Will converting our attic increase our Local Property Tax?

May 2013

Question

We’re planning to extend into the attic, creating two extra bedrooms on a four-bed house. Although we can’t sell the house as a six-bed in the future, is this likely to increase our property tax?

Answer

Converting attics, although a very regular occurrence, can be a very complex matter. The first issue to consider is the type of roof. Basically there are two categories — traditional timber roofs and prefabricated trussed timber roofs. The traditional type roofs are generally easy to convert and can be completed at a cost of about€15,000 to €16,000. In reality, the majority of houses, particularly in typical housing estates, are of the prefabricated trussed type. This type of roof is very effective in that there is a minimal amount of timber, which creates a good economy for the builder at the time of construction, however unfortunately they do not lend themselves to easy conversion. Unfortunately many builders don’t realise this and roofs are often converted without proper thought given to the structural design.

A trussed roof should not be converted without first seeking professional advice from a structural engineer as there will be a serious risk of damaging the roof. If a trussed roof has been converted and this has not been properly done and is not signed off by an engineer, then the subject property is actually worth less than if the property was not converted at all. The approximate cost of carrying out a conversion to a prefabricated trussed timber roof is more likely to be in the order of €25,000, as you are effectively building a separate roof inside the existing roof structure.

The other issue to consider is that of ‘regulations’ and this is related to the question of whether the converted space is a “habitable” space or storage space. If the converted space is intended to be a proper habitable space, ie a living room or bedroom, then there are a whole host of building regulations to be complied with which will add even further cost to the construction costs. However if the converted space is just being considered as a storage room, then most of the regulations can be avoided. The majority of converted attics in Dublin are non habitable space, and in our practical experience, a frighteningly high proportion of these have not been done properly, and thus, it is extremely important to ensure that the attic conversion has been properly signed off in the first place and that you get a proper survey done to ensure that you are not acquiring a problem.

With all the above in mind, and assuming that the attic conversion has been carried out to a proper standard, then I do feel that you could expect to pay approximately €25,000 more for a house that has been converted over and above a similar house which has not been converted.

Val O’Brien is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland.