Glazing Bars are used when you want to glaze a roof with Polycarbonate Sheets or Glass. You can have Rafter Glazing Bars or Self Supporting Glazing Bars and which one you choose will be determined by what type of roof you are looking to build.

Rafter Glazing Bars

The term Rafter Bar means that the glazing Bar will be fixed down onto an existing timber or steel rafter. These are the beams that come from the wall to the front of your roof or eaves beam. Rafter bars are fixed down onto the rafter and the polycarbonate or glass is held in place with either a PVC or Aluminium Cap. If you are creating, replacing or refurbishing a timber framed roof then you should use Rafter Bars.

PVC Capped Rafter Bars    

PVC Capped Rafter Bars are a lightweight, effective and easy to install method of glazing a roof. They are suitable for polycarbonate roofs but not for glass.

This type of Rafter Glazing Bar has a PVC Cap that is available in White, Brown or Anthracite Grey. This cap snaps down into an aluminium base which is fixed directly onto the existing rafter. Because of how the top cap is fitted, it is often referred to as a 'snap down bar' or a 'snap tight bar.' The bar comes complete with rubber gaskets and an end cap. The Gasket is fitted into existing grooves on each side of the aluminium base so that when the polycarbonate or glass is fitted it provides a snug waterproof fit.

There is a PVC Capped rafter bar that will glaze 10mm, 16mm and 25mm Polycarbonate Sheets and another Glazing Bar that accommodates 25mm and 35mm sheets, both of which are available in a range of different lengths.

PVC Capped Glazing Bars are simple to install. Begin by fitting the gasket into the grooves on the outside edges of the aluminum base. Screw the aluminium base into the roof rafter at approximately 300mm centres. Once the Aluminium base is fixed in place, locate a sheet of polycarbonate onto the gasket ensuring there is around 2.5mm gap between each edge of the polycarbonate sheet and the aluminium base’s central upstand. This allows for the sheet to expand and contract as the weather changes. Once your polycarbonate sheets are in place simply push the cap down to the required sheet thickness. You will hear a click or snap as the cap locks into place, hence this bar being known as a ‘snap down bar.’ The end of the bar can then be finished off by pushing the end cap into the grooves on the Aluminum base.

Aluminium Capped Rafter Glazing Bars  

Aluminium Capped Rafter Bars consist of a rubber base gasket, a 2 piece Aluminium Cap, some thread in top gasket and a metal end cap. This Aluminium capped glazing bar is powder coated for a professional, hard wearing finish that will look great for years and requires no maintenance. The Glazing Shop supplies two widths of Aluminium Capped Rafter Bar, 50mm and 60mm. The width of the bar corresponds to the width of your wooden rafters. The 50mm corresponding with the two inch surface of the popular timber size. Aluminium Capped Rafter Bars are suitable for glazing your roof with glass sheets as well as polycarbonate.

Begin installation by laying the rubber base gasket onto the top of the rafters. The gasket can be fixed down using panel pins fixed at around 300mm centres. The end cap should then be screwed into place. The end cap is important as it not only finishes the roof off but it prevents the polycarbonate or glass sheet sliding down the roof.

The Aluminium top cap has two pieces. The larger part is screwed down through the the middle into the rafter to the height of the polycarbonate or glass sheet. It is important not to overtighten the screws otherwise the polycarbonate will be crushed or the glass damaged. This bar is often referred to as a 'screw down bar.' Before fixing the larger top cap down make sure the gaskets are slid into the grooves along the edges of the bar. These will provide a watertight seal on the polycarbonate or glass.

One advantage of the Aluminium capped Rafter Bar is that a single bar can accommodate all thicknesses of multiwall polycarbonate or glass simply by varying the depth to which the fixing is screwed down.  When the top bar is fixed down gently push down the smaller top cap into place to hide your screws.

This is the perfect low profile rafter bar for polycarbonate or rafter bar for glass roofs. Aluminium Rafter Bars are available in White, Brown and Anthracite Grey and a range of sizes. We  also supply these bars in a mill finish should you want to powder coat them to another colour. If you need any help in selecting the right rafter bars for your job please call 01536 446395 and we will be happy to help you.

Find out what trims and accessories you need to complete your roof.