Over-Sheeting a Thatch Roof

Our most popular thatch roof conversion system involves cladding or over-sheeting the thatch roof with tiles or roof sheeting.

Before and after picture of a large thatched rondavel which we converted to corrugated roof sheeting
Before and after pictures of a large thatched rondavel over-sheeted in corrugated roofing

This method of converting roofs is popular for a few reasons:

  1. It is the least invasive of our conversion systems because the new roof is laid over the original thatch. This means that most of the work is outside and that the house is not open to the elements at any stage in the process.
  2. It is the most cost effective system because the original thatched roof is retained; there is no need to build a new roof structure, to install extra insulation or ceilings.
  3. It keeps the rustic look and feel of thatch on the inside of the house.

When over-sheeting a thatched roof, the choice of what kind of new roofing you can use may be affected by the shape and style of the original roof design. I will use some of our recently completed projects to explain what roofing products are available and why you might choose them.

What Roofing Products can you use to Over-Sheet a Thatched Roof?

We use three different roofing products when covering thatched roofs. CEO Jonathan Bosazza has hand-picked these specific roofing products because they offer reliable, long lasting roofing solutions in a variety of harsh climates, and can be installed successfully over thatch. There are two tile options and one corrugated sheet roofing:

Over-sheeting a Thatch Roof with Tiles

Metrotile
Thatched roof in Hogsback, converted to Woodshake Metrotiles
This thatched roof in Hogsbcak, Eastern Cape was converted to Woodshake Metrotiles

Metrotiles are a light-weight metal roof tile coated in stone, designed specifically to look like traditional roofing which blends easily into the surrounding environment. Metrotile offer a range of different tile profiles and finishes but when converting from thatch, we like to use the Woodshake range because the texture and mould of the tile imitates that of a thatched roof.

The range of colours available in Woodshake Metrotiles
Woodshake Metrotiles are available in a range of colours, we recommend using Pepper or Charcoal for a thatched roof conversion as these are a natural looking colour that blend with the environment like thatch.

The tiles are pressed from high grade zincalume protective steel before being coated in natural stone chip. Metal tiles can be used to over-sheet thatch because they offer more flexibility than traditional cement tiles, they can be moulded to a more shapely roof. They are also much more light-weight so you can install them over the original structure without adding too much extra weight to the original roof.

Metrotiles are made from layers of zincalume and coated in stone chips
This image shows the layer composite of Metrotiles

The tiles are interlocking and overlap when installed which makes them very wind and water resistant. Metrotile offer a 40 year warranty on the product.

Why Choose Metrotiles to Convert your Thatched Roof?
Picture of metrotiles installed on a thatched roof
Metrotiles are a close match to the look of thatch and blend in well with the surrounding environment
  • Close match in colour and texture to your original thatched roof
  • High wind and water resistance
  • Offer some flexibility to accommodate curves in the roof
  • Lightweight
  • Suitable for coastal areas
  • Great product warranty (up to 50 years)
  • Weathers well as the product ages
Onduvilla Tiles
This thatched home in Knysna was converted to Onduvilla tiles in charcoal black
We converted this thatched home in Knysna in the Western Cape, to Onduvilla tiles

Onduvilla tiles are the premium tile range from the Onduline group, who offer a variety of roofing products. The tiles are made from recycled cellulose fibers which are impregnated with bitumen under extreme pressure and heat. The resulting tile is lightweight and flexible which makes it a great option for over sheeting thatched roofs, especially if the roof structure has lots of curves and rounded areas.

Onduvilla tiles are available in four colours - shaded red, shaded green, shaded brown and charcoal
Onduvilla tiles are available in four colours: shaded red, shaded green, shaded brown and charcoal

Onduvilla tiles come in a range of colours and are designed to have the shaded look and texture of tiles used in the Mediterranean. Our preferred colour choice when converting thatched roofs is the charcoal black which tends to fade a little after installation. Once faded it looks a very similar colour to a thatched roof.

