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Stunning Loft Conversions throughout Lancashire & Manchester.

Welcome to Rafter Loft Conversions, so you are considering a loft conversion. Congratulations, you’ve made a fantastic decision! Rafter Loft Conversions aim is to provide all our clients new and old with a loft conversion package that represents excellent value for money.  If you are looking for a loft conversion company in Lancashire or Manchester look no further, Rafter-Lofts offer a totally free no obligation quote and design of your loft conversion. We guarantee we will not be beaten on price for a like for like quote.

What is the process for a loft conversion?

From your initial contact we will arrange a convenient time to suit you to visit your home and discuss your requirements, each loft conversion is designed to your own individual specification to gain maximum comfortable & versatile living.

Following our visit, we will prepare you a written and fixed price proposal on your loft conversion, then if Rafter Loft Conversions are your perfect partners a time & date will be arranged for our architect to visit your home and undertake a structural survey in order to prepare your plans for approval. After you have approved the plans we will submit them to building control along with structural calculations to get full approval.

On the mutual convenient date to start work, the bulk of the material’s will be delivered on the first morning, if we require a crane to lift steels into place we usually ask for it to turn up around 10am this generally allows your neighbours to do school runs or get off to work, as to minimize the disturbance. Once the steels and primary beams are in place the construction of the floor can commence, whilst at this stage your floor to floor is determined and your bespoke staircase will be ordered.

The next stage is to upgrade your roof structure and fit your roof windows, Rafter Loft Conversions only install the top of the range Velux white polyurethane roof windows, following the installation of the windows the insulation is then introduced to make the new room conform with the latest stringent building regulations. At this point will ask the plumber / electrician to visit to fit any pipes or wires if necessary. Now that your room is fully insulated we are ready to plaster board the shell.

Now we’re ready to build the new internal walls and divide the loft into comfortable sized rooms you require, once completed the stairwell aperture will be carefully cut out, then your bespoke staircase will then be fitted. After installing the staircase there is a few of days to finish the joinery work ready for the plasterers. Our time served plaster’s will commence work when all joinery has been completed, and at this stage the plumber will commence work to attach radiators & sanitary ware, whilst the electrician does his second fix of electrics.

In just a few days after the plaster has dried, all’s left do is for you to choose the colour finish. Importantly you do not have to move out while your loft conversion is being constructed as we keep all the building work and disturbance to an absolute minimum.

A typical loft conversion takes around four to five weeks from start to finish.

Building Regulations – Planning Permission?

Building Regulations is compulsory on every loft conversion. Building Control approval of your project will not only ensure that your loft conversion is built structurally safe, but meets stringent and rigorous requirements, when a property exceeds two floors there are more requirements to be met, for example structural stability, thermal insulation, the stairwell on all floor levels should be enclosed and the stairway should open directly to a final exit, grades of structural integrity materials etc.

Well the good news is that most loft conversions now do not require planning permission, the reason for this is permitted development rights was set in Parliament not by the local authorities, therefore you are able to undertake certain types of modification to your home, under what is classed as your “permitted development rights”, which is 40mon terrace houses, and50m3 on semi and detached houses.

Permitted development rights are restricted in areas of outstanding natural beauty, conservation areas and on any listed building, any particular alteration to a building described will always require planning permission for any alteration. Any work to a listed building, even if it does not alter the appearance will require listed building consent.

Compliance to Building Control guarantees you a certification of the works upon completion, this is an important document for and when you to process the sale of your home in the future.

Here you can have a look at some ridiculous permitted development loopholes.

What is the cost for a loft conversion?

The four most popular Loft Conversions.

Cost of a Velux Loft Conversion

The simplest of loft conversion are Velux loft conversions, these particular conversions start from £18,000 upwards depending on the complexity, this is when your loft conversion if formed within the existing roof space without actually altering the profile of your roof, the conversion works best when you have ample headroom so you can make full use of all the space available.

