News & Insights

Condensation on windows is one of the most common concerns homeowners raise, and one of the most misunderstood. It can appear on the inside of the glass, on the outside, or between the panes. Each type has a different cause, a different implication, and a different solution. Treating them all the same leads to frustration, unnecessary expense, and in some cases, ignoring the one type that actually does indicate a problem.

Internal condensation

Condensation on the inside surface of the glass is the most common type. It forms when warm, moist indoor air comes into contact with a glass surface that is cooler than the dew point of the air. The moisture in the air changes from a gas to a liquid, and water droplets appear on the glass. It is the same process that causes a cold glass to “sweat” on a warm day.

This is not a fault with the window. It is a sign that the humidity level inside the home is high relative to the surface temperature of the glass. It is most common in kitchens and bathrooms where cooking, showering, and boiling water produce large amounts of moisture, and in bedrooms overnight where breathing and reduced ventilation allow humidity to build up.

The solution is a combination of ventilation and glazing performance. Opening windows, using extractor fans, and keeping trickle vents open all help remove moisture-laden air before it has a chance to condense. On the glazing side, windows with lower U-values keep the internal glass surface warmer, which reduces the likelihood of condensation forming. Triple glazing outperforms double glazing in this regard because the inner pane stays closer to room temperature. Warm-edge spacer bars also play an important role by reducing heat loss at the glass perimeter, which is where condensation typically appears first.

External condensation

Condensation on the outside of the glass surprises many homeowners, particularly those who have recently upgraded to high-performance windows. It appears as a fine mist or water film on the exterior surface, usually in the early morning, and it clears as the temperature rises.

This is actually a sign that your windows are performing well. It occurs because the outer pane of a highly insulated glazing unit stays cool, since very little heat is escaping through the glass from inside. When the outside air temperature drops overnight and humidity is high, moisture condenses on that cool outer surface in the same way that dew forms on a car windscreen.

External condensation requires no action. It is a natural consequence of good thermal performance and will clear on its own as conditions change. It is worth understanding this before contacting your supplier, as it is often mistakenly reported as a defect.

Condensation between the panes

This is the one type of condensation that does indicate a genuine problem. If moisture appears inside the sealed unit, between the two or three panes of glass, the seal around the edge of the unit has failed. The inert gas fill has escaped and moist air has entered the cavity. Once this happens, the unit has lost a significant portion of its insulating performance, and the condensation will not clear.

A failed sealed unit cannot be repaired. The glazing unit needs to be replaced. On modern windows, this is usually a straightforward process where the sealed unit is swapped within the existing frame, without removing or replacing the window itself. However, it should be addressed promptly. A failed unit contributes to increased heat loss, persistent moisture on the glass, and in some cases mould growth around the window reveal.

Common myths

Several misconceptions about condensation persist and are worth correcting.

The first is that new windows cause condensation. In reality, new windows are more airtight than the old ones they replace. Older windows with gaps and worn seals provided uncontrolled ventilation that carried moisture out of the home, even though they also let heat escape. When those gaps are eliminated by well-sealed modern windows, the moisture that was previously escaping now stays inside the room. The solution is not to make the windows less airtight. It is to ventilate properly using trickle vents, extractor fans, and good ventilation habits.

The second is that condensation means the windows are faulty. As outlined above, internal and external condensation are not defects. Only condensation between the panes indicates a failed unit.

The third is that opening a window in winter wastes energy. Brief, focused ventilation, such as opening a window fully for five to ten minutes, is far more effective at removing moisture than leaving a window slightly open for hours. It exchanges the moist air quickly without allowing the walls, floors, and furniture to cool down significantly.

Reducing condensation in your home

Managing condensation effectively comes down to two things: controlling indoor humidity and ensuring the glass surface temperature stays as high as possible. Ventilate high-moisture rooms during and after cooking, showering, and drying clothes. Keep trickle vents open. Use extractor fans where fitted. And if your glazing is old or underperforming, upgrading to modern units with low U-values and warm-edge spacer technology addresses the root cause by keeping the glass warmer.

If you are experiencing persistent condensation issues and are unsure whether the cause is ventilation, glazing performance, or a failed sealed unit, book a free consultation with the Fairco team. We can assess the situation and recommend the right solution for your home.

Autumn is when the performance of your windows and doors starts to matter most. As temperatures drop, winds pick up, and rain becomes a near-daily feature, any weakness in the building envelope becomes noticeable. Draughts that were easy to ignore in summer become uncomfortable. Condensation appears on glass that stayed clear for months. Doors that closed easily start to feel stiff or loose. Taking the time to check your windows and doors before winter sets in can make the difference between a comfortable season and one spent fighting the cold.

