Technical Information about Loft Conversions


A Charles Grosvenor conversion incorporates within its design a ‘suspended floor’. This means that NONE of the new load is supported by the existing ceilings; instead such new beams are located onto proven ‘loadbearing’ areas only – so eliminating vibration and cracked ceilings. We use only the finest timber joists and Tongue & Groove floor grade chipboards. The structural design of the floor, which incorporates large timber or steel beams, is always carried out by a qualified Engineer.


To give an insulation greater than an 11in.cavity wall, we build with a 4x2in. timber framing insulated with the latest ACTIS TRI-ISO Super 9 Foil to meet the requirements of the Local Authority. The wall also incorporates a Polythene moisture barrier.


To avoid potential condensation problems, sloping walls are constructed as above, but with the addition of 2in. timber ‘spacers’ to provide ample air circulation.


1/2in. plasterboard, plus skim, fixed to timber joists (which vary in size depending on spans and load) with insulation described above, and Polythene moisture barrier. Minimum 2in. air-circulation above fibreglass. Insulation standards are the same as for walls with high heat retaining properties.


A “Dormer window” has the benefit of removing a large area of sloping roof and generally improving the ‘headroom’ or overall height within the conversion. Dormers, unless built to the highest standards however, can be cause for concern in inclement weather. A Charles Grosvenor Dormer window however, incorporates the best elements of traditional building methods with the advantage of some newer materials. Our outside protection is achieved with 3 layers of bituminous felt, hot bonded to 3/4in. plywood decking. The Dormer front and sides are finished with vertical tile cladding. We use a ‘compatible’ type and colour concrete tile fixed to treated tile battens with the additional protection of untearable roofing felt. Strength is achieved by using 4in.x 2in. and 4in.x 2in. depending on spans involved. At the junction between the Dormer and existing roof, lead flashing and soakers are used.


Recent changes in Building Regulations make use of roof-lights a more common practise that it was. They provide all the light and ventilation required without altering, to any great extent, the outside appearance of the property. They can also be the ‘alternative means of escape’ helping to meet the relevant fire regulations.


Charles Grosvenor has no fixed specification for window frames, but rather encourage our clients to choose from conventional timber frames, or UPVC double-glazed as preferred. You may be intending to change all your existing windows in time, so choose the type that suits your final scheme.


As major manufacturers of purpose made staircases you have the choice of conventional softwood stairs ready for painting and carpeting. We particularly pride ourselves on our skill in making and fitting stairs over your existing stairs and achieve that feeling of continuity.


This may include the re-positioning of existing tanks, through to the full installation of a complete bath or shower-room, or even a sauna if desired. Radiators can be fitted if the existing system will allow.


Two-way stair light circuit plus ceiling or wall lights. Twin points positioned where desired.


All walls and partitions are plasterskim finished. Softwood skirtings and architraves are fitted. No painting or decorating is carried out by the Company. Doors are unprimed ply finish. Access panels are of the hardboard type.


These apply to houses above 2 storeys when converted and will be quoted as determined by Current Building Regulations.


The plans will be prepared and submitted for approval under Current Building Regulations. Also Town and Country Planning where required. All work will be carried out in accordance with these Regulations and the Local Authority Building Inspector shall be the sole judge in this regard.

An individual and detailed Specification is shown on all final plans

attic conversion