Cost of a Hip to Gable or Hip End Dormer

The cost of a Hip to Gable & Hip End Loft Conversion generally start from £25,000 and are for properties with a slopping side roof, which means that the side of your roof slopes inwards towards the ridge/chimney. A hip-to-gable style conversion would change the shape of the roof by extending the existing the ridge and giving you a much larger loft area. Generally houses with hip roofs do not tend to not have enough internal volume over their existing stairs, so a Hip to Gable conversion is constructed to carry your new staircase.

Cost of Rear Dormer Loft Conversion

Flat roof dormers prices start at £28,000, Rear Dormers are popular as they create maximum floor area and also give natural light through windows or French doors. Depending on circumstance, planning permission is not always required as the conversion can be carried out with permitted development rights and also meets certain criteria. Fitted with Firestone EDPM Membrane.

Cost of a Hip to Gable with Rear Dormer (Wrap around)

Wrap around dormers is when both a Hip to Gable and a Rear Dormer are introduced maximising the full potential floor area, Wrap around dormers generally start at £35,000. The Wrap Around loft conversion is suitable mainly for semi-detached properties.

How long does a Loft Conversions take?

A Velux loft conversion is by far the quickest loft conversion to complete, this particular type of conversion is generally built and finished in 3 weeks, allow an extra week if a en-suite/bathroom is to be incorporated in the loft conversion.

Hip to gable loft conversions are typically built in 4 weeks, however this depends on your existing roof cover, i.e. slate and plain tiles usually puts a few extra days of labour due to complexity, again if a en-suite/bathroom is introduced allow an extra week.

A rear dormer loft conversions take around the same time as a hip to gable loft conversion, again the same applies to the en-suite/bathroom.

The wrap around dormer is the longest to construct, this takes around 6 weeks, dependant on which existing roof cover you have, the same applies if a en-suite/bathroom is introduced on the build.


Loft Conversions to complying with building regulations!

 Structural Stability

New structural members or alterations to existing structural members in order to convert an existing roof must be undertaken by a structural engineer, this is to ensure both the stability of the existing structure and the structural sufficiency of the new structure, formal calculations may be requested by Building Control in support of an application for approval.

 Means of Escape

A house that is extended or altered to add a third storey has to comply with stringent emergency escape provisions. The conversion of a roof space that provides one or more new habitable rooms at second floor level should include the following provisions:

  1. The existing stairway/stairwell at ground and first floor levels should be enclosed and the stairway should open directly to a final exit, or to a space which provides two escape routes, each to a final exit, and separated from each other.
  2. The new stairway must comply with the requirements of the regulations. A new staircase within an existing stairway enclosure should be separated from any new rooms, and should be separated from that room and the rest of the house by fire resisting construction.
  3. Escape routes over balconies or flat roofs (of fire resisting construction) will require to be protected by guardrails in accordance with the Regulations.
  4. The installation of hard wired and battery back-up smoke alarms in all habitable rooms off the escape route is mandatory, unless you have an open plan staircase then a sprinkler system may be introduced.  

Fire Resistance

All loft conversions must conform with fire requirements in the National Regulations. This largely concerns the conversion of an upper floor ceiling to a new floor construction, which must then achieve the fire resistance of an intermediate floor – normally 30 minutes.

The requirement for fire resistance includes any member supporting a floor, even if this extends beyond the actual floor area of the accommodation, I.e. between the outer wall of an loft space and the external wall at the eaves. (Note, if the roof accommodation will be of a different occupancy, such as a separate flat, to that on the floor below, it may be necessary to achieve full separating floor fire resistance, usually 60 minutes.)

If an existing floor supports a new staircase to habitable space in the roof, If an attic wall forms part of a separating wall, between properties, it must achieve the full fire resistance of a separating wall.

