Project overview

The following budget proposal represents a starting point from which to tighten specifications and prioritise budget spending. The budgets can be re-worked in order to balance, for example, improvements to thermal performance, function and lifestyle considerations.

Suggested overal budget, £50-60k; aspirations extend the scope beyond the proposed budget, once the specification has been explored priorities can be evaluated.

Kitchen 

Thermal performance, exterior folding/sliding door and bespoke kitchen.

The existing kitchen is in poor condition. This corner of the house has been extended in two direction, above support beam are making a muddle of the ceiling and under foot the concrete is thick and uneven. The original bugdet proposed for this section has been increased to accomadate improvements to thermal performance and the addition of an exterior folding/sliding door to open the kitchen up to the garden. 

Rear extension

Garden room, kitchen garden, drive way.

The existing conservatory has poor thermal performance and is inappropriate for use as a family space. It is proposed to replace it with a more thermally effective extension. Since the design of the extension will form the bulk of the works requiring planning permission, development of this design is a priority.

Rear extension; concrete pad foundation, timber framed construction, Hemcrete floor wall and roof insulation. Large bi-folding glazed doors, timber floor creating continuity to exterior timber deck.

Rear bay window; replace existing window with high-performance glazing, rebuild single skin wall with hemp and lime. Finish with lime render.

Kitchen garden and drive; lower existing ground level to minimum 150mm below damp-proof course. Remove concrete front drive and lay reclaimed key blocking from rear and side of house.

Specification

Preliminary; break up and remove concrete drive, separated hardcore waste for recycling; lift key block paving from rear patio and lay to front drive; shutter off house from conservatory and bay window for security and thermal performance; take down existing conservatory and bay window;  rebuild bay window structure and install new window.

Ground; drainage, land, surface and foul; cast pad foundation and install sub-floor ventilation

Frame;  timber frame, floor walls and roof; cast hemp and lime floor walls and roof

Roof; WBP, building paper, batten, counter batten, WBP, membrane, drainage layer, root barrier, lightweight substrate and sedum mat. Drainage via rainwater storage to soak away or existing surface water drain.

Windows; high performance glazing and bi folding doors.

Existing side extension

Garage, cycle store, utility entrance, bedroom 3,4, stair access, floor, oriel window.

To the side of the house the existing side extension has been constructed to a poor standard with little consideration to building regulation. Adding a side extension is an opportunity to turn a semi detached house into one that behaves thermally like a terraced house.

Floors; remove stud partition wall between bedrooms 3 and 4, lift the floor and remove ceilings to garage and utility room. Rebuild floor structure suitable for compliant stair access and hot water storage cylinder. Rebuild garage utility ceilings ensuring fire protection and thermal insulation, rebuild floor and stud partition walls ensuring level.

Wall insulation; fit 100mm of rigid foam insulation internally to all external walls of bedrooms 3 and 4,  overboard with plaster board and apply finish coat of plaster. Reinstate skirting boards and decorate.

Oriel window; remove existing oriel window, replace with high performance glazing.

Garage and utility; replace existing garage doors with high performance glazed doors to create entrance lobby, fit 100mm rigid foam internally to external walls, build stud wall partitions.

Specification

Insulation; cavity wall insulation, bedroom floors, internal wall insulation.

Windows; remove existing oriel window, replacement windows, utility room, bedroom 3 & 4, replace garage door with utility entrance.

Structure; rebuild stair access, stud partition walls.

Solar hot water

Services; install solar hot water flat plate collectors to rear roof, twin coil hot water storage cylinder between bedroom 3 & 4 and Worcester Bosch condensing boiler in utility garage.

Front elevation 

To the front of the house the living room and master bedroom project forward from the building line and have large external surface areas. Each room has the equivalent of two external walls, as if located on the corner of the house, so improving the thermal performance of these walls should be considered.

Outside, the walls are faced in stone, preventing exterior wall insulation. Inside, the side walls are half in and half outside the property. Internal insulation on these opposing walls would reduce the room size, whilst insulating only the exterior portion would stagger the interior wall levels. The bay window represents half of this external area. With large north facing glazing and a single skin brick wall, the bay is responsible for most lateral heat loss from these rooms. Efforts to improve thermal performance should be concentrated here.

Whilst installing high performance glazing, the single skin wall below each window could be easily removed and replaced with a better performing building fabric such as Hemcrete. This combination would significantly improve the performance of these rooms.


Rebuilding front bay; replace existing windows with high performance glazing and rebuild single skin wall with hemp and lime, finished in lime render.

Lobby; replace existing windows and door with high performance glazing, insulate lobby roof.

Attic conversion 

The attic space above your home should provide greatest potential for improving thermal performance, however the existing conversion falls short of building regulations and makes further improvements difficult.

The most cost-effective option would be to remove the existing installation, restoring appropriate levels of ventilation to the structural roof timbers, improve air-tightness and separate from the rest of the house. A generous thickness of insulation can then be installed to achieve high levels of thermal performance at minimal cost.

Removal of existing installation; remove plasterboard and mineral wool from ceilings to restore appropriate levels of ventilation to the structural roof timbers. Remove stairs and install loft hatch to create airtight separation from the rest of the house. Remove partition walls and floor, install generous thickness of insulation.

Basic attic conversion; install new floor structure, fire protection and acoustic separation. Construct new insulated roof structure within existing roof structure, ensuring ventilation to the structural roof timbers. Install new compliant staircase, partition wall and fire door.


Full conversion; install new floor structure, fire protection and acoustic separation. Construct new insulated roof structure with dormer ensuring ventilation to the structural roof timbers. Install new compliant staircase, partition wall and fire door. En-suite bathroom.