Draughty Roof Window? Seal and Installation Checks for Dublin Homes

A cold patch beneath a roof window can make an attic bedroom or home office uncomfortable. It does not, by itself, tell you whether a seal has failed, a ventilation flap is open, or the installation around the frame needs attention.

For Dublin homeowners, the useful first step is to record where the cold air seems to come from and when it happens. This guide explains the clues to share with a roofer and the questions to ask before agreeing to repairs.

Is outside air entering, or does the glazing feel cold?

There are several different situations that can feel like a draught:

• Air through an open ventilation flap or inlet: a designed route for fresh air, depending on the window model and settings.
• Air at the opening sash: a possible closing, alignment or gasket problem.
• Air around the fixed frame and internal lining: a reason to investigate the connection between the window and roof construction.
• Cool air moving below the pane: air inside the room can cool against cold glazing and move downwards without an outside-air leak.

VELUX's Daylight, Energy and Indoor Climate reference book describes both damaged-gasket draughts and downward air movement near cold panes. These are different mechanisms, so applying sealant around the window is not a diagnosis.

An inspection should establish which explanation fits your window. More than one issue may be present.

Start with the controls and closing action

If the window is safely reachable from the room, check its normal operating instructions. Some roof windows can admit ventilation air while the glazed sash stays shut. For example, VELUX describes this function on traditional windows with a ventilation flap.

Record the position of the handle or ventilation control and whether the sash closes normally. Avoid forcing a stiff handle, adjusting hinges yourself, or assuming every model operates the same way.

Useful details to note include:

• Whether the sensation comes from the top control bar, one side, or below the glass.
• Whether it changes noticeably in wind or remains similar on calm days.
• Whether the window has recently become harder to close.
• Whether the problem began after installation, decoration or other roof work.

Do not permanently tape over ventilation openings to solve discomfort. Ask how the window's ventilation fits the room's overall ventilation arrangements.

Can worn roof-window seals cause a draught?

Yes, depending on their condition and fit. VELUX's Irish draught guidance explains that gaskets on older windows can deteriorate and become rigid, allowing air to penetrate. It advises owners of newly installed draughty windows to contact the original installer first.

From a safe indoor position, you may be able to photograph a visibly split, displaced or missing section of seal. Leave dismantling and replacement to someone familiar with the window. A generic adhesive strip may interfere with closing or conceal the actual fault.

Before ordering parts or accepting a quotation, ask:

• Which seal or operating component is affected?
• Has the sash alignment and closing mechanism been checked?
• Is the proposed part compatible with the exact window model?
• How will the closing action and reported draught be checked afterwards?

Send an existing model label photograph if you have one. Do not lean out, use an improvised ladder, or force the window open to find it.

What if the cold area is around the plaster reveal?

The reveal is the lined recess between the room and window frame. If the discomfort seems to come from that recess, the assessment may need to consider insulation and the air-sealing connection behind the finish, alongside the window itself.

VELUX's Irish lining-system guidance explains the separate roles of insulation around the opening and a vapour-tight connection to the window. A neat-looking plaster finish does not establish what is behind it.

Ask the roofer what can be checked without disturbing the lining and whether any limited opening-up would be needed. Agree the inspection scope and making-good work before the finish is removed.

For a converted attic in Lucan or South Dublin, the room's roof insulation and ventilation arrangements may also need consideration. The right repair follows the findings at the opening; the location alone does not identify the cause.

Keep draughts, condensation and rain leaks separate

A draught without staining and water appearing after rain need different investigations. If you also see damp marks, tell the roofer when they appear and whether moisture is on the room-facing glass, between panes, or on the lining.

Our roof-window leak and condensation guide covers the water-related symptoms in more detail. Do not assume an external flashing repair will address an air leak at the sash, or that replacing a gasket will resolve staining from the roof around the window.

Do not climb onto the roof without proper safety equipment and safe access. Exterior window, flashing and roof-covering checks should be arranged professionally.

What should a draught-repair quotation include?

A useful quotation identifies the fault being addressed and the limits of the proposed work. Ask it to specify:

• The affected window and confirmed defect, with any unresolved possibilities noted.
• Parts, adjustment or installation-detail repairs included.
• Access arrangements and any internal lining removal or reinstatement.
• Whether surrounding roof weathering needs a separate inspection.
• How the result will be checked and what to report if discomfort continues.

A local repair may be appropriate where the window is otherwise sound. If broader deterioration is found, ask for the reasons behind a replacement recommendation and compare the complete scope. There is no reliable universal repair price without identifying the window, fault and access requirements.

Ask Perfect Roofing to assess a draughty roof window

Perfect Roofing helps with roof-window repairs, VELUX window work and surrounding roofing details in Dublin City, North Dublin, South Dublin, Lucan, Bray, Wicklow, Naas and nearby areas.

Send safe indoor photographs, your location, the window model if known, and a short description of where and when you feel cold air. We can discuss an assessment and a recommendation based on your roof, budget, weather exposure, access and long-term plans.

Message us on WhatsApp, call 083 066 3462, or email hi@perfectroofing.ie to arrange the next step.