Fixing slate roof tiles

Slate roofs are one of the most durable and long lasting roofs there are. In fact, a good quality one could last well over 100 years! However, just like any roof, slate roofs can become damaged and will need fixing or replacing eventually. Read on to have all your questions about fixing slate roof tiles answered.

Signs you might need to fix slate roof tiles

Wondering how to know whether your slate roof tiles need fixing? Here are some of the common signs that there’s damage to be dealt with:

• Water damage to ceilings. This can indicate that there’s a problem with your roof. Just be aware that the damaged roof tiles are unlikely to be directly above the damp patch on your ceiling
• Missing or broken roof tiles. If you can see that there are roof tiles missing, broken or out of place, this will need to be dealt with. If the damage is all in one area, this can be a sign that it’s been caused by something external, like wind damage or faulty chimney flashing
• Rows of slates out of line. If you spot that the lower edges of a row of slate roof tiles is out of line, this can indicate a problem called ‘nail sickness.’ Here, one fixing fails on multiple slates, causing them to twist
• Slate tiles make a dull sound when tapped. Okay, so this one might be difficult to notice. But if you spot any loose slates, tap them square in the middle with a hammer and note the sound they make. If you hear a dull sound (as opposed to a bright ringing), it may mean the slate tiles are porous and no longer usable

Problems that lead to fixing slate roof tiles

So, you’ve spotted that there’s an issue with your slate roof. But what’s actually wrong with it? Here are some common problems that could cause you to have to fix your roof slates.

Slate tile fixings

Slate tile fixings will usually give up the ghost before the slate tiles themselves, which are extremely durable and long-lasting. Over time, the nails used to fix slate roof tiles in place will corrode, which is commonly known as ‘nail sickness.’ When nails corrode, slates will slip or split.

If your slate roof has been poorly installed, this can also lead to issues. For instance, if your roofer uses nails that are too thin, these can slowly cut through the roof slates.

Poor quality slates

Another issue, although less common, is with the quality of the slates themselves. If your slates aren’t up to scratch, they can delaminate, which is when they split into layers.

Bad-quality roof slates can also be less resistant to pollutants. This can lead them to soften and degrade more quickly.

Mechanical damage

No matter how well your roof is installed, there are some things you can’t control. Mechanical damage, such as frost or wind damage, or objects falling on your roof, is a common cause of broken roof slates.

The good news is that this kind of damage will often only affect a relatively small area of your slate roof.

Fixing roof slates

If it’s deemed that your slate roof can be repaired, you’ll usually need to replace or re-secure broken, slipped or missing slates.

Missing roof slate

If you’re missing a roof slate or several, the fix will just involve fixing another in its place.

This involves using a copper wire, known as a tingle, and a fixing nail to secure the new tile in position. The slates in the row above will need to be carefully raised in order to accommodate the new roof tile.

Broken roof slate

Broken roof slates need to be replaced in the same way as missing roof slates. But if the slate is still attached, it will need to be removed first.

This will involve pushing a tool called a slate ripper up between the roof slates to remove the fixing nails without lifting the surrounding roof tiles too much.

Slipped roof slate

If your roof has slates that have slipped or twisted out of position, the slate can simply be reattached using a tingle and fixing nail as above.

Just be aware that loose slates are often caused by nail sickness or the slate itself breaking down and disintegrating around the nail holes. If this is the case, it often signals that the roof is reaching an age where it will need to be replaced, as all the nails and slates will likely be ageing in the same way. As such, fixing a single roof tile that’s slipped should usually be a temporary solution to bide time until complete re-roofing.

Can I fix a slate roof tile myself?

Fixing a roof involves working at height. So, it’s a dangerous job that you shouldn’t undertake without the right experience. It’s also important to note that if the work isn’t completed correctly, it could lead to costly problems later down the line – or you could even end up damaging the surrounding slate roof tiles.

For that reason, we’d recommend leaving this job to the experts. Not only will they be able to fix your slate roof quickly, effectively and safely, but they’ll also be able to point out any other issues with your roof that you aren’t aware of. That way, you can make sure that you keep your roof in the best condition possible, and avoid any small problems from developing into bigger and more expensive issues. One way to keep an eye on your roof is through a drone survey.

The typical slate roof repair cost is around £465 per m².

Replacing a slate roof

Even though slate roofs can last over 100 years, at some point, the time will come when your roof needs to be replaced completely. As a general rule, it’s worth considering a roof replacement – as opposed to a repair – if:

• More than 20% of the original slate tiles need to be fixed
• There are issues scattered all over your roof, rather than just limited to one spot

In this case, investing in fixing slate roof tiles will probably no longer be cost-effective and complete re-roofing could be a more sensible option.

Of course, investing in a new roof – especially a slate one – is a big investment. A new slate roof costs on average £184 per m², not including labour. So, make sure you get plenty of quotes and make any decisions about material replacement together with your local planning committee.