Kieran McCarthy: How to weather-proof a coastal home

How do I ensure my seaside house doesn't look weather-beaten in 10 years?

Kieran McCarthy: "Invest in high-quality marine grade windows that have been specifically designed for your environment. I cannot stress enough the need for quality here."

Hi Kieran,We are building by the coast. What should we do differently so our house wears well and doesn’t look weather-beaten in 10 years?Jessica, Co Clare

Hi Jessica,

Thanks for your question. As someone who also lives by the coast, I love that there are so many wonderful advantages. When the sun shines and everyone flocks to the beach, you’re already there and can enjoy the sunshine with endless beachside walks and swims.

But in the depths of winter it can be very different...

Now you can find yourself in the epicentre of every storm that makes landfall on your coast. From a building point of view, wind and salt are your biggest enemies so your builder and design team need to know exactly what they are getting in for. Let’s dig at this in more detail.

When we moved to the coast the old house we bought was wearing quite well, but it had been overdesigned in many ways. What I mean by that is that it was built from concrete block walls, with a slate roof, and PVC facias, gutters, and windows. In fact, none of the windows facing the sea opened. I don’t know why. Maybe the previous owner thought they would get stuck due to the salt or maybe they would be too exposed in winter. To be fair, they were right to be cautious but there are more options available once you know where the risks actually lie.

Weather-proofing

Firstly, everything facing outwards needs to be marine grade.

The most important element here is of course your windows. They will bear the brunt of harshest winter weather conditions and any sign of breakdown will prove major in no time.

Invest in high-quality marine grade windows that have been specifically designed for your environment, particularly an oceanic marine environment like I expect you will find in Co Clare.

Yes you can have openings facing the sea but the more you invest in the windows generally, the more robust these openings and hinging systems will be. I cannot stress enough the need for quality here. Given the sea views, it is likely you will have a lot of glazing facing south and west. As a result I would recommend triple glazing, this will help with solar gain and heat loss in summer and winter.

Salt-proofing

The other key building product that you will likely have sited near the elements is the outdoor unit of your air to water system.

This mechanical unit will literally draw in salt-laden air (to extract its heat) so this unit needs to be able to withstand salt in particular. To be fair most air to water units are very robust, but make sure the manufacturers are aware of this environment and that all your warranties will remain in place.

Next is rust. The windborne salt will find its way into every nook and cranny of your house. As I look out my window I am reminded of two outdoor lights we purchased for our garage; the brackets have now literally disintegrated (they are on a list to be renewed shortly). Every fixing in your house (nails, screws, bolts, nuts, washers) needs to be stainless steel, otherwise it will rust within a few months and eventually fail. You will have to police this on site and ensure every new contractor is acutely aware of this, particularly those working on the sea-facing elevations and gardens.

When the building is finished you need to make sure that anything you build or buy for your garden is similarly designed to last for at least 10 years in this harsh oceanic environment.

Wind-proofing

In winter in Ireland, most winds that you experience over land have developed over the seas and oceans where they can build unobstructed for hundreds or thousands of miles. When these winds reach your coast they will put every aspect of your house under immense pressure. Canopies, overhangs, railings, windows, even nearby trees (if they will grow) come into focus.

We were watching a rugby match on television in March when a mini tornado made its way up from the sea; the windows in our sitting room began to flex, almost to the point of no return. When the wind dropped a minute later I found patio furniture had been lifted 20 feet into the air, then fell to the ground and were smashed to pieces (and that was in spring).

In particular, your engineer will need to design the entire house for a heavy coastal wind loading with a considerable factor of safety.

Sun-proofing

You also need to be aware of the sun. It’s not as major a concern as wind or salt but I would avoid timber cladding or decking for example. They will get parched and buckle in the sun and salt and will decay them quickly. The maintenance will be too great. I would recommend a sand cement render, or zinc, or slate as robust exterior finishes.

Any exposed steel will naturally need to be galvanised (which would normally be the case in any event) and avoid brown or even black PVC as it can bleach in the sun.

Gardening

Finally, planting anything in your garden will be a challenge. Few plants enjoy salt and wind and even though you will experience little enough frost by the sea, you will likely find it difficult to get your garden going for a few years.

Take inspiration from neighbours’ gardens.

I remember someone working in a garden centre telling me ‘you will just have to persevere for a few years’ — and he was right. I am painting a slightly bleak picture here but these impediments will fade into insignificance when you get used to living by the sea.

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Kieran McCarthy: "The more you invest in the windows generally, the more robust the openings and hinging systems will be."

• Kieran McCarthy is a building engineer, and director of KMC Homes, who specialise in designing and building luxury homes in Cork. He also presents the RTÉ TV show ‘Heat My Home’, showcasing deep retrofits in Irish homes; kmchomes.ie
• @kierankmc has more home-building tips, information, and Q&A advice;
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