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Isometric view on domed rooflight indicating required dimensions

Upstand Dimensions
(Intermediate Frameword Omitted)

 

Isometric view on single curved domed roof

Single Curved Dome
(Intermediate Frameword Omitted)

 

Isometric view on dual curved domed roof

Dual Curved Dome
(Intermediate Frameword Omitted)

 

Typical sections through a frameless glazing system

(Frameless Glazing)

 

Typical section through a structural glazing system

(Structural Glazing)

 

Typical section through a framed glazing system

(Framed Glazing)

 

Bespoke Domed Rooflight, Skylight and Atrium Designs

 
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Domed glass rooflights, skylights and atriums are a great effective way of introducing natural light through a roof opening, whilst producing multiple lines of symmetry and a single focal point. Glass dome rooflights, skylights and atriums can be provided in single curved glass or dual curved glass units. A single curved glass dome design will have all rafters and glass units curving up to the apex detail only. Single curved glass domed rooflights, skylights and atriums therefore facet about the opening in plan, producing a similar effect to that of an umbrella. Dual curved glass domes have all framing components rolled and glass units curved in all directions. Dual curved domed glass skylights, rooflights and atriums therefore produce a true domed geometry. Subject to the domed rooflights, skylights of atriums dimensions, hemispherical glass dome domes can be provided.

 

Due to the nature and processing requirements of curved glass, domed glass rooflights, skylights and atriums can be quite costly and therefore conical / faceting flat glass atriums, rooflights and skylights are often considered. Curved dome rooflights however provide an excellent way of producing an aesthetical feature to a room/foyer. In fact due to the natural of refracting light through a curved glass prism, domed glass rooflights will slightly focus the natural light into the opening. Due to the processing nature of curved glass units (especially dual curved glass), there are many additional contracts logistical and programme implications/considerations when constructing domed glass rooflights. In addition typical flat roof applications, domed glass rooflights may also be utilised to complete the entire roof on circular glass roof extensions, conservatories and garden rooms. It is important to note that require supporting apex detailing will increase dimensionally in conjunction with the number of rooflight facets designed.

 

Isometric view of a domed skylight

 

Aluminium Framed Dual Curved Glass Dome with White Resin Interlayer

 

Aluminium Framed Clear Glass Dual Curved Domed Rooflight

 

Structurally Glazed Glass Hemispherical Domed Rooflight

 

Internal View on Structurally Glazed Single Curved Glass Domed Atrium

 

Temporarily Glazed Single Curved Glass Domed Rooflights

 
Bespoke Glass DOMED Rooflights, Skylights and Atriums - Technical Information

 

DESIGN GUIDE – Domed Rooflights, Skylights and Atriums

The following information has been provided as a general guide on the typically requested products and options within the single curved glass and dual curved glass dome rooflight, skylight and atrium range. It is important to note that due to the nature of our bespoke design and build service. You should contact our offices regarding any bespoke requirements outside of those listed and in order to ensure compatibility with the full specification.

 

Most of the dome glass rooflight, skylight and atrium options detailed below may also be selected within our standard online budget quote generator (see tab below), which may be accessed by login into an online trade account.

Min / Max Dimensions & Rooflight Pitch

 

Glass dome rooflight, skylight and atrium applications can be provided up to a hemispherical in geometry (i.e. height = ½ opening width). However, there are many technical restrictions when dealing with curved glass units. Glass domed rooflights need to be provided in a minimum of 8 curved glass units about the rooflights perimeter. Therefore curved glass domed rooflights/atriums are normally only considered for applications over 1.8m diameter (due to the amount of framework and apex size with 8 No. interfacing rafters. Larger glass dome atrium applications will require additional supporting rafters/glazing bays to produce a cill bay width of approx. 1.5m. 

 

Single curved glass dome skylights, rooflights and atriums can be designed to accommodate any glass radius more than 1,000mm. Therefore any single curved glass dome applications less than 2m diameter can not be produce a hemispherical dome height without the glass entering with the eaves or apex detail (or both) at an angle. Dual curved glass dome rooflights, skylights and atriums are slightly less restrictive however each domed rooflight application should be reviewed in conjunction with the complete specification. Dual curved glass dome rooflights/atriums may however provide a true hemispherical geometry. The radial angle about both a single curved glass unit and dual curved glass unit can not exceed 90 degrees (i.e. bespoke curved glass requirements requiring a larger radial angle will need to be provided in two of more glass units).

 

It is worth noting that regardless of the domed rooflight glass pitch range, you will normally experience some form of water retention on the glass (e.g. the small water beads that you will find ‘clinging’ to your steep pitch car windows after a downpour). This is due to the gravitational force on the beads (proportional to their mass) being less than the frictional force retaining the water to the glass rooflight. These beads therefore increase exponentially with a reduction in glass pitch pitch. Although unnoticeable through the steeper pitch areas of a glass dome, these become more apparent (up to approx. 20 – 30mm dia.) at shallower pitches. You will therefore witness a varying effect on curved glass dome rooflights/atriums, where larger retaining beads will be apparent about the rooflights apex and much smaller towards the eaves. Domed curved glass rooflights, skylights and glass atriums may be supplied within a modern day patent glazing system, however this system will not necessarily be suitable for shallower height glass dome rooflight, skylight and atriums applications.

