How to Cut Corrugated Bitumen Roofing Sheets

Corrugated bitumen roofing sheets are easy to cut to size at home or on site. This is why they are loved by homeowners and the trade for installation on a wide range of roofing projects, including shed roofs, garages and stables. Available in a range of four colours, bitumen sheeting is a simple way to add some colour to your garden whilst being cost effective. 

Most installations of bitumen roofs only require the sheets to be overlapped widths and lengthways to cover the roof so often there is no cutting required! However, when corrugated roofing sheets do need cut to size, when a roof is a more bespoke length, it is easy to do!

One of the many benefits of corrugated bitumen is that it can be easily cut across its width or down its length when required. Cutting bitumen corrugated sheets by width or length follows a similar method.

When trimming sheets to size for your roof project, always remember to allow for the recommended overlaps both in length and width. The distance you will need to overlap your sheets depends. Please see our bitumen roof sheet installation instructions for specific details to suit your roof set up.

If you are unsure of your roof pitch then use our handy roof pitch calculator. The roof pitch calculator can help calculate roof pitch in degrees or percentage as suited. The reason understanding the pitch of a roof is important is because it affects how much support you will need and the speed of rain run off. Generally speaking, the shallower the pitch the more support required due to slower water drainage.

To learn how to cut bitumen corrugated sheets to size simply view our How2 Video above or follow the steps below.

Tools Required:

  • Hand Saw (an older fine-toothed saw is easiest)
  • Spray Lubricant
  • Pencil or Pen
  • Straight Edge level or timber
  • Tape Measure
  • Appropriate PPE equipment

How to cut bitumen roofing sheets

1. Lubricate your saw generously on both sides. This reduces friction making cutting easier.

2. Using the tape measure, measure the length required for your roof. N.B Remember to consider the required overlaps, over the eaves (up to 70mm) or sheet to sheet.

3. Mark a cutting line to follow on your sheets using a pencil and a straight edge. 

4. Starting slowly, begin to cut the sheet with your saw. Top Tip: Tilt your saw vertically to ensure an easier and smoother cut

5. Increase your speed as you move further into the sheet. Apply more lubricant as required to maintain low friction.

6. Repeat this method when trimming the width. 

7. When cutting down the length, to reduce the width, remember to allow space for the Rock n Lock Flashing on the outside wall or gable. The Rock N Lock Flashing gives a roof a longer lifespan, less risk of wind uplift and a smart gable finish!

Common questions about cutting Bitumen Sheeting

How to cut bitumen roof sheets neatly?

Sometimes using an older hand saw can make cutting Bitumen roofing Sheets neater and easier as the more worn teeth apply a softer force, meaning a smoother cut!

When cutting lengthways, cutting down the centre of the trough is the easiest place to cut from a neat edge.

Can you get bitumen roof sheets 3m long?

No, due to the manufacturing process, bitumen sheets are only manufactured in 1m or 2m lengths. If you are looking for a longer solid colour sheet option then Corramet corrugated sheets are worth considering as they are available up to 3 and 4 metres long.

What tools to use to cut bitumen roofing sheets?

Using a hand saw is the easiest way to cut bitumen roof sheets and is what we recommend as most DIYers have a hand saw they can use. If you have a circular saw that that is also another good saw to use to cut bitumen roofing sheets. You can also cut bitumen sheeting using a sharp retractable knife!

How to cut bitumen roof sheets using a knife?

To cut bitumen roofing sheets using a knife simply mark a cut line and the score down the line several times until nearly through the sheet. Then fold back the sheet along the cut line to separate the two section, running the knife down between if still attached.

Two important points to note when cutting bitumen sheets with a knife:

  1. It is only easily done done lengthways, down a trough, so you are best to use a saw if you are cutting across the width.
  2. The knife has to be sharp to get a clean cut so be very careful when using it and always cut away to the side of your body.

Are premium and DIY grade corrugated sheets cut the same way?

Yes - both premium bitumen sheets, like Awnapol premium sheets, and DIY grade bitumen sheets are cut using this same simple method. In many ways, cutting premium corrugated bitumen roofing is easier due to its extra rigidity and sturdiness.

How much gap to leave for the Corrapol Rock n Lock flashing at the edge of a roof?

Using a Rock N Lock Flashing on the edge of a corrugated roof is essential for a long lifespan and reduced wind uplift risk. When installing corrugated roofing you should allow a maximum of 42mm at the edge for a Rock N Lock Flashing. With a sheet 42mm away from the edge of your roof (gable or wall) the Rock N Lock Flashing will be flush with the outside edge.

This is the same distance to leave whether you are using a Rock N Lock Wall Flashing against a side or abutting wall or a Rock N Lock Gable Flashing at an open edge or verge.

Other bitumen roof sheet How to videos that you many require...

Here some of our other popular how videos that you may find helpful for your roofing project:

How to overlap corrugated roofing sheets

How to fix corrugated roofing sheets

If there are any other question you would like us to create a 'How to' video about please get in touch via our contact form.

Have a question about installing Corrugated Bitumen Roofing Sheets?

Chat to our product experts on our Live Chat with any unanswered questions you have. Alternatively, feel free to leave a comment question below and we'll respond publicly to help any other DIYers with the same question!

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