If the roof space incorporates a chimney or a flue any new construction must comply with the space separation requirements for combustible material. No combustible material other than a floor, skirting, picture rail, mantle-shelf or architrave should be closer than 200mm to a flue in a chimney or 40mm from outer surface of a masonry chimney. Nails, screws or other metal fixing timber to a masonry chimney should be at least 50mm from the flue always remember to consider the position of the chimneys and ventilation stacks in relation to the position of windows.

Surface spread of flame

Walls and ceilings to any new accommodation within the roof must comply with appropriate spread of flame requirements. Plasterboard will meet the spread of flame requirements. Any surface that slopes at an angle of 70 degrees or more to the horizontal is deemed to be a wall.

Sound Insulation

All walls separating dwellings must have adequate airborne sound insulation. Existing separating walls in roof spaces may not provide adequate resistance to airborne sound if the roof is converted into occupied space on one side of the separating wall. If an attic room abuts a separating wall, the wall must therefore be lined to provide equivalent sound insulation to the separating wall elsewhere in the building.

Gaps left in existing separating /party walls should be filled with bricks or blocks with a sand and cement mix. If a timber frame is used it should only be fixed to the floor and roof structure, any gaps between the framing and the floors and roofs sealed with acoustic sealant. Separate timber frames will reduce the roof space dimension between separating walls by approximately 90mm.

Plasterboard lining to a timber framed separating wall will normally be adequate for fire resistance but additional plasterboard may be required to improve sound insulation. Mineral fibre/plasterboard laminates can be used to line timber frame and masonry separating walls to improve both sound insulation and fire resistance.

In residential dwelling houses if a loft conversion is going to be constructed, construction should be designed in such a way that it provides reasonable resistance to sound from other parts of the same building and from adjoining neighbours.

Ventilation of Rooms

Windows to habitable rooms should be proportional to the floor area with background ventilation as required in all rooms. Bathrooms should be provided with an opening window, and a mechanical ventilation fan should also be provided which may be operated intermittently. 

Ventilation of Roof Space

The introduction of a room into a previously open roof space will restrict the flow of natural ventilation through the roof intended to avoid condensation. The existing ventilation provision, if any, at the eaves may have to be increased to maintain a continuous airflow, a 50mm gap should be maintained on a flat roof dormer to provide a lateral flow of air.


The pitch of any stair leading to a room within the loft must confirm with Building Requirements, they must also conform to requirements of escape, and require some form of fire protection.

Adding a loft conversion to a two storey building effectively increases it to three storeys with consequent increased requirements, there is no restriction on the type of staircase, which may be a straight flight, a winding staircase, a quarter landing or a half landing. Loft ladders are NOT to be used to provide access to any new room in the roof other than for storage.

In instances where there is insufficient headroom at the top of a staircase a Velux roof window can provide additional height as well as light and ventilation. An alternative means of achieving the required head height is to create a dropped landing. This also creates an interesting design feature.

Thermal Insulation

Any habitable accommodation inserted into the roof space will be above this insulation and has to be insulated in line with the requirements of the current National Regulations. This can be done by either insulating the whole roof pitch from ridge to eaves, or by insulation around the new accommodation only.

The first method is more complicated to do, and will involve more insulation material, particularly in the apex of the roof.

The second method saves on the amount of insulation required, the walls and any part of the sloping ceiling and any horizontal ceiling over the habitable space will in this case need to be insulated.

Any gable wall in the roof accommodation will have to be insulated to conform with thermal requirements for external walls. This can be done by using plasterboard with insulation laminated to the back face or in timber-frame construction by inserting mineral wool insulation between the studs before lining them with a vapour control layer and plasterboard.

Daylight and View Out

Regulations state there is a specific requirement that glazed areas must be equivalent to a proportion of the floor, any habitable room should have a source of daylight and a view out. Good practice would suggest a minimum glazed area equivalent to 1/10 of the floor area for this purpose.

Roof windows can provide these facilities and dormer windows general appearance of a roof should not be affected by the conversion of the roof space, even if the height and shape have not been affected.

