Laserlite Multiwall Installation Official Guide with Tips and Hints
See the official Laserlite Multiwall Installation Guide here, or read on for a few other tips and tricks for planning and installing Laserlite Twinwall Polycarbonate Sheeting.
Structure – what is needed to support the sheets.
Laserlite Multiwall will require some structure to support the sheeting and aluminium joiners.
There are two standard options for structure design:
- Rafter only (see image below) – here you cannot see the H Bars from below as they are sitting on top of the rafters. If you are using rafters only, the rafters should have 1070 mm from the centre of one to the next. If you have rafters that are closer together you can still use this design – but you will need to trim the sheets down to suite the spacing.
- Rafter and Purlin design (see second image below) – here you can see the red smaller purlins running across the rafters – the rafters hides every other H bar, so you can see some H bars in between. The H bars will be screwed to the purlins. If you are using purlins they should be no more than 1200 mm apart.
Option 1 is the most popular design as long as you are not in a high wind area. If you are in a high wind area – you should do this (and chat to us about what can be done).
Structure design tips for a great result:
The main design feature that is often overlooked is PITCH – a good fall on your roof will help in a number of ways. Firstly, it helps to keep the roof looking clean. Because you can see through it, it is particularly worth thinking about. Secondly, it stops any moisture from sitting in the sheet. This can lead to the sheets becoming dirty inside – making them look bad. Thirdly and finally it helps with waterproofing!
The minimum recommended pitch is 5 degrees – this equates to 88 mm of fall (drop) for every metre in length of the sheet. For example, a 4.0 m sheet will need to be 352 mm lower at the gutter end to achieve adequate fall to keep the sheets looking good!
One of the most common questions we get is about light and heat transfer. This will come down to the colour that you choose. Click the table HERE to see a comparison of the colours available. The rule of thumb is that the more light you have – the more heat you have. Sometimes it will be a conflicting priority.
The sheets are 10 mm thick and 1050 mm wide, when installed with the H Bars (one or two piece) they will have 1070 mm centres. Sheets are available from 1.5 m to 9.0 m long.
Sheets are joined using an Aluminium H Bar – these can be one or two piece. Under normal conditions all of the screws that hold the system down will go through the H bar.
Gasket – a rubber gasket is used between the sheeting and the H Bar – this is for waterproofing and allowing the sheet to move within the aluminium framework during expansion and contraction.
Aluminium Edge Bars are very similar to H Bars – but they have one side of the H closed off. They are used on the sides of the structure to make the unused edge look tidy.
Sealing tape – applied to the bottom (gutter) end of the sheet to cover the open ‘flutes’.
Breathing tape – is applied to the top end of the sheet to cover the open ‘flutes’.
Aluminium End Cap – Aluminium sections that are used to cap off the open ends of the sheets top and bottom.
Find the Laserlite Multiwall Installation guide here.
Answers to the most common questions:
- The sheets are UV2 – they have UV protection on BOTH sides, this means it does not matter which way up the sheet goes.
- There are 2 DIFFERENT gaskets. One for the end cap and one for H Bars. It will make it very hard to put the system together if you have them mixed up.
- Sheets should run with the open flutes running WITH the fall.
- If you have trouble getting the the sheets and gasket into the aluminium bars (firstly refer to point 2), you can spray a little soapy water onto the gasket to reduce friction during installation.
Finishing the Job
Once the roofing has been installed you may choose to add flashing to assist with water proofing. See below images for the main types of flashing that you may need to consider. All of these are provided by others (we don’t sell them).