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  • Water Build-Up On Rooflights Explained

    What is Ponding?

    Water Build Up or Ponding on a rooflight refers to the accumulation of water on the surface of a rooflight, which is a type of skylight or window installed on a roof to allow natural light into the building below.

    When water gathers or forms puddles on the rooflight’s surface, it can create several issues:

    • Leaks: If the rooflight is not properly sealed or if its drainage system is inadequate, ponding water can seep through gaps and cause leaks in the building below.
    • Material degradation: Continuous exposure to water can degrade the roofing materials and the rooflight’s frame, reducing its lifespan and effectiveness.
    • Reduced light transmission: Ponding water can obstruct sunlight from entering the building.

    In most cases, the risk of ponding can be reduced considerably or even removed completely by ensuring that the rooflight is installed on an upstand at the correct pitch.


    Rooflight Pitch

    With the exception of walk on specification glass rooflights, all of the fixed flat glass rooflights sold at rooflights.com are designed to be installed on a builders upstand at a minimum 3 degree pitch. The design of the rooflight means no capping needs to be fixed to the perimeter of the glass, so rainwater is free to run off the rooflight. Provided the minimum pitch is achieved, run off can be made even more effective by installing at a 5 degree pitch.

    If you are unsure how to go about achieving the correct pitch, you can check out our handy Flushglaze installation video here.


    Cost-effective Glass Treatment

    Another great way of maintaining the finish of your glass is by specifying a rooflight with Enduroshield Easy Clean coating; this cost effective glass treatment acts like a non-stick surface on the glass by filling in imperfections at a microscopic level. Water is then able to run off much more freely, thus reducing any likelihood of water ponding on the glass.

    Enduroshield Easy Clean also makes regular cleaning intervals far more effective and easier to carry out. It’s similar in principal to waxing a car; after treatment rainwater beads off the paintwork and in subsequent washes, the water seems to glide over the surface. For more insight into rooflight cleaning, see our blog post.



    For more information give us a call on 01379 771002 or browse our online rooflights shop.