Typical Perimeter Interfaces

 

Weathered Upstands

 

Weathered upstand interfaces are always apparent in domed glass rooflight, skylight and atrium designs. The detail consists of the domed glass rooflight framework flashing over a weather upstand, wall or guttering detail and this detail therefore always applies to the leading edges of rooflights (for rain water drainage). Some glass rooflight applications can utilise an upstand as small as 100mm above the roof finishes below. However 150mm upstands are typical of flat roof applications (to BS standards).

 

Wall Abutment Details

 

Wall abutment interfaces can not be utilised in single and dual curved domed rooflight, skylight and atrium designs. Unless the wall and dome rooflight/atrium is separated by means of a guttering detail, in which case a typical weathered upstand detail will be provided.

Systems Available

 

Structural Glazing (single curved domes only)

 

Structural Glazing (or structurally adhered applications) may be utilised within bespoke single curved glass domed rooflight, skylight and atrium designs. In this instance the structural glazing tapes and adhesives accommodate the rolled rafter framework and glass unit production tolerances. It is important to note that in single curved glass domed rooflights, domed skylights and domed atriums facet between rolled rafter assemblies and therefore produce a varying dihedral angle between the adjacent glass units. A varying stepped edge detail is therefore required on the outer glass pane and the unit’s spacer bar details will therefore splay apart down towards a domed rooflights eaves/cill. In a structurally glazed application the dome rooflight/atriums glass will be black primed on both the internal pane and stepped edge outer to maintain a black reflective finish over the supporting framework. In all instances the domed rooflight glass will be supported by internal rolled rafters and transoms which may be provided in a large range of extrusion sections. More frequently glass dome skylights, atriums and rooflights are supplied with box section rafters. All structurally glazed glass rooflight, skylight and atrium dome designs will produce a complete flush silicone jointed external finish.

 

Framed Glazing (dual curved domes only)

 

Framed Glazing or capped glazing may be utilised within dual curved dome glass rooflight, skylight and atrium designs. Such dual curved domed glass rooflight designs consist of aluminium box section rafter and transom supporting extrusions. The curved dome rooflight glass is then retained using specialist glazing tapes and caps which are restrained from applying direct pressure to the glass. Dual curved domes are then silicone pointed due to potential tolerance discrepancies between the rolled frame and glass, therefore ensuring continuous glass support. It is important to note that dual curved glass domed rooflights, domed skylights and domed atriums are supplied in float laminated glass and due to the production process can not be utilised with many glass coatings (especially soft coatings as the process will discolour the glass). Fully framed/capped dual curved glass rooflight domes, skylight domes and atrium domes are more recently provided in modern box section rafters, however many dated glass rooflight structures may utilise Victorian style T section rafters. Our company possesses the ability to undertake such refurbishment contracts, where system extrusions need to be developed to retain the existing glass dome rooflight/atriums character and aesthetics. Dual curved glass domes can be provided in hemispherical glass dome rooflight, dome skylight and dome atrium designs.

System Materials and Finishes

 

Our company specialises in the utilisation of architectural metals and glass. The required domed glass rooflight, skylight or atrium glazing system/geometry selected may have some bearing on the system finishes available. We are typically requested to provide:-

 

 

Polyester Powder Coated Rooflights, Skylights and Atriums

 

Anodised Aluminium Rooflights, Skylights and Atriums

 

Brushed (Sometimes Polished) Stainless Steel Rooflights, Skylights and Atriums

 

 

Bespoke glass dome rooflight/atrium system finishes may be reviewed in conjunction with the entire design specification.

 

Our company also provides structural steelwork when required as an integrated component to the domed glass rooflight, glass skylights and glass atrium designs we provide.

Glass Specifications

 

Our company is able to supply most of the glass specifications available within today’s market. However, glass specifications on curved glass domed rooflights are restricted due to the bending/rolling process. Soft coat glass specifications can not be utilsed in curved glass dome designs, as will discolour through the heating and bending process. Typically requested glass specifications for rooflight domes, skylight domes and atrium domes include:-

 

 

Single and Dual Curved Glass Designs

 

Double Glazed and Triple Glazed Specifications

 

Standard Low E Specifications

 

Body Tinted Glass

 

Sandblasted Glass

 

Coloured (typically white) Laminates

 

Low Maintenance & ‘Self Cleaning’ Coatings

 

 

The production process of dual curved glass for domes can be a little hit and miss in regards to the number of glass panes the cool successfully after being heated to take form. Each laminated glass pane request 2 No. float glass panes and each double glazed glass unit therefore requires 4 float glass panes. Due to the processing requirements and relatively low success rate when cooling in the oven, dual curved glass is very costly and a larger amount of contingency must be introduced into the programme. 