If a roof overlooks a ‘public highway’, or any projection above an existing roof plane it will require planning approval. Roof windows parallel to the slope of roof do not require planning approval as they do not project significantly and will therefore have a limited effect on the appearance of the roof. In a particularly critical environment, such as a conservation area, a recessed type of roof window can be used instead of a standard type.


Where a new bathroom is located in a loft conversion, provisions are required for hot and cold water supplies and drainage. Access must be made available to for maintenance to any water tanks re-located into the void areas.

If pipe-runs from the hot water cylinder are long, and the appliances will only have occasional use, for example a visitors bathroom, the use of electric instantaneous water heaters to basins and showers might be considered as an alternative.


If you choose to have a bathroom in your loft conversion the position of the existing drainage will influence the location of sanitary fittings in that there is a maximum permitted length for unvented branch connections from baths and basins. If the lengths of branch pipes exceed these requirements they must be directly ventilated to the external air.

Alternatively, a ventilating pipe may terminate inside the building if fitted with an air admittance valve, a AAV installed internally are usually fitted within rooms or in the roof space, the great advantage of using a AAV is that they remove the need for holes through the roof or external walls, and reduce the amount of pipework required.


Loft conversions usually have low heat losses due to the high elemental insulation requirements required, as long as the existing boiler has sufficient capacity there should be no problem adding additional radiators. If the conversion forms part of a larger refurbishment, then a new central heating system may be viable.

General Requirements

Any re-roofing necessary in converting the roof must conform with the performance of the original roof in terms of fire resistance, durability and general fitness for purpose. Preservative treatment to roof timbers is not mandatory, but if evidence of previous infestation of woodworm or previous fungal decay is visible treatment should be undertaken prior to sealing the roof structure.

Floor Joists

Your existing ceiling joists are very unlikely to be adequate to act as floor joists.

Fit new deeper joists between existing ceiling joists, if existing binders are to be removed the existing ceiling joists will require support from the new floor joists and their weight should be added to the floor joist dead load. Position new steel beams above existing ceiling. Insert new floor joists into beam web.

New partition loads in the roof space should not be supported by the floor decking only, additional joists will be required below internal non-load-bearing partitions running parallel with the floor joists.

Floor openings formed for stair access can impose heavy loads on trimmers. Trimming joists onto existing load-bearing walls, or onto new walls or floor beams either transfers these concentrated loads. Double joists may be required as trimmers to frame stair openings.

Floor Beams

Beams to support floor joists can be of timber or steel. Depending on the structural integrity, generally timber based beams are doubled or trebled up to conform to stress grades.

The structural design of timber beams will need to be undertaken for each case individually. Loads on beams should be assessed and beams designed in accordance with standard engineering principles.

Exposed beams supporting floors must provide 30 minutes fire resistance. This can be achieved by oversizing timber beams, timber burns at a known ‘charring rate’ of 20mm per half hour.

It is recommended that any steel beam leaves a minimum headroom of 2.0m, which is the mandatory minimum height for landings and stairways. When steel beams are used and timber joists are fitted between, it is important to allow for the shrinkage, which will occur, when the joists dry to their equilibrium moisture content.

The floor deck or ceiling should not bear on the steel beam and cause distortion of the floor or ceiling. A movement gap of approximately 12mm between the steel and the floor deck and 5mm between the steel and ceiling will generally be adequate for moisture movement.

If new floor joists are to be installed over an existing ceiling it is advisable to allow 10mm clearance between the underside of the joist and the ceiling to allow for possible deflection of the joists under floor loading.

Floor Decking

Floorboards should be cramped before screwing, and all screws should be below the board surface, screws should be 55mm in length 3.5mm in width. Three screws should be used at each support. The ends of boards should be butted over joists with both boards adequately supported. End joists should be staggered so that they are at least two board widths apart. Any board should span at least three joists.