Check your seals

The rubber gaskets and weather seals around your window and door frames are the first line of defence against draughts and water ingress. Over time, these seals can compress, harden, crack, or pull away from the frame, allowing air and moisture to find a way through. Run your hand slowly around the perimeter of each closed window and door. If you can feel cold air moving through, the seal is no longer doing its job.

On newer windows, worn seals can often be replaced without replacing the entire unit. On older windows where the seal has degraded significantly, or where the frame itself has warped or moved, replacement may be the more effective solution. If you are unsure, a professional assessment can clarify which approach makes sense.

Test your hardware

Locking mechanisms, handles, hinges, and friction stays all need to operate smoothly for the window to close fully and seal properly. A handle that does not engage the multi-point locking system completely, or a hinge that has dropped slightly, can leave the sash sitting fractionally out of alignment. This is enough to break the seal compression and allow draughts through, even if the window appears closed.

Open and close each window and door fully, testing the handle action and checking that the locking points engage without force. If anything feels stiff, loose, or misaligned, it may need adjusting or replacing before the colder months. Fairco customers can book a service appointment if their windows or doors need attention.

Clear the drainage

All modern windows and doors have drainage slots or channels designed to allow any water that enters the frame to escape to the outside. These slots can become blocked with dirt, leaves, or debris, particularly after summer. If the drainage is obstructed, water can build up inside the frame, potentially causing damage to the seals, the hardware, or the internal reveals. A quick check and clean of the drainage channels on the bottom of each frame is one of the simplest and most effective pieces of maintenance you can do before winter.

Look at the glass

If condensation is forming between the panes of a double or triple glazed unit, the sealed unit has failed. The gas fill has escaped and moisture has entered the cavity, reducing the thermal performance of the glazing significantly. A failed sealed unit cannot be repaired. It needs to be replaced. This is a relatively straightforward job on modern windows where the glazing unit can be swapped without replacing the frame, but it is important to address it before winter, as a failed unit will contribute to heat loss and further condensation problems.

Condensation on the inside surface of the glass is a different issue. It is caused by warm, moist indoor air meeting a cold glass surface, and it is more common in kitchens and bathrooms where humidity levels are higher. Improving ventilation, using trickle vents, and upgrading to glazing with a lower U-value and warm-edge spacer bars all help reduce internal condensation.

When maintenance is not enough

There comes a point where maintenance on ageing windows and doors no longer delivers meaningful results. If you are dealing with persistent draughts despite new seals, visible frame distortion or warping, multiple failed glazing units, hardware that no longer locks securely, or condensation that returns no matter how much you ventilate, the windows have reached the end of their effective service life. Continuing to patch them is spending money on a diminishing return.

Replacing old windows with modern, high-performance units delivers an immediate improvement in comfort, energy efficiency, security, and appearance. It also has a direct impact on your BER rating and may qualify for the SEAI windows and doors grant, which helps offset the investment.

Get ahead of winter

The best time to address window and door issues is before you need them to perform at their best. Autumn gives you the window to assess, maintain, or replace before the worst of the weather arrives. If you have been putting off an upgrade, acting now means you benefit from improved comfort and lower energy bills throughout the entire heating season rather than starting it at a disadvantage.

Book a free consultation with the Fairco team, or visit our showrooms to explore your options before winter sets in.

Few window configurations have as much architectural impact as a bay or bow. They change the shape of a room, increase natural light from multiple angles, and add a sense of depth and character to the exterior of a property that flat windows simply cannot achieve. Whether you are restoring a Victorian or Edwardian home where bays are a defining feature, or introducing one into a new build or extension for the first time, understanding the difference between the two styles and what goes into specifying them well is worth the time.

Bay vs bow: what is the difference?

The terms are often used interchangeably, but they describe two distinct configurations. A bay window projects outward from the face of the building at defined angles, typically forming three flat sides. The most common arrangement is a wide front panel flanked by two narrower side panels set at 30, 45, or 90 degrees. The angles are sharp and the lines are straight, giving the window a structured, geometric appearance. Bay windows are a hallmark of Victorian and Edwardian architecture and remain one of the most recognisable features of period homes across Dublin and Ireland.

A bow window also projects from the wall, but it uses a series of panels set at gentle, incremental angles to create a curved profile. The curve is typically formed from four or five individual units joined together, and the effect is softer and more fluid than a bay. Bow windows suit Georgian townhouses, where the proportions tend to be more restrained, and they also work well in contemporary designs where a subtle curve adds visual interest without the angular drama of a traditional bay.

What they do for a room

The practical benefit of a bay or bow window is that it captures light from three or more directions rather than just one. In a north-facing room or a narrow terrace where light is limited, this makes a noticeable difference to how bright and open the space feels. The projection also creates additional floor area inside, which is often used as a reading nook, a window seat, or simply extra room that would not otherwise exist.

