroom installation is required or not, what state of finishing is required, etc. It takes up to 8 weeks to complete the project. Customers normally are required to supply dormer windows / doors, fittings, equipment and finishes.

double dormer loft

Double dormer loft type is also called L-shape dormer and is the most efficient loft conversion type in terms of costs and value added. It can be constructed on a terraced house with a two storey annex at rear. Rear part of the main roof is completely removed, new dormer structure is constructed. The rear annex single pitch roof is completely removed and dormer structure is added. Normally the main room would have a window or a Juliette balcony and the rear dormer would have a window. Front pitched part of the roof can be re-slated / re-tiled or left as it is - depending on condition. Normally you have few options of how the spaces can be organized:

  • one bedroom within the main space, bathroom in the rear dormer. In this case, if the rear dormer is big enough, there may be a space for bathroom and some storage or even a small study;
  • one bedroom and en-suite bathroom within the main space and another bedroom within the rear dormer;
  • one bedroom and shared bathroom within the main space and a bedroom within the rear dormer.

The choice usually depends on one's preference - either bigger bedroom space or bigger bathroom, whether bathroom is shared or not, the amount of light getting into the bedrooms, etc.

Typical terraced houses in Walthamstow, Woodford, Leyton, etc. are around 7m long from front wall to rear wall internally (to wall with a window facing the side return, if there is a rear annex) and 4.2-4.5 m width (from one party wall to another internally). The double dormer loft conversion costs on such average house would be in the region of £33000 + VAT and upwards, depending on size of the house, whether bathroom installation is required or not, what state of finishing is required, etc. Normally it takes around 10 weeks to complete the project. We feel double dormer is really the most sensible choice - for an extra £8000 - £10000 + VAT you can have two bedrooms added to the house against only one bedroom in a single dormer type project. Customers normally are required to supply dormer windows / doors, fittings, equipment and finishes.

hip to gable loft

Hip to gable loft conversion is the most extensive project: the whole roof will be fully removed and new structures constructed. In the beginning of the project house becomes exposed to the elements, so a temporary scaffolding roof is required. Once the structure is ready, external roofing works are carried out. Normally the gable part of the roof is clad in the same materials as the dormer cheeks but it can be built with bricks or blocks and rendered. There are two options on how the gable wall is constructed: a) either dormer cheek is moved away from the gable surface, thus showing the outline of the original roof or b) dormer cheek is level with the gable - no outline of the original roof is visible. In our opinion, the former (dormer constructed with a clear roof outline) looks better aesthetically while the latter gives more internal space and flexibility in planning the layout of rooms. The rest of the project details are same as in single or double dormer conversion.

Mostly this type of conversion is carried out on semi detached houses in Chingford, South Woodford, Wanstead and other areas. The houses typically are around 7 m length (measured internally, to the straight rear wall) and around 5-5.5 m width. As mentioned, the scaffolding roof is required and this raises the costs noticeably. Hip to gable single dormer conversion costs on average house would be around £40000 + VAT and upwards. Factors affecting the costs are: number of bedrooms, whether bathroom installation is required, level of finish, etc. Customers normally are required to supply dormer windows / doors, fittings, equipment and finishes.

mansard loft

Mansard loft conversion has a flat roof, with the back wall sloping inwards at an angle of 72 degrees. Windows are usually housed within small dormer boxes. So, as in a case of dormer conversion, the rear part of the pitched roof is fully removed and new structure is constructed. Normally cheeks of the mansard dormer are raised in brickwork. This kind of conversion is typically done when the front side of the roof is raised (this would always require planning permission) - so it looks less imposing from the street side. This would be the conversion done on houses with no ridge - when the original roof is so called "London roof" (street side of the roof is hidden by a parapet and slopes are constructed for water to divert into a central valley which then is sloped towards rear). Also, quite often, this is the only way to do a loft project in conservation areas - as the structure looks much less imposing and more inline with the original house design.

On the downside - the mansard loft costs are quite noticeably higher than the standard dormer lofts. It could be up to 20% higher than dormer type and even more if street facing side is raised - in that case a temporary scaffolding roof will be required. Also, if only the rear side of the roof is constructed as mansard, there will be less internal space. So this type of conversion is only carried out when required by planning authorities or money and compromise on space are of lesser importance than the external looks.

velux loft

Velux loft conversion is the simplest way of adding an extra room: existing structures remain, few Velux type windows are installed within existing roofs. However, some structural reinforcements will be required: the floor structure will need to be newly done (steel beams and joists will be installed), existing rafters will need to be reinforced to bear increased weight of windows and insulation. Therefore, although externally there isn't much work, internally works are pretty much the same as with any loft conversion. There are more cons than pros to choosing this type:

  • the space is very limited - full height walking space is only in the middle of the room;
  • bathroom installation is really not an option - unless the house is really of substantial size;
  • the staircase would take a lot of room within the existing room (most often - within the front room) - so the hallway would need to be extended into currently living space. This is because of the building regulations requirement of 2 m headroom height above the staircase and the fact that staircase needs to be at no more than 42 degrees incline;

We feel anyone should choose this type of conversion only if there are planning restrictions - no alterations to existing roof structures externally are allowed. And it's not really a cost saving option - if done properly (meeting building regulations), the Velux loft conversion costs would only be by up to 20% lower than a dormer conversion.

Note: we assumed, the building control completion certificate is required (meaning that the new space is treated as a bedroom and not just as storage). If it's not required, then obviously this could be done cheaper and in slightly different way.


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