How to fit bitumen roofing sheets?

Whether you are roofing a shed, a summer house, a small agricultural building or a Garage, Bitumen Roof sheets are a perfect cost effective corrugated roofing solution. Easy to install and very DIY friendly, no specialist tools or skills are required, and they are available in a selection of colours to suit your project. Easy to handle, lightweight and simple to cut with a handsaw these are great for professional and DIY customers alike, available in set 2m length sheets they can be cut down to suit smaller roofs or easily lapped end to end for larger projects. We have provided these sheets for projects as varied as Children's Play houses to Horse Stables, and from Garden Offices to Pet enclosures.

As a shed roof covering Coroline Bitumen Roof Sheets can be installed directly on top of existing shed felt so are perfect if you wanted to spruce up a tired looking shed roof, or you have a new shed provided with a felt roof you wanted a better and longer lasting finish for. Likewise, as a summer house roof covering, garden building or home office they are a great option as they provide considerably less rain noise than plastic roof sheets or metal roof sheets. If you did require natural light through the roof however, a PVC Clear Roof Sheet in a matching profile can also be provided to be installed as a Rooflight.
With the ability to be installed as low as a 5 degree pitch when roofs are fully boarded with OSB3 Board (or equivalent), these are also a low pitch roof solution so there is rarely a garden building project where they are not the best solution to achieve an attractive, fast to install and cost effective roof.
If installing on a larger roof like an Agricultural building or Garage roof where a slightly more heavyweight option may be needed, Onduline is a slightly heavier grade sheet than the Coroline as it is 3mm thick rather than 2.6mm on the Coroline. The sheets can also be installed vertically as Cladding for Agricultural buildings or animal shelters if required. Bitumen Roof Sheets can also be used for oversheeting on garages where the costs or risks of removing the current roofing is too high, many garage roofs are Asbestos and if the removal is too costly you can simply counter batten over the roof, then install Coroline or Onduline on top meaning the roof is fully secured and waterproof with minimal trouble caused by having to remove or dispose of the Asbestos sheeting.
A full range of accessories is also available to match both Coroline and Onduline Bitumen Roof Sheets as well. Ridge tile pieces are available in the full range of colours for covering the Apex of roofs where needed, but these are also flexible enough to be used as hip tiles down the hip of a roof where two pitched sides meet such as an L Shaped Barn. Right angled verge pieces can be used to create a neat finish down the verge of the roof (also referred to as gable end), this dry verge system can also prevent water ingress or pests entering at the gable ends. If required, the verge piece can also be bent round to form a mono pitch ridge if required for a single pitch or pent roof. If installing on a lean to or butting up to an existing building then an Apron Flashing is also available as part of the product range.
Fixing nails with waterproof caps are also sold as part of the system, fixed through the crown of the sheets into timber boards or battens they offer a secure and long-lasting fixings solution. If required eaves fillers matching the profile of the sheets are available to close off the eaves preventing draughts or wind uplift in exposed areas, or if you wanted to leave the eaves open for ventilation in a garage for example but wanted to prevent access for pests you can use a ventilator strip comb.

Tools required for installation and planning a job with Bitumen Roof Sheets.

  • Tape measure
  • Handsaw
  • Hammer
  • Ladder may be needed for roof access

Both Coroline and Onduline install exactly the same way, the only difference is the thickness of the sheets, you can find both the PDF installation guide and installation video below.

Click HERE to view the installation guide.


The side lap and end lap requirements are outlined simply in the below table.

Frequently Asked Installation Questions regarding Bitumen Roof Sheets

How many fixings will I need?
20 fixings are recommended per sheet and are provided in packs of 400 or 20. The 400 pack is very cost effective so advisable to purchase this to never be short of the fixings needed.

How much should you overlap the sheets on the width?
The sheets offer 855mm cover width per sheet, so you can easily work out how many to cover the width of your roof by dividing the total width in mm by 855mm, this will allow for ample coverage and allow for overlap.

If my roof is longer than 2m how much to do I lap the sheets end to end?
This depends on the roof pitch, for 5° to 10° the sheet end lap is 300mm, for 10° to 15° it is 200mm and for pitches above 15° it is 170mm.

How do you cut Coroline Bitumen Roof Sheets?
Sheets can be cut with a fine toothed handsaw.

Which way up do Bitumen Roof Sheets go?
The underside of the sheets has a rough surface which you should have facing down on the roof, the coloured surface is a smoother finish and would face outwards.

Can I install this roof system on my own?
The system is lightweight enough to install solo, but consideration should always be made for safety on site and no unnecessary risks should be taken.

Can you walk on Bitumen Roof Sheets?
No, they are not suitable to be walked on. If you needed to access the roof for maintenance it would be advisable to use a crawl board to spread the weight so as to not damage the sheeting.


If you have any other questions on Bitumen Roof Sheets and their uses please get in touch and we would love to speak with you to discuss your project and provide an estimate. You can get in touch by phone on 01752 466151 or by email on