They're beautiful. They flood the room with light. And they're a pain in the arse to open.
Velux windows are the single best thing about an attic conversion. They transform what would be a dark box into a bright, airy space with views of the sky. But there are practical things nobody mentions until you're living with them.
The standard Dublin setup
For a typical Dublin semi-d attic conversion, the standard configuration is:
2 large
Main living space
1 small
Ensuite (ventilation + light)
Most conversions will have two large windows for the bedroom or living area and a smaller one in the ensuite for ventilation and natural light. Some setups include an extra small window if there's a kitchenette or second room, but three rear-facing windows is the most common configuration.
All windows go to the rear of the house. This is important: rear-facing Velux windows in a standard attic conversion generally don't need planning permission. Front-facing windows or dormers almost certainly do - they change the appearance of the house from the street and may overlook neighbouring properties.
Planning permission note
Rear-facing Velux windows in a standard conversion are typically exempt development. Front-facing or side-facing windows, dormers, and any changes that alter the roofline visible from the road will likely require planning permission. Check with your builder or your local planning authority if you're unsure.
Window sizes explained
Velux windows come in a range of standard sizes identified by letter-number codes. The two most common sizes used in Dublin attic conversions are:
The narrower window, typically used for ensuite bathrooms where you need light and ventilation but space is limited. At 55cm wide, it's compact but lets in a good amount of light for a small bathroom.
Source: RoofnStop Ireland - Velux Window Size Chart
Check your quote
Some builders will spec smaller (cheaper) windows without telling you. Always ask: "What size Velux windows are included in the quote?" The difference between a CK04 and an MK04 in your main room is significant - don't let someone save €200 on a smaller window that you'll regret for years.
The reality of opening and closing them
This is the bit nobody tells you. Velux windows in a sloped ceiling are not like normal windows. You don't just reach out and push them open. They're above you, set into the slope, and depending on your furniture layout they can be genuinely awkward to reach.
Centre-pivot Velux windows have two positions: a ventilation position (cracked open a few centimetres at the top for airflow) and fully open (the window pivots on a central hinge so you can clean the outside glass from inside). The ventilation latch is at the top of the window - which is the highest point on the slope. The main handle is at the bottom of the window.
If you have a bed or a desk directly under the window, reaching that top latch means leaning across furniture. It's doable but it's not elegant. Velux supply a telescopic rod/wand for exactly this reason - do not lose it. It's the only comfortable way to open the ventilation position from below.
Think about furniture before fixing window positions
If your bed is going under the Velux, you’ll be reaching across it every time you want ventilation. Consider whether the window position and your furniture layout are compatible.
Keep the telescopic rod accessible
Velux supply a rod for reaching the top ventilation latch. Hang it on a hook near the window. If you lose it, you’ll be standing on the bed trying to reach the latch by hand.
Consider electric opening for hard-to-reach windows
Velux make electric and solar-powered opening versions. More expensive, but if a window is in a particularly awkward spot (above a built-in wardrobe, for example), the remote control is a genuine quality-of-life upgrade.
Blinds - electric vs manual
You will need blinds. An attic bedroom with south or west-facing Velux windows and no blinds is an oven in summer and a lighthouse at 5am in June. The question is what type.
We went with Velux electric blackout blinds and they've been one of the best decisions of the whole conversion. They pair together so you can open/close all blinds with one button press. They come with a wall-mounted, battery-powered switch (no wiring needed). There's also an app for phone control, though honestly the wall switch is all you need day-to-day.
The main advantage is practical: manually operating a blind on a skylight above your head - especially one you can barely reach - is annoying. Doing it twice a day (close at night, open in the morning) gets old fast. Electric blinds remove that friction completely.
Budget around €200-400 per window on top of the window cost, depending on size and blind type (blackout, duo, etc.).
Source: Velux Ireland - Windows, Blinds & Accessories | RoofWindowBlinds.ie - Velux Blackout Blinds
Velux vs cheaper alternatives
Velux is the market leader for a reason - the build quality, sealing, and long-term reliability are excellent. But some builders will use cheaper roof window brands to save on costs. This isn't necessarily a problem, but you should know what you're getting.
If the quote says "roof windows" rather than "Velux windows," ask which brand. Alternatives like Fakro and Keylite are decent products, but the blind and accessory ecosystem is smaller. If you want electric blinds, remote opening, or specific accessories, Velux has the widest range and the best aftermarket support in Ireland.
What to ask your builder
"What size Velux windows are included in the quote?"
Get the exact size code (e.g. MK04, CK04). Don’t accept ‘standard size’ — there’s a big difference between a 55cm and a 78cm window.
"What brand of roof window are you using?"
Velux is the gold standard. If they’re using an alternative, ask why and check that blinds and accessories are available for that brand.
"Are blinds included in the price, or an extra?"
Blinds are often not included in the base quote. Clarify this upfront so you can budget for them. Electric blackout blinds add €200-400 per window.
"Can you position the windows so they’re reachable from the floor?"
The lower the window sits on the slope, the easier it is to reach the handle and ventilation latch. Discuss this before they cut the roof.
The bottom line
Velux windows make the room. They're the single biggest factor in whether your attic feels like a proper living space or a dark afterthought - and they directly affect your BER energy rating through their U-values. Go as big as your roof and budget allow. Get electric blinds if you can stretch to them - the daily convenience is worth it. And think carefully about where the windows sit relative to your furniture, because you'll be opening and closing them for years to come.
Not sure what windows suit your conversion?
Our free planning report includes window recommendations based on your house type. It takes 2 minutes.
Try the Planning Tool