Reaping the benefits of modern insulation

Your property queries answered

I own a two-bedroom apartment which was built in 1980. It is very solid but also very cold, particularly the exterior walls and floors (laminate wood laid directly onto concrete, I believe). I am considering getting the inside of the exterior walls drylined. I also want to have semisolid wood flooring laid. Could you advise on the best type of insulation for the walls and whether some form of insulation could be laid under the flooring? The BER rating is low and I wish to improve it in case I decide to rent or sell, but also to keep my heating costs down.

A As you suggest, apartments built in the 1980s were generally robust but with little regard to energy efficiency; frequently ‘hollow block’ walls were used which are in effect a single skin so energy passes directly through them by conduction.

Even if not seen, moisture is found in such constructions. The cause is usually not damp penetration from outside but condensation from within. This is worsened by modern increased levels of comfort heating and reduced ventilation that then exacerbate the feeling of cold. This mean careful consideration of how to insulate without worsening the condensation is absolutely necessary.

Usually, all properties in an apartment block will have the same problems, so if a joint approach to insulating the whole building can be agreed, then insulating externally is most effective.


If not, then insulating internally will come with some penalties such as loss of space or modifications to doors and fixed furniture. The term “drylining” is a misnomer because it refers to the dry construction method employed and not to its ability to reduce dampness. If using this method is the only option, it is essential that a vapour control layer is placed towards the warm inside; consider using a system that has an “Agrément” or NSAI certificate and insist that the details in the certificate are adhered to precisely, especially the joints and edges.

Assuming you are on the ground floor the ceiling should also be considered for insulation treatment as this is where most of your heat will go to the benefit of your upstairs neighbour.

Unless your BER consultants are appraised in the detail of the upgrades proposed, your BER will remain the same because in the DEAP software used to calculate it, the low build date defaults will otherwise be used. The heating system and ventilation method are also major factors in determining a BER. You should consult the SEAI for available grants and your local Chartered Building Surveyor for advice.

Fergus Merriman is a Chartered Building Surveyor and member of the Society of Chartered Surveyors Ireland (SCSI) Building Surveying Professional Group

Damp in the attic

Q After Christmas, three damp spots appeared on our bedroom ceilings. On investigation in the attic, I noticed a lot of condensation on the roof felt (the house was built in 1972 so I presume it is bitumen felt) which I assume is the cause of the damp spots. There is about 12cm of insulation in the attic. As there may be leakage of heat into attic, would this be the cause of the condensation? Another thing I noticed was that the top of the timber of the roof trusses were wet just under the felt, mostly at the front half of the attic. Does this suggest there is leakage of water through the felt, presumably at felt nails on trusses? I am concerned that there a danger over time that the timber in the roof trusses may deteriorate leading to replacement of roof trusses. I could put preservative on the sides of the roof trusses but not the top of the trusses under the felt. Is there any solution apart from removing roof tiles and replacing the felt?

A Your problem is common in a lot of houses. A ceiling covered with insulation will act as a barrier to prevent heat loss into the attic. This should be continuous but is often breached by gaps, such as access hatches, recessed lights and penetrating services. There is also water vapour from water tanks and ducts extracting air from showers into the attic. When the warm air meets the colder roofing felt, it will condense and form droplets.

Bitumen felt was common in 1972 but it significantly reduces air movement. As a consequence it reduces the amount of evaporation in the roof space. The wet timbers are probably condensation moisture dripping from the felt.

Most felts today are breathable membranes. These allow movement of water vapour through them and some manufacturers even claim there is no need for ventilation. However, I prefer to see ventilation as these membranes have not been tried and tested over any significant period.

Changing the roofing felt and tiles is a costly solution. Improving the ventilation, evenly distributed, is imperative and should deal with your problem. The shape of your pitched roof will determine the air path where cross-ventilation is essential.

I would advise you to ensure all insulation is free from the eaves. If there are soffit vents at eaves, then check the amount of vents and their spacing. Compare these to a continuous 10mm air gap around the building which is the recommended building regulation requirement.

Other methods include installing slate vents at a higher level than the eaves but not too far apart.

There are also proprietary continuous eaves ventilators that are placed under the front row of the slates at eave level. This requires installation by a roofing contractor.

Before undertaking such measures, I would seek advice from your local Chartered Building Surveyor to inspect the attic space.

Jim Drew is a Chartered Building Surveyor and chair of the western region of the Society of Chartered Surveyors Ireland

Extension rules

Q I am planning an extension which will be 37sq m to avoid being subject to the BC(A)R regulations. I built an extension in 1982 of 22sq m that had permission and am told that this now has to be taken into account. Is this correct?

A The interpretation as confirmed by the Department of the Environment is that the 37sq m extension requires you to comply with the full requirements of the BC(A)R regulations because with the previous extension of 22sq m the total floor area now exceeds the 40sq m threshold.

It should be noted that apart from exempted works, all extensions, material alterations and material changes of use, regardless of floor area, must comply with the building regulations. These deal with how the building is constructed, whereas the building control regulations deal with the process regarding appointments, notifications, inspection and certification in relation to compliance.

The building control amendment regulations were introduced in the public interest and designed to provide a quality assurance and quality control system to address many of the defects and legacy issues that arose in the past under the previously enacted building control regulations.

The regulations require that only competent chartered engineers, registered building surveyors or registered architects can undertake statutory roles in relation to design, inspection and certification in conjunction with a code of practice for inspection. More comprehensive evidence of compliance is now required than existed under the 1991 regulations.

Statutory appointments and commencement notices are required, in conjunction with statutory undertakings and declarations by clients, designers, assigned certifiers and builders. These need to be submitted to local authorities at the outset with adequate designs and supporting documentation, including inspection plans of key milestone inspections to show that the building meets the requirements. On completion the work must be signed off by the builder, assigned certifier and designer and accompanied by ancillary certificates from other key professions and tradespersons.

The old system relied disproportionately on opinions of compliance provided by construction professionals to clients on behalf of solicitors and lenders. They were often based on no more than superficial inspections of completed structures and could not be fully relied on as evidence of compliance.

In conclusion while there are additional costs associated with this system, it should provide for more than just administrative efficiency. The cost should also be minimal over the lifecycle of the building.

If properly carried out, it should provide for peace of mind as the old system relied on self-compliance in the absence of proper checks and balances.

The regulations should give greater comfort to the applicant and to future purchasers.

Kevin Sheridan is president of the Association of European Building Surveyors and Construction Experts, is a Chartered Surveyor and former president of the Irish Building Control Institute

Send your queries to or to Property Clinic, The Irish Times, 24-28 Tara Street, Dublin 2. This column is a readers’ service. Advice given is general and individual advice should always be sought