Flats: period conversion

Heating system

Conversion to flats creates a number of practical problems with regard to fuel choice. Gas can be separately metered if there is a gas connection, and would be a good solution with combination boilers serving individual flats. However, monitoring and charging for fuel use to individual flats from communal oil or LPG storage tanks may not be practical.

The low delivery temperature from ground source heat pumps would not be suitable for radiator-based heating, and under-floor heating is not practical on suspended timber floors unless they are replaced by new insulated solid floors, which would only be practical on ground floors anyway. Air source heat pumps would be worth considering when they become more available. Overall most practical solution is likely to be off-peak electric storage heating.

Insulation measures

Walls

External insulation may be practical, but would cover up period features which may need to be retained. For individual flats the most appropriate measure would probably be internal insulation, supplemented by flexible insulated linings in areas where the additional thickness of internal insulation creates problems.

Glazing

Timber sash windows are often difficult to draught strip effectively, particularly if frames have racked due to settlement. Because of the relatively large proportion of glazed area on external walls high performance double glazing would be beneficial provided there are no restrictions from the planning perspective. Alternatively secondary glazing may be a good option, but attention needs to be paid to egress in case of emergency and need for rapid ventilation in 'wet' rooms such as bathroom and kitchen.

Floors

Suspended timber floors can be quite draughty, especially if square edged boards have been used. Effective draught sealing of the entire floor (for example by applying hardboard or similar and sealing around skirtings with mastic) would increase comfort levels markedly. If floor boards are replaced insulate between joists.

There may be an assumption that floor insulation/draught proofing is only an issue with ground floor flats, but in many older properties air infiltration into the under-floor space at first floor level and above can occur from a number of sources. These include soffits of porches and passage ways, the junction between the floor and a bay, and via the eaves box in attic flats. Depending on when the conversion was carried out some of these problems may have been dealt with as part of the requirements of building regulations, but checks should be carried out.

Roof

Where possible loft insulation should be upgraded to 250 mm, taking care not to block ventilation paths. In the conversion of older properties the loft / attic is quite often converted into living accommodation. If the roof was not insulated when the conversion was undertaken it can be quite difficult to do so retrospectively. In these situations internal lining with insulation-backed plasterboard can be effective.

In many loft conversions storage space is often created behind studwork at eaves level. This can be a source of draughts if not detailed properly, and steps should be taken to rectify them. Doors and hatches leading to unheated spaces should be insulated and draught stripped and fitted with a lock or catch that compresses the door or hatch against the draught strip when closed.

In many older properties the first floor rooms can be partially within the roof structure, leading to a sloping portion of ceiling where the rafters meet the external walls. This area is difficult to insulate from above and is often best treated internally with insulated plasterboard.

Ventilation

Background ventilation should be provided in habitable rooms. Trickle vents can be fitted to existing windows, but this may not be practical for some types of frame such as sliding sash windows. In these situations through the wall vents can be installed, although occupants can easily seal them off.

Passive stack ventilation in kitchens and bathrooms can be fitted during the conversion process, although routing ducting may be difficult in ground floor situations - flats in upper floors may be more straightforward. Extract ventilation, preferably with heat recovery, should be fitted in situations where passive stack ventilation is not practical.