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Frequently asked questions


  • 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 or PATUS + (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

    You will primarily experience knot extraction on the windows and doors delivered before June 2009 since Rationel Windows from that date onwards have used only finger-jointed timber on painted products. That means timber where the knots have been removed before windows and doors are made out of it.

    If the wood is not jointed, you will typically find resin extraction or yellow extract from knots. Wood is a living material that works, therefore extraction may occur. 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 to remove glue residue from the glass

    If the sticker on the glass stays on too long, there may be glue residue on the window. Stickers are easily removed with toothpaste, lamp oil, cleansing cream for ceramic hobs and possibly a glass scraper.

  • How do I adjust my windows and doors?

    It is possible to adjust virtually all types of windows and doors from Rationel.

    >> Click here to download Operations and Maintenance Manual


  • The sealing between window and wall

    For the sealing of Rationel products , we recommen d usin g the sealing branch recognized principles.

    Read more about sealing here.

  • 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.

  • How to join units in multiples?

    For advice and guidance on joining in multiples here.

  • How do I change glass in my window?

    If it is necessary to change the glass, it is possible to do it yourself on DOMUS and ALDUS windows and doors. Please follow the instructions in the guides below.

    How to dismount glass in windows and doors

    How to change glass in fixed frames

    How to change glass in opening windows

    How to change glass in windows with timber glazing beads

    In cases with PATUS og PATUS+ is would be better to buy a new sash and replace the old.


Were you unable to find an answer to your questions?

You are always welcome to contact Rationel Windows for advice and guidance.

  • Rationel Windows Ltd.
  • 7 Avonbury Business Park
  • Bicester, OX26 2UA
  • United Kingdom
  • Phone +44 1869 248 181
  • Legal disclaimer