Winsul8 Technology - Insulated Core System

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Winsul8 Technology. Quick stats.

Not only does our brand NEW GFRC Insulated Core Door & Window System produce some of the most thermally efficient door & window products available, surpassing current UK building regulations, but they also have some other impressive statistics too! Here are just a few ...


w/m2k - U-value

U-value as low as 1.03w/m2k for triple glazed + 1.37w/m2k for double glazed products.


Gasket line

5mm gasket line between sashes (one piece gasket - no trimming around hinges).


Material options

Aluminium (Flush), Aluminium / Glass, Aluminium / Timber, Flush Glass / Glass, Timber / Glass, Hardwood Timber


Winsul8 Systems

Classic range available Spring 2023 and Signature range Summer 2023.

Winsul8 Technology. Great features.

Key Features

• Two brand NEW thermally efficient door & window systems; CLASSIC + SIGNATURE

• New GFRC Insulated Core System - Glass Fibre Reinforced Composite Thermal Breaks

• Foam filled frames + track cavities

• Lift on security hinges

• Fast fit, screw locked glazing beads (includes thermal break)

• Stronger aluminium construction - Corner cleat + wedge pins

• Slimmer sight line - 110mm

• 5mm gasket line

• Surround trim (inside / outside), built in fitting tolerance / gasket housing, custom accent colour available

• One continuous piece compression gaskets

• Pivotable rollers

Thermal Efficiency

• U-values as low as 1.03 w/m2k (triple glazed)

• U-values as low as 1.37 w/m2k (double glazed), emissivity options of 1%, 3%, 5% and 10%

• Improved, warmer larger thermal insulation break within profiles & tracks (Winsul8 Technology)

• Foam filled frames - Upgrade for improved thermal efficiency / better U-value @15%

• Fast fit glazing beads, built-in thermal break included

• Low-E glass units, includes Super Spacer® bars (non thermal bridging)

• Argon gas filled glazing units

• Surpasses Part L 2002 Compliant (UK Building regulations)

• CE Compliant

• Thermally simulated test results


• External rebates; exterior top and bottom (includes gaskets) for increased weathering properties

• Interior rebates (includes gaskets); top (as standard), bottom (optional, opening style dependent).

• Exterior rebates; top and bottom.

• We use 2 continuous rubber EPDM compression gaskets on each side of each panel (not cut around the hinges)

• High performance seals on the top and bottom of each panel

• Bi-fold range includes a tongue and groove feature which prevents water infiltration

• CE compliant

• High performance rubber compression seals

• Weather rated flush track / threshold

• PAS23 - pending


• Anti-lift hinges (inc. grub screw)

• Stronger aluminium sash construction

• Screw locked glazing beads

• Secured by Design (SBD) 3 star ABS TS007 euro cylinders - anti-snap, anti-pick, anti-bump, anti-drill

• Multi-point Locking (PAS24)

• Internal lockable handles

• Internally glazed

•  Laminated glass optional

• Document Q Approved* PAS 24:2012

• Encapsulated rollers

• Interlocking panels

Colour Options

• 3x stock colours; Traffic White, RAL 9016 (Satin Finish), Anthracite Grey, RAL 7016 (Matt Finish), Jet Black, RAL 9005 (Matt Finish)

• Any RAL / Any special finish / Dual colour

• Accent trim colour (any RAL) on Signature range

• Hardware; Standard colour options; black, white, chrome, anthracite grey, satin nickel and stainless steel
Colour matched to profile colour

Finishes & coatings

• Aluminium; Powder coated (Classic)

• Aluminium; Powder coated / Marine coated / Anodised / Any special finish

• Glass; Any RAL (silk screen printed glass from the reverse)

• Hardwood Timber; Natural translucent stains / Any RAL (sprayed) / Unfinished

Glass options

• Double Glazed (inc. super spacer bar), low e coated tempered (toughened) clear units

• Triple Glazed  (inc. super spacer bars x2), low e coated tempered (toughened) clear units

• Laminated Glass

• Anti-sun tinting (grey, bronze, green and blue)

• Turtle Glass

Glazing options

• Transoms / Mullions

• Georgian Bar (Internal), applied internally to glazing

• Integral Blinds

• Leaded Glass

• Unglazed

• Deep bottom rail (timber option)

9x Threshold options

• Flush Track (Approved Document M - Disability access)
• Flush Track with Rebate
• Flush Track with Cill
• Flush Track with Cill and Rebate

• Raised Track
• Raised Track with Rebate
• Raised Track with Cill
• Raised Track with Cill and Rebate
• Raised Track with Double Cill (Available with or without Rebate)

All include WINSUL8 technology


Available products

Bi-fold, Sliding, Corner, Residential & French Doors, Bi-fold & Flush Casement Windows.


mm - sight line

Slimmer sight lines, now 110mm between glazing; profile + 5mm gasket + profile.


mm systems

Both WInsul8 systems are a traditional 70mm front to back (deep) dimension.


