12 October 2015

Why to use a dry fix ridge system

Dry fix ridge systems are typically quicker and easier to install than mortar fixed ridge tiles, provide better ventilation and will perform more reliably. However, as they can vary, it’s important to give any potential dry system detailed consideration to ensure it meets the specification needs.

Focusing on the ridge area, dry fix systems replace mortar joints with plastic inserts, known as unions, creating the visual appearance of a mortar joint but with a hidden weatherproofing system that carries away the water. In addition, they incorporate a ventilated strip (or ridge roll) that ensures moisture laden air is vented from under the tiles.

Many contractors are fast realising the benefits of such systems – one of which includes quick fix options, whereby all the components come ready to use in a box.

There are many different versions available on the market to deliver ultimate onsite efficiency - ours is called Universal Ridgefast and is compatible with all Marley Eternit tiles, as well as other brands. 

Most quick fix systems include all the relevant components needed for a simple, secure installation including:

- A ridge roll
- Ridge batten brackets
- Ridge unions
- Ridge union clamps
- Compatible screws and nails

Specialist adhesive tape and a roll on applicator are also recommended to secure the ridge roll and are offered through Marley Eternit’s Universal Ridgefast.

Six steps for dry fix ridge system installation

1 - Felt and batten the roof in the normal way before securing a ridge batten bracket to each rafter
2 - Install the ridge and top course batten
3 - Finish tiling/slating up to the ridge
4 - Position the ridge roll centrally across the length of the ridge batten and secure using felt nails
5 - Remove the adhesive cover strips that run along the metal corrugations on the roll and firmly press the corrugations onto the tiles/slates
6 - Fix the ridge tiles using union clamps in the centre of each ridge union and secure each clamp with a screw


Why stricter fixing standards are required

With the ‘grace’ period of the previous BS 5534: 2013 standard now over (as of 1st July 2015), all roofing work should now be completed under the revised BS 5534: 2014 standard.

To recap, the revised BS 5534 requires more stringent fixing requirements for pitched roofs to make them more secure against extreme weather, bringing the UK in line with the equivalent Eurocodes.

When looking more closely at the impact this has on fixing options, perhaps the biggest change applies to mortar bedding. This traditional technique is no longer deemed sufficient on its own, meaning when applied to areas such as the ridge, a mechanical fixing is also required.

In almost all projects, dry fix is overwhelmingly the best option to meet the BS 5534 changes. Indeed, often by the time a mechanical fix is added to a mortar bedding it will have been more efficient to use a dry system in the first place. In addition, dry fix also gives the added benefits of ventilation, improved security and a reduction in ongoing maintenance costs.

Heritage sites may require a more traditional mortar bedding finish and in these cases there are solutions available to meet both the aesthetic and BS 5534 standard.

Mortar fix vs dry fix ridge systems

There are a few occasions when dry fix systems may not be suitable.

When a project requires the traditional look of mortar bedding - as can be the case with heritage sites which need to adhere to stringent planning requirements - there are ridge fixing kits available to provide a compliant means of mechanically fixing through mortar. 

When considering this approach, using a proven solution that is BS 5534:2014 compliant, such as the Marley Eternit Mortar Bedded Security Ridge Pack, is paramount. 

While systems such as ours have been designed to offer easy installation it’s important to remember that it may be more time and cost effective to use a dry fix system in the first place. Therefore, it’s important consideration over whether mortar bedding is the right option is needed at the earliest specification stage. 

We’d love to hear your views on dry fix systems – leave your comments below.


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