These Are The Most Common Mistakes People Do With Secondary Glazing Fitting

· 6 min read
These Are The Most Common Mistakes People Do With Secondary Glazing Fitting

Secondary Glazing Fitting: A Complete Guide to Enhanced Insulation and Soundproofing

The pursuit of a more energy-efficient and quieter home frequently leads home owners to consider different window treatments. While full window replacement is a typical service, it is not always possible-- specifically in heritage structures, preservation areas, or for those working within a particular budget plan. Secondary glazing provides a sophisticated, non-intrusive option. This guide explores the intricacies of secondary glazing fitting, the kinds of systems readily available, and the technical considerations required for an effective installation.

Understanding Secondary Glazing

Secondary glazing involves the setup of a supplementary window pane and frame on the interior side of existing primary windows. Unlike double glazing, where 2 panes of glass are sealed into a single system, secondary glazing creates a permanent or semi-permanent internal barrier. This configuration leaves the original external window unblemished, maintaining the architectural integrity of the structure while supplying contemporary thermal and acoustic benefits.

The Primary Benefits of Fitting Secondary Glazing

The choice to install secondary glazing is typically driven by 4 crucial factors:

  1. Thermal Insulation: It creates an insulating layer of air in between the primary and secondary glass, considerably lowering heat loss and reducing energy expenses.
  2. Acoustic Reduction: For residential or commercial properties located near busy roadways, airports, or rail lines, secondary glazing is frequently remarkable to standard double glazing for noise dampening. A broader air space (generally 100mm to 150mm) serves as an effective sound buffer.
  3. Condensation Control: By offering an internal seal, it avoids warm, damp indoor air from reaching the cold surface of the external glass.
  4. Heritage Compliance: Because the external look of the structure remains the same, it is the favored choice for Grade I and Grade II noted buildings.

Selecting the Right System

Before the fitting process starts, house owners need to pick a configuration that matches the performance of their existing windows.

Table 1: Secondary Glazing System Types and Applications

System TypeFinest Used ForPerformance
Horizontal SliderLarge casement windowsPanels slide side-to-side on tracks.
Vertical SliderTraditional sash windowsPanels go up and down, frequently balanced with springs.
Hinged UnitHigh-access areasOpens inward like a door; offers complete access to the main window.
Lift-Out UnitOccasionally opened windowsThe entire pane is eliminated manually for cleaning or maintenance.
Fixed UnitNon-opening windowsCompletely fixed for maximum insulation where ventilation isn't required.

Preparation and Measurements

The success of a secondary glazing fitting is greatly depending on the precision of the initial measurements. Because walls are hardly ever completely square, installers must measure the height and width of the window expose at three different points: the top, middle, and bottom (for width), and the left, center, and right (for height).

Essential Tools for Fitting

To make sure a professional surface, the following tools are generally required:

  • Digital laser measure or steel measuring tape.
  • Spirit level.
  • Power drill and numerous drill bits.
  • Premium silicone sealant and caulking gun.
  • Shim spacers (for leveling the frame).
  • Cleaning up products (microfiber cloths and glass cleaner).

The Fitting Process: Step-by-Step

The setup procedure generally follows a structured methodology to make sure the system is airtight and safe and secure.

1. Surveying the Reveal

The "expose" is the internal recess of the window opening. Installers must choose in between Face Fixing (fitting the frame straight onto the wall/architrave surrounding the window) or Reveal Fixing (fitting the frame inside the window recess, perpendicular to the glass). Expose fixing is normally chosen for much better acoustic performance as it enables a bigger air gap.

2. Preparing the Primary Window

Before the secondary unit is set up, the original window must be thoroughly cleaned and any practical concerns (such as rot or damaged latches) dealt with. When the secondary glazing is in place, access to the outer glass ends up being harder.

3. Assembling and Positioning the Sub-frame

Most modern-day systems use an external lumber or aluminum sub-frame. This sub-frame is placed within the reveal. Using a spirit level is vital at this phase; if the sub-frame is even slightly tilted, sliding panels may not move smoothly or seals might stop working to fulfill correctly.