Flooring to habitable roof space should be laid in accordance to reduce vibration and damage to existing plaster ceilings to be retained, fixing floor decking to any floors by screwing is preferably to nailing.

Loft floor decking is usually fitted to a house that already has heating therefore moisture content isn’t really a issue and this prevents excessive shrinkage and possible distortion, tongued and grooved flooring is usually used in loft conversions 2400mm x 600mm

Roof Beams

When purlins and supports are to be removed to form usable space, alternative support must be provided to the rafters. It is important to establish the total function of the existing purlin since in some cases purlins and ties may provide resistance to outward thrust as well as vertical support.

A number of alternative solutions are possible depending upon the size and construction of the roof, such as the following (either individually or in combination)

  1. If existing purlin support has to be removed alternative support off existing load-bearing walls below or onto a new supporting structure in the roof space is required.
  2. Insert new purlins at new levels, this may necessitate additional rafter support because of the longer rafter span between the new purlin and the eaves. This can be provided by an additional purlin or by stiffening the rafters with new timber alongside the existing.
  3. Insert a ridge beam, the simplest way of installing a ridge beam is to go from gable/party to gable/party walls. Inserting a ridge beam should be considered when it is necessary to remove existing ceiling joists. Adding a ridge beam minimises outward thrust in the rafters.
  4. It is uneconomic to use solid timber purlins for unsupported spans in excess of 4.0m. Internal load bearing walls or posts should be used where the span exceeds 4.0m. For longer spans, or where no intermediate support is possible, fabricated timber or steel beams should be considered
  5. Deep beams may be used to support both roof and floor load, using either metal hangers nailed to the primary beams to carry the floor joists.

Alternative timber beams include:

  • Plywood web I-beam
  • Plywood box-beam
  • Steel flitch beam

Beam Supports

Beams can be built into existing cavity walls but to allow for end supports the beams must be approximately min 200mm longer than the clear span of the room or space. Timber beams should not be built into external solid masonry walls. Heavy duty galvanised steel hangers are an alternative means of supporting timber beams. Steel hangers should be appropriate for the load to be supported. Hangers should be supported directly by bricks or concrete blocks with the face of the hanger tight against the wall face.

Only timber posts or studs must support timber beams in timber frame walls. This may require walls to be opened up to insert new timbers. Alternatively it may be possible to position the post against the wall face, f it is necessary to insert new studs on posts into an external timber frame wall, the vapour control layer must be reinstated and the effect on the thermal insulation of the wall considered.


If new rafters are to be inserted between existing ones or alongside, they should be selected from span tables set out by building control, if purlins are repositioned, it is essential to check the effective rafter span, the overall rafter length required should be checked against the availability of suitable timber and provision for lapped or spliced joints made when necessary. 

Calculation of Roof Loads

The roof imposed load and dead load from roof tiles or slates, timber battens, underlay or boards, rafters, insulation and linings is measured on the slope, the total weight is resolved to produce a vertical load on plan.

Roof Windows

The specification of the windows is particularly important in loft conversions, not only are they crucial in providing in providing sufficient ventilation suitable for installation. Both centre-pivot and top-hung windows can be rotated to provide access for cleaning. Repainting of the pre-finished external aluminium cladding is not necessary.

Incorporating a roof window will usually reduce the total roof load since the weight of the window may be less than that of the roofing materials, which it replaces. The imposed load on the roof is unaffected. Narrow roof windows can be fitted between rafters of 600mm spacing, otherwise trimmed openings will be formed to fit the required size of window.

Start to Finish!

Rafter Loft Conversions provide a comprehensive all in one loft conversion service, from your initial free quote & Cad design, submitting the relevant paper work to building control and planning (if required) and overseeing every step of the build dealing with building control through to the completion.  Rafter Loft Conversions are passionate about what we do and understand getting a loft conversion can be a major disruption. All loft conversions are project managed from start to finish to ensure the process of your loft conversion runs as smoothly as possible, with minimum disruption.

Working with us

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