T-Vault GRP barrel vault

T-Vaults are high performance continuous barrel vault rooflights designed to provide a functional, economical rooflight for roof spans up to 4m and of unlimited length.

These continuous rooflights are suitable for both new and refurbishment applications and come in a range of glazing and ventilation options.  T-Vault flat roof windows are suitable for flat roofs including single ply, felt, hot-melt, asphalt, liquid, GRP and lead. They are also deemed a non-fragile rooflight in accordance with (HSE) Health and Safety in Roofworks.

T-Vault continuous barrel vault rooflights are constructed from a series of interlocking curved and profiled GRP (glass reinforced polyester) panels.   T-Vault skylights have a high light transmittance and an outer protective Melinex® film providing guaranteed protection against UV degradation.  These durable roof lights have an extremely high level of resistance to weather erosion and chemical influences and are also suited to industrial conditions.

  • Available in unlimited lengths
  • Economical option
  • Profiled GRP outer skin
  • Profiled GRP inner skin
  • Insulated end panel
  • Z-Plate fixing
  • Profiled foam seal

Profiles and sizes

T-Vaults are purpose-made and available in one standard profile and widths from 1.0m to 4.0m and in unlimited length.


T-Vaults are available in single, double or triple skin versions. The barrel vault is made up of a series of curved and interlocking profiled GRP sheets.  The sheets are 1070mm wide and have a bending radius of 3150mm.

All outer sheets are supplied in Longlife GRP which are UV stabilised and finished with a protective film that provides an extremely high level of UV stabilisation to maintain transparency and prevent ageing.

Available options:
  • GRP Single skin
  • GRP Double skin
  • GRP Triple skin

Barrel vaults are also available with polycarbonate glazing – our Em-Vault range.  Click here for more details.


T-Vault glazing is available in the following finishes:

  • Clear
  • Opal Diffused
  • HeatReflect
  • Bronze
Glazing Specification Table
Glazing Light transmission (LT %)* Solar heat gain factor (g %) Thermal transmission (W/m²K)
GRP Single Clear 87% 77% 5.74
GRP Single Opal Diffused 63% 47% 5.74
GRP Single HeatReflect 86% 45% 5.74
GRP Double Clear 76% 67% 3.13
GRP Double Opal Diffused 54% 41% 3.13
GRP Double HeatReflect 66% 39% 3.13
GRP Triple Clear 66% 58% 2.16
GRP Triple Opal Diffused 48% 36% 2.16
GRP Triple HeatReflect 57% 34% 2.16

*Thermal transmission refers to U-Values.  For Ud-Values, please contact us.


The T-Vault is normally specified with our uPVC Em-Curbs but can be fixed directly to a splayed top builder’s upstand, which can be made of timber, concrete or metal. Dead and imposed loadings plus lateral thrust calculations can be calculated according to the continuous rooflight technical data.

  • Builder’s upstand
  • Em-Curb ECO uPVC 300mm Splayed
  • Em-Curb ECO uPVC 350mm Oversleeve Splayed

For more information on Em-Curbs, visit the Em-Curb page.

Curb angle

On the long sides the curb top should be splayed as noted in the table below. Curbs at each end of the rooflight should be horizontal.

Span (m) 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Angle 10° 15° 20° 25° 30° 35° 40°


All T-Vaults have fixed glazing as standard.  However, the options listed below can be incorporated in most permutations of T-Vault installations.

Permanent Trickle

Permanent background ventilation is made possible with space plates. This provides a continuous weatherproof vent around the perimeter of the rooflight which suits areas such as corridors and storage where non-controllable background ventilation is required.

Controllable Rotating

Controllable rotating vents are a fully insulated unit with enhanced thermal properties.  With the vents on two sides, the unit will provide a minimum of 11,000mm2 ventilation area. This increases with the length of the rooflight.

For more detailed information on each of the available ventilation types, visit the Em-Dome Ventilation page.


Fire tests have been carried out and the units are certified according to EN1187.  T-Vaults use a glass reinforced polyester (GRP) glazing and have been tested and certified according to EN 14963: 2006 – Non-Fragile and ACR(M): 001: 2005 Class B.

Typical values Standard Fire retardant
Fire rating to BS 476: Part 3 AB AA
Fire rating to BS 476: Part 7 Class 3 Class 1
Service temperature -50 to +120°C -50 to +120°C
Resistance to wind load Class 2 Class 2
Air permeability Class 2 Class 2
Resistance to water penetration Class 9a Class 9a
Impact test 1200 J 1200 J
Wind driven rain/snow 600Pa Pass Pass

T-Vaults have been tested with Vertical and Horizontal forces to enable reliable performance.


The system has a very high resistance against chemical influences and weather conditions and carries a 20 year hailproof guarantee.  All T-Vault barrel vault rooflights are guaranteed for a period of ten years.  For further information, extended guarantees, or specific project guarantees contact us.

Installation Instructions


The sheets are installed with corrosion resistant fixings located centrally between crowns. All fixings and synthetic foam fillers are included as well as the mounting accessories for the end panels.

The Z-Fixing system ensures that the inner and outer skins are kept a constant distance apart.

We recommend using out installation service for our more complex continuous and bespoke products. Please contact us for more information.

Operation and maintenance

Whitesales skylights, rooflights and accessories can generally be regarded as ‘maintenance free’. However, the following guidelines should be followed to optimize their usefulness. Any maintenance of rooflights must of course be carried out strictly in accordance with the relevant ‘Health and Safety’ regulations.


T-Vaults are fixed at installation stage to the relevant upstand, and are a means of allowing natural light into the area below. T-Vaults can be supplied as ‘Non-Fragile’, but should not be trafficked.
Wash only with warm soapy water. DO NOT USE strong detergents or abrasives.
Physically check Barrel Vaults annually to ensure fixings are secure.

Contact us and
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