From the outside, a bay or bow window breaks up a flat facade and gives the property a sense of depth and proportion. On a terraced street, a well-detailed bay window can be the single feature that distinguishes one home from its neighbours. On a detached property, it adds scale and visual weight to the front or side elevation.

Materials and detailing

Bay and bow windows can be built in any of Fairco’s frame materials. For period properties, sash windows configured as a bay are the most architecturally faithful option. A Heritage Sash bay with run-through horns, slim meeting rails, and a traditional colour finish brings the window back to its original character while delivering fully modern thermal and security performance.

Performance uPVC and OMNIA Flush suit more contemporary bay configurations, where the clean lines of a flush profile and a modern colour palette complement the geometry of the projection. For larger bays where maximum glass area and minimal frame are the priority, aluminium offers the slimmest sightlines and the structural strength to span wider panels without heavy framing.

The joining detail between panels is important in any bay or bow. The mullion profiles, the corner posts, and the way the units are coupled together all affect both the appearance and the weather performance of the assembly. Because Fairco manufactures in-house, these junctions can be engineered precisely to suit the angles and dimensions of each project.

Practical considerations

Bay and bow windows are heavier than flat window configurations and place additional load on the structure below. In new builds, the supporting structure is designed around the window from the start. In renovations or replacements, it is important to assess the condition of the existing bay structure, including the lintel, the bay cheeks, and the base or corbel supporting the projection. If you are replacing the windows in an existing bay, the new units may differ in weight from the originals, particularly if upgrading from single or early double glazing to triple glazing, so the supporting structure should be reviewed as part of the survey.

In some cases, planning permission may be required, particularly if the bay involves a change to the external profile of the building or if the property is in a conservation area. Like-for-like replacement of existing bay windows is typically exempt, but it is always worth confirming before work begins.

A window worth getting right

Bay and bow windows are among the most visible and character-defining features on any home. Getting the proportions, the detailing, and the material choice right makes the difference between a window that looks like it belongs and one that feels like an afterthought. Because every bay and bow is a bespoke configuration, early consultation with your supplier ensures the design, structural requirements, and installation approach are all aligned before manufacturing begins.

Book a free consultation with the Fairco team to discuss your bay or bow window project, or visit our showrooms to see the range of materials and finishes available.

When you choose new windows and doors, you are trusting that they will perform as promised for decades. They need to keep heat in, keep weather out, resist forced entry, and operate smoothly year after year. But how do manufacturers prove that a product can actually do all of these things? The answer lies in a series of rigorous, independently verified tests that every product must pass before it can be installed in your home. Understanding what these tests involve gives you a clearer picture of what you are actually paying for when you invest in quality.

Weather performance testing

Weather performance is assessed under EN 14351-1, the European product standard for windows and doors. Three properties are measured, each on a classified scale.

Air permeability measures how much air leaks through the window or door when it is closed. The product is mounted in a test rig and subjected to increasing air pressure. The amount of air that passes through the frame, seals, and junctions is recorded at each stage. A higher classification means less air leakage, which translates directly to fewer draughts and lower heating costs in your home.

Water tightness measures how well the product resists water penetration under pressure. Water is sprayed against the external face of the window while air pressure is applied to simulate wind-driven rain. The test increases in intensity until water penetrates the assembly. For coastal and exposed properties, a higher water tightness classification is essential.

Wind resistance tests the structural integrity of the window under sustained wind loading. Positive and negative pressure cycles are applied to simulate the forces a window experiences during high winds. The product must maintain its structural integrity, and the deflection of the frame must remain within defined limits. This matters in Ireland’s climate, where winter storms regularly produce wind gusts that place significant pressure on the building envelope.

Security testing

PAS 24:2022 is the current enhanced security standard for windows and doors. It is a pass-or-fail test designed to replicate the methods an opportunist burglar would use to break into a home.

The testing sequence includes mechanical loading, where significant force is applied to the frame and hardware to test whether the window can be prised open. It includes hard and soft body impact, simulating blunt force strikes against the glass and frame. And it includes manual attack, where a tester uses a prescribed set of tools to attempt to manipulate hardware, cut through materials, and remove glazing. For doors, additional tests cover cylinder vulnerability and letterplate security.

Every Fairco window and door is independently certified to PAS 24:2022, which means every product in the range has been subjected to and passed this full testing regime.

Thermal performance testing

The thermal performance of a window is expressed as a U-value, measured in W/m²K. A lower number means less heat passes through the assembly. U-values are determined through a combination of laboratory testing and calculation, taking into account the glass, the gas fill, the spacer bar, the frame material, and the way these components interact at junctions.

