Question
I recently purchased a house and was informed by the agent at the time that one of the bedrooms was a loft that had been converted a number of years prior. Recently, my wife and I have noticed that the room gets particularly cold during the final months of the year. The ceiling has been plasterboarded. Is there anything we can do to retain more heat?
Answer
A loft/attic space sold as a habitable room, must have planning permission for its use, ie a change of use has occurred from attic to habitable room. Planning permission should have been obtained by the owner at the time the work was completed, and may form part of documents exchanged during conveyancing. As such, the refurbishment should have been carried out in accordance with building regulations, including the provision of space heating, compliance with fire regulations, ventilation and sufficient insulation within the roof void. You may want to investigate this further.
With regard to increasing the temperature in your loft, ensuring adequate insulation is vital. Up to 30 per cent of the heat produced in your home can escape through the roof if it is not insulated, so it is important to ensure that it is insulated appropriately.
If an attic is used as a habitable room, insulation is provided within the slope of the roof, ie between the rafters. Unlike insulating the floor of an attic (where insulation is placed between the joists and counter- rolled over the timbers) the space available to insulate is limited by the depth of the rafters.
The choice of insulation used is determined by the type of felt on the roof. If the felt is an older, non-breathable felt, then a gap of 50mm should be left between the insulation and the felt to prevent the formation of condensation. This reduces the usable space you have to insulate to a depth of about 100mm.
I recommend that, initially, confirmation be obtained on the felt type and that the rafters are insulated along with the room walls. Subject to confirmation on felt type and existing insulation, there are a number of options available for retrospective upgrading of insulation.
Provided there is no existing insulation between the rafters, and a breather membrane felt is installed, you could consider the installation of blown insulation. Subject to manufacture guidelines and initial preparation work this can be blown between the rafters without removing the plasterboard ceiling.
Assuming access to the eaves, you may be able to slide cut-to-width sheets of rigid polystyrene up into the space between the room ceiling and the roof slope, and also to insulate the room walls from the loft side with slabs of polystyrene set between the wall studs.
If there is already insulation between the rafters, additional insulation can be provided to the underside of the ceiling in the form of an insulated plasterboard slabs.
The ease of installation will be subject to the existing lighting arrangement within the attic (spotlights versus standard drop pendant). The installation of plasterboard slabs will, however, reduce the ceiling height within the room.
Andrew Ramsey is a chartered building surveyor and chartered project management surveyor and is chairperson of the building surveying professional group of the Society of Chartered Surveyors Ireland