Kieran McCarthy: What to look out for when considering older properties

I would be very interested in what are the key considerations as purchasing a cottage over 100 years old could be a Pandora’s box.

Thanks, Tim. 

Hello, Tim,

Thank you for this detailed question. Yes, buying an old house is certainly a daunting prospect that no doubt fills your heart with joy and trepidation in equal measure.

It’s a bit like taking the ghost train in an old amusement park; you know you are going to get a fright at some stage in the journey, you just don’t know when.

So, where do you start? I guess when I look at an old house, as I have so often said on Cheap Irish Homes, the first thing I always look at is the masonry or walls of the house. These need to be in good condition. If the masonry (be it stone or blockwork) is badly cracked and starting to buckle, it is nearly impossible to bring it back without knocking and re-building so much of it, that it becomes unviable. So a cursory look at masonry from the outside, on all elevations, particularly around windows and chimneys is essential.

The next major element I look at is the roof. This can take many forms, depending on the age of a cottage. In your case, a 100-year-old cottage isn’t actually that old; it is a 1900s build, so advanced in many respects. As you haven’t stated otherwise, I’d imagine that it is clad in either natural or asbestos slates, both robust. 

In the case of asbestos, as long as all slates are in place, lines are straight and consistent, and none are slipping, then I would leave well enough alone as they are safe at roof level. If however, there is a big dip in the roof, or there are significant signs of water entering from the inside, you may well require a new roof. This isn’t a deal breaker and, in fact, many houses require a new roof at some stage in their life span, but this is a major investment and a big slice of your renovation budget.

Then I look at foundations. Assuming we are happy the walls are in reasonable condition and are sound and true, what story, if any, are they telling us about the foundations? Are there hairline cracks at window heads and sills, particularly local to manholes and soil stacks? If so this could very well be a sign of subsidence and that the building needs to be underpinned. 

I wouldn’t be overly phased by this as it is quite common in older buildings which have clay sewers. There are companies who specialise in this work and can underpin your house and, with the help of your engineer, certify that it has been successfully done and the structure has been finally stabilised.

So, now the critical building frame elements have been reviewed, let’s look at plastering. Is the plaster sound externally? If it is a stone building, this should ideally be a lime render to allow the stone to breathe. If this render is largely crack-free and well adhered to the building and dries out well on a dry windy day, then it is likely performing well. If this is so, then you may decide this will remain as the primary weathering defence externally and that you will add insulation internally by drylining the building.

There is one more key element that needs attention outside: drainage. In houses of this age, drains are most likely clay, meaning pipes are short with ‘push home’ joints and, in my view, should be removed and modern pvc drains with rubber gasket joints installed to protect the house from future drain leakage and risk of future structural damage. If it is in a rural location, there is probably a septic tank which should be well inspected and ensure any lead water pipes are replaced.

Finally, we look inside and the first thing to look at is the timberwork. Timber in good condition is a very good sign, meaning the house is relatively dry and keeping out the worst of the elements. Is the structural timber in sound, for example, floor joists and roof timberwork? Get a competent carpenter or engineer to assess this.

Last, but not least, is dampness. You will undoubtedly be dealing with some level of dampness in the building but some aspects are harder to remedy than others. Rising damp is probably the most straightforward and the solution depends on whether the building is built of stone or blockwork. Seek advice ultimately from a damp expert on this and these companies often treat dampness as well. It is also a great investment to get them to check the roof structure internally and advise if it needs any treatment for rot or woodworm.

After that, you are looking at improving the BER - (Building Energy Rating) - heating, electrics, insulation, airtightness, ventilation, windows. It’s by no means a small investment but it will pay dividends as you reap the benefits of lower heating bills and a far healthier living environment. You may couple this with redesign of the internal walls and joinery (kitchen, stairs, floors etc) and breathe new life back into this old home.

• Kieran McCarthy is a building engineer, director of KMC Homes bespoke A-Rated new home builder, serving Cork and Limerick and co-presenter of RTÉ property show Cheap Irish Homes. 
• For more home building information, tips and Q&A advice, see @kierankmc on Instagram and TikTok/Follow Kieran on Built Around on YouTube