Frequently asked questions

  • How do I get a quote for Rationel windows and doors?

    Rationel Windows work with a network of Distributors and we would refer your details to one of them, depending on your area and the requirements of your project. We would just need window range, specification, dimensions and drawings (elevations and/or window schedule).

    Click here to get quote

  • What is the lead time for windows and doors

    The lead time depends on the requirements of your project. As a standard we are working on a lead time of around 8-10 weeks from sign off.

  • What is the lead time for a quotation?

    After we refer your details to a Rationel Distributor, they will contact you within 48 hours. You should have a quotation back in no more than 5 working days.

  • Are Rationel windows SBD certified?

    Rationel windows and doors have been tested and marked according to several national and European standards, including "Secured by Design".
    Read more about SDB here

  • What product ranges do you offer?

    Rationel offers windows and doors for all building styles and shapes. Read more about our different product series here

  • Do you have a showroom?

    We have a showroom in our Bicester office. If you wish to see our windows, please do not hesitate to ring the office and book an appointment.

    The office is open Monday to Thursday 9am-5pm, Friday 9am-4pm. We also have some Rationel Distributors around the UK with showrooms. Please call our reception for more details.

    Find contact information here.


  • What colours do you offer?

  • What are the maximum and minimum requirements?

    You can read more about the individual maximum and minimum sizes in the section "opening functions".
    Click here to learn more

  • Does Rationel do Curtain Walling?

    No, unfortunately Rationel Windows are not CWCT certified, which is an Air permeability, watertightness, wind resistance and impact mandatory test for all curtain walling.

  • What is the air flow of Rationel trickle vents?

    The equivalent area of the trickle vent is 2163 mm² in DOMUS/ALDUS and 2224 mm² in Rationel AURA and AURAPLUS when placed in the jamb.

  • What does the information in the panes spacer mean?

    The information printed on the spacer bar between the panes of glass has information about pane size, energy values, order and position number.

    Example of text in panes spacer:

    22-04-2011 83314 2659 / 24 EN 1279 2601013 Optifloat Clear 4mm/TGI RAL7035(18)/Argon/Optitherm S3 4mm 764x530 1254518 / 7 ENERG:A U=1,14 g=0,59 Lt=0,80

    22-04-2011 Production date
    EN 1279 Production standard
    2601013 Panes item no. at Rationel
    Optifloat Clear 4mm/TGI RAL7035 (18)Argon/Optitherm S3 4mm Panes structure
    764x530 Size in mm.
    1254518 The window/door order no. at Rationel
    7 Windows/doors position no. at Rationel
    ENERGI:A Energy Class
    U=1,14, g=0,59, Lt=0,80  Energy values (Ug, Gg, LTg)

    The amount of information depends on the age of the window. In newer windows you can find the above mentioned information.

  • Can I get a sample of your products?

    If you would like to receive a window chop sample, please email

    Alternatively, dial 01869 388825 to contact our stores department.

  • How do I maintain the paint finish on my windows and doors?

    Good maintenance of your windows can help to retain their shape and strength for many years. When the timber surface is to be cleaned, it is a good idea also to have a look for any small cracks and crevices in the paint surface. Especially the windows on the south and west-facing facades as these are the most exposed to the sun and weather. If the protective surface has cracks or fissures through to the wood, Rationel Windows recommends that you repair the damage immediately.

    Generally, when the weather begins to discolour the paint on your windows and doors, it is time for maintenance.

    We recommend that you consult the Rationel Operations and Maintenance manual. click here to download. If your windows are painted with a translucent colour, you will find instructions here.

    If you have bought ALDUS, AURAPLUS or FORMAPLUS (timber/aluminium) maintenance is very limited. You can make do with washing them outside a few times a year, but it is best if it becomes a habit to wash them when washing your windows.

  • How to treat yellow extract from knots?

    The yellow spots can be corrected as follows:

    Take a good cloth soaked with ethanol and wipe lightly on
    the extraction. Rinse with clean water.

    Resin that is crystallized can be removed with a stiff brush or scraped away. If the painted surface has been damaged in the process, sand the area with fine sandpaper and repaint with a soft brush or a smooth surface roller.

  • Condensation on the window pane

    Dew on the outer side of the glass is positive as this is proof that the window is very energy efficient, and that it functions properly.

    In certain weather types, for example a clear frosty night, when there is more heat radiation from the earth towards the sky there may be periods in the early morning hours where the outer surface of a low-energy pane is colder than the air outside. This results in condensation on the glass surface. The dew disappears when the air temperature rises during the day.

    If there is condensation on the inner side of the glass, you will need to ventilate the room. It is a sign of too high relative humidity inside and should be reduced to prevent rot, moisture damage and a poor indoor climate.

    Dew between the two pieces of glass is a sign that the sealed glass unit is punctured and should be replaced.

    >> Click here to read more about creating a healthy indoor climate

  • How do I remove glue residue from the glass?

    Glass labels on new windows can be removed by soaking them in water. Label residues on the glass can be removed by gently using a cleaner designed for ceramic hobs.

    >> Click here to download Operations and Maintenance Manual

  • How do I detach sash and frame?

    When installing it will in most cases be useful to separate frame and sash.

    >>  In the Operations and Maintenance Manual you can read about separation of the frame and sash. Download here.

  • What is the product warranty on Rationel windows and doors?

    Subject to our conditions, Rationel guarantees that the goods supplied will comply in all material respects with their specifications and be free from defects in materials and
    workmanship for a period of five years from the time that the risk in them passes from Rationel to the customer.

    Furthermore, Rationel's products are covered by a product liability insurance covering damages caused by a Rationel product. The insurance applies if the damage is proved to be caused by a fault caused by Rationel. The insurance does not cover consequential loss, loss of profits or any other indirect loss.

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