Whole-window U-values are important because they reflect the performance of the complete assembly, not just the centre of the glass. The frame, the edge of glass, and the spacer bar all influence the final number. This is why products with warm-edge spacer bars, multi-chambered profiles, and triple glazing consistently outperform products that may have the same centre-pane glass but weaker detailing at the edges and frame.

Cycle testing

Windows and doors are opened and closed thousands of times over their lifetime. Cycle testing simulates this by operating the hardware repeatedly under controlled conditions, checking that handles, locking mechanisms, hinges, and friction stays continue to function correctly after extended use. This is particularly important for tilt-and-turn windows and multi-point locking systems, where the mechanism is more complex, and the long-term reliability of the hardware directly affects both security and ease of use.

From the laboratory to your home

Testing proves what a product can do under controlled conditions. But the results only hold true if the product that arrives at your home is built to the same specification as the one that was tested. This is where manufacturing quality and consistency become critical.

Because Fairco controls design, manufacture, and installation from our Antrim facility, the product installed in your home is built to the same tolerances, with the same components, and to the same specification as the product that passed every test. That chain of accountability is what separates a test certificate from real-world performance.

If you would like to understand more about how Fairco products are tested and certified, book a free consultation or visit our showrooms to see the quality of construction firsthand.

French doors have been a feature of residential architecture for centuries. Their appeal is enduring because the idea behind them is simple and effective: two full-height glazed doors that open together to create a wide, unobstructed connection between inside and outside. In a market where sliding doors and bi-fold doors often dominate the conversation, French doors continue to hold their own, and for good reason. They suit situations that other door types do not, and they bring a sense of proportion and character that is difficult to replicate with a different format.

When French doors are the right choice

French doors work best in openings where the width is moderate rather than expansive. Where a sliding or bi-fold door needs a wider span to justify its design, French doors are naturally suited to openings of around 1.2 to 1.8 metres. This makes them ideal for connecting a living room or kitchen to a patio, a bedroom to a balcony, or an internal room to a conservatory or extension.

Because both doors swing open fully, the entire width of the opening is clear when the doors are in use. There is no track to step over, no panel stacking to one side, and no mechanism to operate beyond a simple handle turn. This simplicity is part of their appeal. They are intuitive, reliable, and easy to maintain over a long service life.

French doors are also one of the few door types that can be configured to open either inward or outward, depending on the space available and the homeowner’s preference. Outward opening keeps the interior floor area clear, while inward opening can be preferable where external space is limited or where a flush threshold is required for accessibility.

Design versatility

One of the strengths of French doors is how comfortably they sit within different architectural styles. On a period property, a pair of French doors with astragal glazing bars and a heritage colour finish feels entirely at home. On a contemporary facade, a flush profile in anthracite grey or matt black delivers clean, modern lines. This adaptability is why French doors remain one of the most frequently specified door types for both renovations and new builds.

Pairing French doors with fixed sidelights or fanlights is a practical way to increase the overall glazed area without widening the opening itself. Sidelights add width and light while the door panels remain a manageable size and weight, keeping the hardware and hinges under less stress and ensuring smooth operation for years to come.

Fairco’s French doors are available in Performance uPVC, OMNIA Flush, and aluminium, meaning you can match them precisely to the windows elsewhere in the house. For homeowners specifying OMNIA Flush throughout, the French door shares the same flush profile and shadow line as the window range, maintaining complete design consistency across every opening.

Security and weather performance

A common concern with double-door configurations is security. Fairco French doors address this with a double rebated design, where the two doors interlock when closed, eliminating the gap between the panels that can be a weakness in lesser products. Multi-point locking systems, reinforced frames, and PAS 24:2022 certification ensure the doors meet the same security standard as every other product in the Fairco range.

Weather performance is equally important. French doors are exposed to the same wind-driven rain and pressure that affects any part of the building envelope. Fairco’s doors are tested for air permeability, water tightness, and wind resistance, with weather-tight seals and drainage routes designed to handle Ireland’s climate, including coastal and exposed locations.

Thermal performance

French doors are available with double or triple glazing and thermally efficient frames, delivering strong insulation without compromising the generous glazed area. Low-emissivity coatings, argon gas filling, and warm-edge spacer bars all contribute to a low U-value, reducing heat loss and supporting energy performance goals. Fairco French doors are rated A++ for energy efficiency as standard.

A door that fits your home

Every Fairco French door is made to order and tailored to your exact dimensions, finish, and glazing specification. Whether you are replacing an existing pair, adding a new opening in a renovation, or specifying for a new build, French doors offer a combination of elegance, practicality, and performance that few other door types can match.

Book a free consultation to discuss your project, or visit our showrooms to see Fairco French doors alongside the full window and door range.