Threshold options

Flush & Raised Tracks (+ Rebate, + Cill, + Cill & Rebate), Raised Track with Double Cill (+ Rebate).


Request General Arrangement Drawings.

We can supply pdf and dxf file formats (please request) to assist your architect should you need them, please email This email address is being protected from spambots. You need JavaScript enabled to view it.

Frequently Asked Questions

Find answers to commonly asked questions here

Yes, FSDC Global are actually introducing two completely new door & window systems for 2023; the 'Classic' range will be available from Spring and the 'Signature' range to follow in the summer.

Directly in response to the UK Government announcements to the help the UK deliver net zero, and in particular in relation to the new UK Building regulations Part L (conservation of fuel and power) and the tightening of U-values.
Doors and windows will need to have vastly improved thermal efficiency ratings, which means lower U-values (lower the number, better the thermal efficiency), which overall means less energy is required to heat or cool a home.
To achieve this we needed to make some improvements, resulting in two new fantastic thermally efficient systems.

In a nut shell, lower energy bills, and a more comfortable environment to live in, whichever system you choose. Oh, and not forgetting great looking products utilising the latest modern technology in insulation.
You can also hold your head up high because you are choosing the most thermally efficient doors and windows available for your home which in turn is kind to the environment, your pocket and our planet.

As of 15th June 2022, the minimum U-values for windows and roof lights for existing dwellings has improved from 1.6 to 1.4 W/m²K and doors from 1.8 to 1.4 W/m²K. Additional to this, the notional standard (SAP10 Standard Assessment Procedure) suggests a lower U-value of 1.2 W/m²K, which may be an indication of standards to come. Both our new systems can achieve 1.03 W/m²K using triple glazed units and 1.37 W/m²K using double glazed units.

Through a combination of design improvements, five to be exact! Both our systems; Classic and Signature (inc. our current systems) include thermal insulation breaks within the profile, whereby cold (or heat) cannot transfer across from the inside to outside and vice versa (thermal bridging). Our two new systems have re-designed profiles [1] and utilise ‘Winsul8 Technology’ [2], which is our new Insulated core system. The new profile allows us to accommodate larger and additional thermal insulation breaks (Winsul8 Technology) both within the profiles and tracks themselves. We also changed the material of the thermal break from polyurethane to GFRC (Glass Fibre Reinforced Composite) material [3], which offers substantially better insulating properties, as well as strength. We also incorporate a thermal break on our glazing clips [4] as standard and offer the inclusion of foam filled frames [5] which can increase thermally efficiency by as much as 15%.

Both the Classic system and Signature system incorporate the same improvements; profile re-design and include ‘Winsul8 Technology’ our new Insulated core system, which make them very similar in that respect.
There are a few differences that set them apart; the Classic range uses our existing track options and is only available in aluminium in the 3 stock colour options (though you can spec up an order). It also has a 15mm (finger safe) gasket line between panels.
The Signature system includes our new improved thermally efficient track and is available in a huge choice of material options; Aluminium (Flush), Aluminium / Glass, Aluminium / Hardwood Timber, Glass / GlassIIEdge™ (flush),  Hardwood Timber / GlassIIEdge™ (flush), Hardwood Timber. You can specify any colour, RAL colour, finish and these come with the option to add a custom accent colour to the aluminium surround trim (inside / outside). This system has a 5mm gasket line between panels and built-in fitting tolerance.

Both systems offer the same product range; bi-fold doors, sliding doors, corner doors, french doors, bi-fold windows and flush casement windows. It’s only the material options that set them apart.

Thermal transmittance, also known as U-value, is the rate of transfer of heat through a structure (which can be a single material or a composite), divided by the difference in temperature across that structure.  The units of measurement are W/m²K.
W/m2K stands for Watts-per- meter-square-kelvin. The lower this value, the better a product is at insulating a building.

You can visit our Winsul8 web pages, call +44 (0) 345 64 64 646 (UK) / +1 786 275 5068 (USA) or email This email address is being protected from spambots. You need JavaScript enabled to view it.