4. Protecting the Frame

When leveled, the frame is pilot-drilled and screwed into the masonry or timber surround. Installers use shims or packers to fill any gaps between the frame and the wall, ensuring the unit sits completely square no matter the wall's disparities.

5. Sealing for Performance

To achieve the promised thermal and acoustic advantages, the perimeter of the frame should be sealed. An acoustic-grade sealant is used to the space between the sub-frame and the wall. This avoids "air leak," which is the primary reason for heat loss and sound infiltration.

6. Setting Up the Glazed Panels

The glass panels are then clipped or moved into the frame. For sliding systems, this involves positioning the top of the panel into the upper track and after that dropping the bottom into the lower track. For hinged systems, the panels are hung on top quality hinges and changed for a flush fit.


Comparing Secondary Glazing to Replacement Windows

Residential or commercial property owners frequently weigh the expenses and advantages of secondary glazing versus full window replacement (double or triple glazing).

Table 2: Comparison of Secondary Glazing vs. New Double Glazing

FeatureSecondary GlazingNew Double Glazing
Typical CostLower (approx. 30-50% less)Higher (full frame and glass replacement)
Noise ReductionExcellent (up to 80% decrease)Good (but limited by narrow air gaps)
Installation ImpactVery little (no structural changes)Significant (needs removal of old frames)
Aesthetic ImpactPreserves original exteriorChanges external appearance
Thermal EfficiencyConsiderable improvementOptimized (especially with triple glazing)
MaintenanceLowLow to Moderate

Expert vs. DIY Fitting

While secondary glazing packages are offered for DIY lovers, professional fitting is often suggested for several factors. Professional installers have the knowledge to manage large panes of toughened glass safely and can ensure an airtight seal that a novice might miss out on. Additionally, personalized units produced to the millimeter use a significantly cleaner visual than standard off-the-shelf plastic magnetic strips.

Upkeep Recommendations

As soon as fitted, secondary glazing needs really little maintenance. The following regimen is recommended:

  • Cleaning: Use a mild detergent and soft fabric. Prevent abrasive chemicals that could damage powder-coated aluminum frames.
  • Lubrication: For sliding systems, occasionally apply a silicone-based lubricant to the tracks to guarantee smooth operation.
  • Seal Inspection: Once a year, examine the border sealant for any fractures or peeling to preserve thermal stability.

Frequently Asked Questions (FAQ)

Can secondary glazing be fitted to uPVC windows?

Yes. While it is most typical on lumber or metal windows in older homes, it can be fitted to uPVC windows to even more enhance soundproofing, especially if the property is near a noise source that the existing uPVC can not deal with alone.

Just how much of an air space is required for soundproofing?

For maximum acoustic performance, a space of 100mm to 150mm in between the primary and secondary glass is advised. If  blandford forum secondary glazing windows  is too small (less than 50mm), the soundproofing benefits are considerably decreased.

Will secondary glazing stop condensation completely?

For the most part, yes. By creating a seal that avoids warm air from hitting the cold outer pane, condensation is drastically minimized. Nevertheless, it is necessary that the primary window remains somewhat "breathable" to enable any trapped wetness in between the panes to escape, or that the unit consists of desiccants.

Is preparing permission required?

Normally, no. Because secondary glazing is an internal modification and does not alter the exterior of the property, it normally falls under "allowed advancement." Nevertheless, occupants of Grade I noted structures should constantly consult their regional preparation authority initially.

Does it make the windows more difficult to clean up?

Due to the fact that many secondary glazing systems are developed to move, hinge open, or be lifted out, accessing the initial window for cleansing stays relatively simple.


Secondary glazing fitting is an extremely efficient, non-invasive approach for upgrading the performance of existing windows. By concentrating on accuracy measurement and airtight sealing, property owners can achieve a substantial decrease in sound pollution and an obvious increase in thermal comfort. Whether the objective is to maintain the beauty of a period home or to find peace and peaceful in a bustling city apartment, a correctly fitted secondary glazing system stands as one of the most cost-efficient home improvements readily available.