Most Bifolds sold today seem to end up in new ground floor home extensions, usually Installed before any internal plastering has been started.

When internal reveals aren’t plastered Installers have a choice to use a traditional through-fix method or the strap-fix method for securing the outer frame.

Regardless of which method you employ, it’s essential that you have a solid, well packed outer frame to securely hold the weight of multiple glazed panels.

Through Fixing Method

My guess is that the majority of Installers still use the more traditional through-fix method, using either “masonry screw”, “plug” or “Fischer bolt”, as it’s a tried and trusted way to get a secure outer frame.



Depending on the substrate the outer frame is being fixed to up to 6 fixings may be required on a typical outer frame jamb.

As fixing centres are largely predefined according to the Installation instructions, drilling holes through the outer frame and into masonry can be a tricky task.

Modern hammer drills have been known to dislodge or break apart bricks or blocks meaning the plug becomes loose and fails to hold the screw in place. (Ive heard this described in many ways like “Crumbling Brick”, “Blown Brick”, “Spinning Plug and many other colourful terms)

I’m sure this has happened to every Installer at one time or another, where when attempting to tighten the screw it spins the plug and the fixing becomes useless as it cannot apply pressure to hold the outer frame in place!

So when this happens what are your choices?

  • Use a repair plug & screw?
  • Slightly skew the drill at an angle to find a more solid hole in the masonry?
  • Abandon the hole altogether and cap it with a colour matched plastic cap?


Not a very appealing choice!


Strap Fixing Method

Most fixing straps are system specific meaning that, with a simple twisting motion, they can be securely fixed in place at any position around the outer frame sections.

The immediate benefits of being able to quickly secure fixing straps in position are;

  • As Bifolds are usually fairly wide, they can be difficult to handle whilst you’re trying to make them perfectly plumb, square and level, even for a 2 man team. But, by using fixing straps all around the outer frame, Installers can quickly put a temp fixing through the top straps at each side, thus securing the outer whilst you perform correct packing, before the final fixing.
  • Using this method means that you won’t need to drill visible holes in the outer frame, which always provides a much more favourable finish in the eyes of the customer.
  • Generally, these straps are fixed to the outer frame at a 90 degree angle, but it is also possible to have them set at different angles, for example when you need the fixing to go into a mortar joint to provide a more solid fix.
  • There are usually multiple holes along the length of the fixing strap in which to secure the fixing screw, offering an alternative when you find yourself in the inevitable “crumbling brick” scenario
  • As Bifold Doors are usually wide, the steel beam or RSJ that takes most of the load on the head of the doors is a much heavier gauge than a normal light steel Catnic  This means that drilling into it can be difficult. In addition to this, the fact that there is masonry or brick sat directly on top of the steel means that, as soon as your HSS drill bit designed for use with steel comes into contact with the masonry, it will immediately be blunted. Using straps allows you to drill the steel with no chance of coming into contact with masonry.

Summary Benefits of installing your next Bifold Doors using fixing straps:

  • No drilling holes in the outer frame for customer to see
  • Allows alternative fixing point when you get a “crumbling brick”
  • Easy to temporarily fix whilst you make adjustments to get perfectly level, plumb and square
  • No more fixing through thick gauge steel directly into the masonry


How do you prefer to fix your Bifolds? We’d love to hear your thoughts and comments below!