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...and thanks for stopping by. I'm Claire Douglas, DIY and home interiors writer specialising in money-saving and creative home interior projects. I've spent years developing my 'bespoke on a budget' approach to DIY and home interiors and I love sharing all my tips and tricks in tutorials and posts here on my blog, in articles I write for some of the leading titles, in the press, on Instagram, Tiktok and my online course.

Claire Douglas
- Feb 4, 2023

Roof tile vents: the simple solution to loft condensation

Updated: Nov 2, 2023

Ventilation issues causing loft condensation? Find out if roof tile vents are the answer you've been searching for.

This week, was one of those weeks when you spend a load of money on important (but boring) house stuff. Those home maintenance jobs that you can't really enjoy as such when they are done, but you know that if you hadn't spent the money on them, you'd be dealing with unpleasant consequences that would probably cost you more in the long run.

We had three separate jobs completed this week, which I'll cover in two blog posts. I thought I'd write about the work we had done (and why), mainly because the issues that prompted us to take action are pretty standard for houses in the UK, so there's a good chance you might be interested or know someone who is. First up, loft condensation...

What causes loft condensation?

Condensation is moisture previously held as vapour in the air that has turned back to water after hitting a cold surface. Loft condensation occurs when heat from the house below escapes into the loft space and hits the cold roof. Other factors can impact the severity of the condensation for example, insufficient loft insulation can allow more heat to escape, and poor ventilation means warm moist air is trapped.

I've been waffling on about condensation a lot over the past few weeks! As well as waffling, I've been researching and sharing the causes and remedial measures in the home, as it seems to be an issue for so many people in the UK due to the cost of living crisis. Soaring bills led to people rationing their heating and colder houses caused a rise in condensation which can lead to damp and mould.

Condensation in the loft

Loft condensation was a new addition to my 'house issues that need dealing with' list, although, in hindsight, I just wasn't aware it was happening, as opposed to it only starting recently. Back in November, I noticed a small patch in the corner of the bathroom ceiling that looked a bit damp, but it only appeared when the bathroom was steamed up, so I thought it might be condensation forming from poor loft insulation (ours is rubbish! It's well under the recommended thickness and on 'the list'). Over the next 2-3 weeks, small grey mould-like patterns appeared. so we looked up in the loft and were pretty shocked to find the inside of the roof was absolutely dripping wet. When I say dripping wet, I'm not exaggerating. The water literally ran down the felt and dripped off the beams, mould was starting to form and it smelt damp and musty. Good times!

condensation collected on the underside of roof membrane

At the time of discovering this problem, we were in the grips of the Troll of Trondheim think sub-zero temperatures, snow and ice, which probably exacerbated the issue by increasing the temperature variation between the loft and the rest of the house. We could also see that the loft insulation was bunched up in the corner, directly above the damp patch. It later transpired that this was the work of a nesting squirrel who had inadvertently (I'm giving the squirrel the benefit of the doubt here and assuming the eaves-covering wasn't an act of malice!) blocked the ventilation above the corner of the bathroom ceiling.

Unknown loft ventilation issues

You might be wondering why we didn't know this was happening, but to put things in context, we can't use our loft for anything sensible, like storage, as it's not boarded, so rarely open the hatch. For some reason, they built the house with the lowest-pitched roof you can imagine. It would be perfect for Sylvanian Families or 'Borrowers' (showing my age with those two references...80's babies, IYKYK!). You can't get up in the loft because there simply isn't room to even crawl around, let alone stand up. There's a large, empty water tank taking up a lot of room from where previous owners had an emersion tank and an old-style boiler. We had a combi-boiler installed when we moved in (that was a fiasco in itself as the plumber we used turned out to be a total cowboy, leaving the job half finished with several serious (illegal) issues. I might write a post about it one day as we learnt a lot as a result and now know the red flags to look out for. We'll see... the plumber in question is now a chef and I've just about repressed the traumatic memories!

Anyway, I digress; back to mouldy lofts! So we'd identified the condensation and knew we needed a plan. By this point, it was just before Christmas and every loft or roofing contractor that I phoned (which was MANY) gave a little laugh when I enquired as to their availability. Some were booked up until April, some had voicemail messages that essentially said, 'don't bother leaving a message', and those I managed to speak to advised they had been inundated with people in exactly the same situation as us.

Tile vents for the win

Finally, we found a company with an available surveyor in January. In the meantime, we used a dehumidifier for hours at a time which removed gallons of moisture from the air but still couldn't keep on top of the condensation.

Dried out roof membrane after tile vent installation

The surveyor came and advised that tile vents would solve all our ventilation issues and recommended bulking up the insulation once the loft had dried out. Fast forward to this week, the tile vents (8) were fitted and we were shocked at how quickly they worked. Within three days, the previously soaking roof felt was dry as a bone (really!). See below for the transformation. Brilliant!

In short, if you have condensation in your loft space, I highly recommend looking into tile vents.

What are tile vents?

Tile vents take the place of a standard roof tile at regular intervals along a roof. They have an inbuilt gap that allows air to flow in and out of the roof whilst being protected from the elements. The ventilation area of the tile vent usually has a mesh or grille cover to prevent animals, birds or insects from getting in.

How many roof tile vents do I need?

The exact number of tile vents a roof needs depends on the volume of loft space beneath. The rule of thumb (after a quick research on the web) appears to be one square foot of tile vent per 300 square feet of ceiling space. There are different types of tile vents, each needing specific positioning on a roof to work effectively.

tile vents fitted to a concrete tiled roof

Do I need tile vents?

In new buildings, there are building regs that specify exactly how a roof space should be ventilated. If you're interested BS 5250:2021 - Management of moisture in buildings makes for an interesting read! Optimum ventilation is not usually achieved through a single solution but instead by harnessing the benefits of several measures, including some of the following eaves vents, soffit vents, dry ridge (mandatory for new roof installations), fascia vents and tile vents. Updated British Standards are not applied retrospectively to buildings, but if you are experiencing issues, then it's definitely worth investigating some of these measures. The exact measures that are suitable for your roof will depend on factors like the shape, size, construction material and pitch.

How are roof tile vents fitted?

Roof tile vents are fitted from the outside after removing individual tiles and replacing them.

Do you need scaffolding to fit tile vents?

Happily, the company we used were happy to fit the roof tile vents using roof ladders so scaffolding was not required, making the whole job affordable.

The main takeaways from all this malarky are as follows...

- check your loft for condensation in winter,

- check your loft insulation is thick enough and not blocking eaves ventilation,

- have a survey done if you think you need extra ventilation, and

- consider having roof tile vents retro-fitted if condensation is an issue

If window condensation is your issue then read the post here where I tested out this £3.50 window-film to prevent condensation. You might also be interested in ways to stay warm in winter without putting the heating on.

Thanks for reading. I'd love to keep you up to date with future DIY, decorating, interior styling, and upcycling projects, if you would like to receive my (not more than weekly & no spamming I promise) emails then please subscribe (scroll down to the box at the bottom of the page).

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