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Conservatory, Orangery, Window and Door Specifications

We are a FENSA registered company and issue a CE Declaration of Performance with all replacement windows and doors. Click here to view Atrium's BFRC & CE Certification

On this page you will find specification for our orangeries, conservatories, windows and doors.

Windows and Doors

Windows may be manufactured in a variety of styles e.g. in stormproof casement, flush casement (Listed or Conservation), flush casement Mk2, narrowline flush casement, vertical sliding sash, mock sash (3 types), vertical slide and tilt and finally french opening.

The particular specification of each varies to achieve a desired end result. However they do have many things in common. For the purpose of this general description these are set out below.


We only use hardwood. Each timber has a particular character which must be born in mind. For a highly finished coloured or lacquered item we would commonly use Sapele or for a more rustic stained or clear timber appearance we'd use Idigbo, a commonly used and stable oak substitute.


The detailed moulding applied to all timber edges will radically alter the overall appearance so we offer a vast range of mouldings from e.g. "Stopped Church Chamfer" for a rustic appearance through simple "Arrass" for the modern or minimalist customer to "Lambs Tongue" to achieve a fancy Victorian appearance; and many more besides. A truly bespoke outlook on design!

Factory applied pre-finish

For the Sapele item we would conventionally select a lacquered timber colour by first supplying a sample and only when we have achieved just the right tint and this has been agreed with the customer would we proceed to spray finishing. If a colour is required we would normally ask you to select from the Farrow and Ball Heritage Range or to supply a colour sample for us to match. When the finish has been agreed the windows would be sprayed with a system requiring three consecutive coats. The result is a very smooth satin finish requiring a minimum amount of maintenance in the future. Even then the cill nose and lower glazing beads are normally the only parts requiring particular attention. All other maintenance is normally for the purpose of cosmetic appearance only. Internally no repainting is ever required. The maintenance period varies between five and eleven years depending on the colour and location (lighter colours need least maintenance) and does not involve "stripping back" or the time absorbing preparation required for more normal finishes.

Every effort is made to minimise the need for later maintenance. We do however have a Service Manager who may be contacted through our main office and who will deal with anything you would prefer not to.

Where Idigbo has been used for an "oaky" rustic appearance most customers choose to have the inside either unfinished resulting in a very pleasing bleached honey colour or with a sealing coat of O.S. Waxoil. Outside the usual choice is a "pre-aged" oak stain. This results in a semi-matt "aged oak" appearance. The windows are normally left to take on an "aged" appearance thereafter.

Handles, Hinges and Furniture

We commonly offer a choice of 15 designs and finishes from a modern chrome range through to "monkey tail" black iron items for the more rustic appearance. All handles are normally lockable as are the stainless steel friction hinges we use. Security is an important factor and designs are normally altered to achieve a desired "high security" result.


Sealed units may be specified to achieve a whole range of very desirable results. Inevitably the more "high tech" the sealed unit the more expensive so a full discussion of "benefit" against "cost" is the only way to achieve the right balance for you. Generally all units are 24mm thick (a 16mm cavity). Toughened glass is always used for conservatories and elsewhere where Document N of the Building Regulations require. Windows and doors must achieve a particular insulation rating (U. value) and any glass proposed or specified will achieve the desired result (Document L1 Building Regulations). We must subsequently register your windows and doors with FENSA (An organisation set up to "police" our industry and to protect you from problems caused by shortcuts). A small selection of performance characteristics available include: toughened glass for safety and resistance to breakage, low emissivity (Pilkington K) argon gas filling and warmedge spacer for enhanced insulation. Pilkington Activ glass for the convenience of self cleaning and also for resistance to glare and U.V. filter and glare reduction.

For the purpose of both security and resistance to the weather all sealed units are fitted into an adhesive silicon bed. Later removal of the glass then becomes particularly awkward and impossible to do silently.


We are particularly proud of the doors we manufacture. Made with the same unique Atrium jointing system as the windows (sealing off end grain and thus maintaining stability over the years) all doors are 2 1/2" thick so we can glaze them with full 24mm sealed units. They may be made in a bewildering range of styles and types (e.g. Residential, Stable Doors, French Doors, Bifold or Multifold Doors and Patio Doors up to 19 1/2 feet wide for the truly spectacular view). All doors nevertheless have a few things in common. Each hinge we use contains its own gearbox to allow us to adjust the position of the door in any of three directions. The low threshold always complies with Document M (wheelchair access) Building Regulations. The locking system (Cremone) results in very high security. The lock is in effect a full height set of three interlinked mortise locks with a separate 7 pin key barrel. The door is frequently the item which falls short of expectations and results in disappointment. We are confident that we produce one of the very best doors and door systems available.

There are many aspects of window and door manufacture and specification which would only be tedious at this stage. Such details are nevertheless critically important and very particular to your windows and doors. Please discuss these details with us in full. Neither you nor we want an outcome which is less than truly impressive.

Roofs to Conservatories and Orangeries

Many elements of timber specification, moulding and finish have been dealt with in the previous sections on Windows and Doors. Roof structures do nevertheless have very particular requirements in the area of structure, glazing and maintenance.

As before the range of types and designs is very extensive so this specification can "at best" be a generalisation.

Every roof must be carefully designed to ensure sound structural integrity. In respect of conservatories this determines the size and angles of all roof parts, the method of mechanical jointing at eaves rail level and whether a tie bar is necessary (though you may want one for reasons of appearance alone). In extreme circumstances to achieve even greater strength and rigidity we will laminate certain timber sections or indeed laminate with a core of steel plate. The widest "free span" structure we have produced (over our 35 year history) is 11.4 metres (37 1/2 feet). Every effort will always be made to maintain symmetry of design but it must be appreciated that structural considerations must come first.

Future maintenance can become a big issue so to make a roof as "maintenance free" as possible we advise the use of aluminium outer glazing caps and Pilkington "Activ" self cleaning glass (which in addition offers many other benefits besides).

We would normally match the style and colour of the house guttering but you may prefer a cast aluminium alternative in which case this would be coloured to match the conservatory.

Orangeries are becoming far more popular. They may be designed to take advantage of the more liberal planning attitudes applied to conservatories ("Partially Exempted Buildings") yet also to become more of a stylish extension to your home. In essence their design is similar in many ways to conservatories. The roof however is constructed as a raised glazed atrium built onto a stylised flat (2° pitch) roof. Structural considerations are the same as a conservatory but in addition the flat roof must be permanently sealed to resist any leaks. Historically this would have been done with lead or mineral felt tar and chippings. Both methods were very unreliable and imposed severe limitations on design. Fibreglassing became a popular alternative but its application is temperature critical - not easy in our climate. We overcome this problem by sheathing the whole roof with weldable EPDM rubber to form a non slip one piece flexible barrier to the elements. Whilst a relatively new system in roofing this has been proved to have a life span in excess of 120 years (BBA accelerated testing carried out to 120 years) - We would suggest: a pretty reasonable lifespan!

A cast aluminium guttering (coloured as the rest of the building) is fitted to take drainage from all round the roof area as you would expect from a building with a conventional pitched roof. The Ogee style guttering and mouldings fitted to the extra deep fascia create the appearance that along with the illuminated perimeter ceiling becomes an "Orangery" and creates the desired stylish extension to your home.

Due to the flexible bespoke nature of our products misunderstandings may become a problem. We encourage you to fully discuss every element of your building and to be very particular - we certainly will be.

Click here to view Atrium's BFRC & CE Certification


For enquires, please call us on 01544 231769 (standard call rate),
or 0500 498448 (free from most landlines) or use the contact form on this website.