Kieran McCarthy: What to consider before working on your roof

Roof works are best left to a construction company.

Hi Kieran,
Can you help me please? I need to get some work done at home and I’m wondering if it would be advisable to use a roofing contractor to replace the roof on my 1960s house or whether a general construction company would be OK to use. I’m new to the renovation game and would appreciate any advice.
Many thanks, Judy

Hello Judy,

Thanks for your question. Sorry to hear you are having roof issues at home. Replacing a roof on a house of any age is a daunting and expensive task and it is certainly wise at this juncture to ask what type of company would be best to carry out the works but to give you a clearer picture, let’s look at what could potentially be involved.

Whereas I am clearly not familiar with your particular house, there are a few key stages to any roof build that should cover most of the works for your house. I am assuming at this stage that you have had an engineer inspect the property to assess the works required and advise if any of the existing roof structure also needs replacement. (It may be that if the roof had been leaking for some time that some of the rafters may be rotten.) Once you have a full report on what needs fixing, you can set about planning the works.

The first thing you need for a roofing project is a reasonable weather window. You don’t want very unsettled or extreme weather. Heavy winds or icy cold weather can create dangerous conditions for works at a height and you clearly need a reasonably dry spell. In any event, you will need to have a temporary protection tarpaulin to guard your internal building against the inevitable showers. (I am assuming that you will be moving out of the house for the vast duration of these works.) The next stage is to stand the required scaffolding around the building to allow you safe access and to provide fall protection externally. You will need to get an electrician to disconnect any lights and sockets in the vicinity of the roof internally. Now you are ready to begin the main body of the work.

Kieran McCarthy: 'The first thing you need for a roofing project is a reasonable weather window.'

Your roofing contractor can now begin to strip the slates and carefully stack in your designated storage area (keeping your tarpaulin at close hand just in case). Next you can remove the battens and any old sarking felt and lead if present. Now you have a bare roof and all the existing structure can be seen in plain view. This is an ideal opportunity to have your engineer inspect the old structure to advise on what, if any, roof members need replacement. It would be a good idea now to have a plumber replace any old lead water tanks and pipework, if present, and generally clean out any dust and debris from your attic.

Now you are ready for the rebuild. Your roofer can begin by replacing the affected roof timbers. It would probably be worth getting your structure sprayed for woodworm too (specialist contractor). I would also check any existing chimneys which may need repair, bracing, or replastering.

Next it’s time to close it all up again. Now you will apply a new breathable felt, and batten layer to your roof structure. (It may be that your roofer will need to pack some of the battens if your roof structure has sagged a little in the middle.) You can now set about refitting your old slates or indeed fit new if that is your plan. You will finally need to install any new lead flashings around chimneys and the like and install any new ventilation as directed by your engineer. Any facia boards, backing boards, gutters, and downpipes should be checked to ensure they are clean and sound and replaced where necessary. One final inspection and snag list and you are ready to start demobilising externally and your scaffolding company stripping the scaffolding.

Internally you may need to have a plasterer remove and replace some or all the ceilings under the roof as they will have been affected by the roof traffic during the strip and rebuild, particularly if you have old lathe and plaster ceilings. Your electrician can now rewire the affected roof electrics and your plumber reconnect the water and heating tanks. Finally a painter can repaint all the necessary ceilings and make good externally where required.

So, what we have seen is that outside of a roofing contractor we also need a certified scaffolding company, an electrician, a plumber, a woodwork specialist, a plasterer and a painter, and of course an engineer. Whereas you could certainly source all these contractors yourself, and if managed properly it may in fact be cheaper, but you would need to manage this project full-time for the duration of the works and you would need to have all the experience and expertise to manage a fast-moving project such as this. Mistakes lead to serious delays and costs and a project like this would not be for the faint hearted. A building contractor would bring all these tradespeople to the table, manage them, and provide a warranty at the end of the works for all aspects of the project. Yes it would cost more but in my view, a good investment. Now, all you need is to find a building contractor who isn’t booked up for the next six months.....

• Kieran McCarthy is a building engineer and director of KMC Homes, a bespoke A-Rated new home builder, serving Cork and Limerick. He is also co-presenter of the RTÉ property show Cheap Irish Homes;
• Follow Kieran on instagram @kierankmc for more home building information, tips and Q&A advice;
• You can also follow Kieran on the Built Around You Youtube channel and @kierankmc on TikTok.