 

If you have any queries regarding the utilisation of any glass specification within a specific glass dome rooflight application, then please do not hesitate to contact our offices with your enquiry.

Glass Unit Dimensions

 

There are many considerations when reviewing the glass unit dimensions being supplied to a given domed glass rooflight, glass skylight and glass atrium application. Typically curved glass dome skylights, rooflights and atriums are designed with a max width/lateral girth of 1.2m to 1.5m at eaves/upstand level and 2m to 2.5m girth over the supporting rafters. An applications site logistics and the glass handling must also be reviewed and will form part of a domed glass rooflight/atrium’s overall cost. Larger glass unit rooflight applications will require suitable plant equipment (typically a crane) to manoeuvre the glass (delivered in crates) adjacent to the rooflight/atriums opening.

 

Glazing Innovations are capable of providing glass units up to 6,000mm x 3,000mm (although not to this extent in domed glass rooflight, skylight and atrium applications). However our offices should be consulted should your application require large glass units as each application will need to be reviewed carefully.

 

Single curved dome units will have a minimum bending radius of approx. 1,000mm and a maximum rolling angle of 90 degrees.  

Glass & System U-Values

 

Architectural faceting glass conical rooflight, skylight and atrium suppliers will typically provide you with mid pane (or mid unit) U Values. When reviewing a double glazed application with a 16mm (optimum) cavity...

 

Low E coatings tend to provide a mid pane U Value of 1.7 W/m sq K or 1.6 W/m sq K with an argon filled cavity.

 

High performance solar control coatings tend to provide a mid pane U Value of 1.2 W/m sq K or 1.1W/m sq K with an argon filled cavity.

 

Triple glazed applications may achieve a mid pane U Value of 0.6 W/m sq K.

 

Please note that both single and dual curved dome glass can not be produced from soft coat glass (due to discolouration) and both offer different limitations in regards to the hard coat glass specifications that may be utilised.

 

The overall U Value of a glass dome rooflight, skylight and atrium application is very much determined by the system details and glass specification utilised. Well engineered rooflight details that mitigate the extent of the framework retain relatively low U Values. However domed glass rooflights are often less thermally efficient as other rooflight, skylight and atrium geometries.

Design Loadings

 

Dead loads, wind loadings, snow loadings, maintenance loadings and uplift forces are all considerations when designing a curved domed glass rooflight, skylight or atrium. All site specific forces (especially in adverse locations/conditions) should be provided. Domed glass rooflight wind loadings, snow loadings and uplift forces are all site specific and unless provided at sales stage the averages figures below will be utilised.

 

UK wind loadings tend to vary from 0.53 KN/m sq to 3.4 KN/m with a typical average of approx. 1.0 KN/m sq to 1.5 KN/m sq.

 

Snow loadings will also vary depending on your glass dome rooflight application. Applications with surrounding walls and roofs above will have much higher potential loadings and snow loadings are normally not applicable for curved glass rooflight/atrium elements over 60 degrees. UK snow loadings tend to range between 0.6 KN/m sq to 2.0 KN/m sq with a typical average of 0.75 KN/m sq. When combined with maintenance loadings a live load figure of 1.5 KN/m sq is often utilised.

 

Uplift is rarely an issue (due to it acting against the dead load of the rooflight), however should always be considered. Some applications such as domed glass rooflights/atriums above large stair wells may have very high uplift requirements.

 

The glass dome rooflights/atriums upstands must also be designed to take any thrust forces imposed onto the upstands as a result of the domed glass rooflight, skylight or atriums design. Sometimes tension bars may be utilsed across the domed rooflights opening to mitigate such forces.

Typically Requested Inclusions

 

Typically requested glass rooflight, skylight and atrium inclusions are:-

 

 

Secondary or Internal Glazing

 

Down Lighters

 

Chandelier Supporting Apex Details

 

Rooflight Eaves Guttering

 

Trickle or Forced Ventilation (Typically through the upstand detailing)

 

Stepped Edge Glass Units

 

Low Maintenance Glass Coatings

Contract Programming

 

It is imperative that contract programmes are confirmed via formal quotation issue and/or at the time of order placement. Domed glass pyramid rooflight, skylight and atrium programmes vary depending upon size and production requirements. However are typically on an o/all programme (prior to site installation) of 12 to 16 weeks for single curved glass domes. Due to the processing nature of dual curved glass units, true dual curved glass dome programmes incorporate additional contingency and are often quoted on 14 to 20 week programmes. These programmes includes for the preparation of bespoke general arrangement drawings, however does not include for the associated approval period of such.

 

Due to the nature and cost of glass as a material (especially curved glass), it is important that every effort is made to ensure that an architectural curved glass domed rooflight, skylight and atrium design is right. Now would therefore be an excellent time to contact our sales team, who are looking forward to casting some light over your requirements.

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