WindowSkins are an attractive, affordable alternative to costly double glazing (window replacement) and traditional secondary glazing.
Whilst primarily designed for timber framed windows and doors, WindowSkins are also a practical secondary glazing solution for stone mullion windows.
This can significantly reduce problems related to Cold, Draught, Condensation and Noise.
Approved for Listed Buildings & Conservation Areas, WindowSkins can reduce heating costs and improve comfort.
Not just effective, the near-invisible design offers an unrivalled elegance and discreet aesthetic.
We offer a comprehensive measure, supply & professional fit service.
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Build Specification
Our magnetic Stone Mullion WindowSkins are typically built using 3mm Acrylic XT panels, paired with premium 13mm magnetic tapes.
Every WindowSkin is carefully crafted with exacting mitre joins in each corner, adhered with a premium foam backed TESA adhesive for long lasting use.
Precision laser measuring using our proprietary software solution ensures a perfect fit every time, even for irregular shaped windows.
The magnetic system creates an airtight seal, and is easily removed for venting and storage.
This significantly reduces the problems of Cold, Draught, Condensation and Noise.
Where noise is of primary concern, we can increase the panel thickness to 4mm.
Surface Preparation
Due to the inherent surface characteristics of Stone Mullion (unevenness, porosity and age related weathering), these prove to be one of the most technically difficult types of window to fit to.
As a result, significant surface preparation and finishing is usually required, as determined on a case-by-case basis. This significantly increases costs, when compared to equivalent fittings on regular casement and sash windows.
It should also be noted that due to the porosity of stone mullion and the variable condition of leaded lights, condensation performance may be slightly impaired (due to moisture ingress).
Stone Mullion WindowSkin installations benefit from an extended five year warranty.
For Stone Mullion Windows, There Are Two Possible Mounting Positions
Subframe Placement
(Standard Placement)
This is where a magnetised 13mm subframe is fit to the the side face of the stone mullion, within the window recess.
This is the more discreet option, as the WindowSkin sits flush within the window recess.
Subframes are typically used in situations where surface unsuitability prevents fitting in the Outer Placement (for Stone Mullion, this is more often the case).
The subframe design is unobtrusive and does not reduce visibility through the window.
Subframes can be constructed using PVC or wood for a longer lasting, premium finish
PVC Subframes are available in White or Teak, but can be painted or vinyl coated to a colour of your choice.
Click for more Stone ‘Subframe Placement’ image examples
(mounted in the ‘Subframe’ placement)
Outer Placement
(mounted in the ‘Outer’ placement)
This is where magnetic strips are attached to the front surface of the stone mullion, nearest the inside edge.
Assuming available space and a suitable surface, this is the least complex fitting.
The minimum space required for optimal fitting is 18mm and should be clear of obstructions.
Stonework should (ideally) be firm, in good repair and contiguous, with no large breaks.
The Outer Placement is the optimal position for noise reduction as the gap between glass and panel and total coverage is maximised.
Click for more Stone ‘Outer Placement’ image examples
Both Outer Placement & Subframe Placement provide excellent thermal efficacy, as they prevent draught as well as cold.
Panel Layout
For stone windows, as standard, we always mirror the mullion layout.
In the image example above, assuming we are fitting using the ‘Outer’ placement, this would be equivalent to four individual WindowSkins.
This standard layout offers maximum utility for removal, venting and storage and, most importantly, maximises the ratio of magnetism/adhesion versus panel surface area.
It should be noted that for stone mullion windows, we do not merge panels due to potential magnetism impairment and the surface limitations aforementioned.
Timber Subframes
Our standard subframes are manufactured using a lightweight extruded PVC.
Well suited for timber framed windows and doors, extruded PVC provides an optimal balance of strength and durability versus cost.
However, where stone mullion is concerned and, given the additional surface preparation and finishing requirements, there is good reason to switch to wood.
As well as it’s appealing natural beauty and distinctive warm textures, quality timber offers exceptional dimension stability and strength that will last many decades.
Whilst we are able to supply and fit wood subframes, depending on the location, it may be cost effective to have these constructed and fitted by a local joiner (subject to an agreed specification).
We recommend timber subframes are made using Accoya or a quality hardwood such as Oak.
All our timber subframes are fabricated in our own workshop, thereby minimising disruption during fitting.
Click for more timber subframe image examples
(with painted timber subframes)
Bespoke Split Panels
For larger windows, it is also possible to construct the WindowSkin into multiple sections.
This overcomes practical problems related to transport, handling and accessibility for very large windows, such as this circular WindowSkin fitted to a converted church gable window.
When in place, the panels are designed to butt together so they form one continuous panel, with each section being magnetically sealed around it’s perimeter.
For windows without sectional transoms, panels are instead joined using floating magnetic connectors, as illustrated in the image below.
Additional Considerations
The remaining aspects of Stone Mullion WindowSkins share the same characteristics as for Casement Windows.
Click on the subheadings above to read about those common features (opens in a new tab).
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