Why Choose Onduvilla Tiles to Cover your Thatch Roof?
This thatch roof in Port Elizabeth was covered in Onduvilla tiles in the shaded brown colour
This thatch roof in Port Elizabeth, Eastern Cape, was covered in Onduvilla tiles in shaded brown
  • Tile can accommodate larger curves and shapely roof structures
  • Cost effective
  • Suitable for coastal environments
  • Metal and asbestos free
  • Corrosion resistant
  • Good product warranty (15 years)

Over-sheeting a Thatch Roof with Corrugated Roofing

This large thatched beach cottage was converted to corrugated roof sheeting
We converted this thatched beach cottage in the Dwesa Nature Reserve to corrugated roofing

We have seen a recent trend among our clients in choosing corrugated roof sheeting to convert from thatch rather than using tiles. Metal roof sheeting is making a come back in South Africa where it used to be considered unappealing and was used mainly for industrial buildings, it’s now considered an attractive, environmentally conscious and budget friendly roofing solution.

Our choice of roof sheeting for over-sheeting thatched roofs is the classic corrugated profile from Safintra. The sheeting is made of aluminium zinc (AZ) coated steel which is lightweight but strong, thermally efficient and fire resistant.


Fun facts about steel
  • Steel is a permanent material that can be infinitely recycled and is 100% recyclable without loss of quality
  • Recycling steel saves precious raw materials and minimizes energy consumption
  • Even steel made 150 years ago can be recycled into new products
  • Steel is considered to be one of the most innovative and sustainable man-made products of the 21st Century

    Facts cited from the World Steel Association.

The Colorplus® roof sheeting is pre-painted in the factory, this painting system is designed to ensure that the finish of the roof sheeting can endure the harsh African climate both inland and in coastal areas.

Cross section of the Colorplus® roof sheeting
A cross section of the Colorplus® roof sheeting

The sheeting is available in a wide variety of colours – the most popular among our clients is Thunderstorm grey.

Thatch roof which has been converted to aluzinc roofing
Thatch Roof Converted to Roof Sheeting in Thunderstorm Grey, Eastern Cape
Why Choose Corrugated Roof Sheeting to Convert your Thatched Roof?
  • Although the sheeting does not offer the flexibility to curve to shapely roofs, it looks great when installed on more traditionally shaped roofs and has real curb-side appeal
  • Cost effective
  • Reflects heat and is thermally efficient
  • Low maintenance
  • Lightweight
  • Suitable for inland and coastal climates
  • Product has a warranty of up to 15 years & an installation warranty of up to 8 years if inspected and approved by Safintra

Ultimately the roofing product that you choose to clad the old thatched roof depends on quite a few factors including the shape of the roof, the climate that you live in and of course, your personal taste. We offer advice on which product would be most fitting for each roof that we assess.

What is the Process when Over-sheeting a Thatch Roof to Tiles or Corrugated Roofing?

It is important to remember that not all thatch roofs are in the right condition to over-sheet. The thatch needs to be in a decent state to make this a problem free roofing solution because covering rotten, old, dusty thatch will not stop it from deteriorating further and dropping more dust and debris in the home. If the thatch is in a terrible condition we would recommend using a different conversion system such as “Structure Stays” (find out more about the other conversion systems on our Thatch Roof Conversions page).

In some cases the thatch roof may need maintenance before over-sheeting; this could include a mild brushing, compacting and re-tension of the thatching twine. Some insurance companies require the thatch layer to be a maximum thickness of 50mm underneath the new roof so the thinning of the thatch takes place before covering.

This thatched roof was brushed to thin the thatch and fix any rotten areas before it was covered
This thatched roof was brushed to thin the thatch and fix any rotten areas in the roof before it was covered

If required, fire retardant spray is also applied both inside and out during this time.

The Process of Over-Sheeting a Thatch Roof

Installing the Timber Support Structure

We install a lightweight wooden structure over the thatch. First the ridge and corners are fitted, followed by batons running vertically down the roof.The batons are held in place with hoop iron.

The ridge and corners are fitted with wooden batons, then the vertical batons are fitted to run down the roof
The ridge and corners are fitted with wooden batons first, then vertical batons are installed down the roof.

We fit specialist valley sections into any drainage valleys on the roof. Our preferred valley sections are made of a polypropylene composite which is lightweight, weather-proof and long lasting.

Polypropylene sections are fitted in the valleys of the roof to ensure clear drainage
Specially made polypropylene sections are fitted in the valleys

We then fit horizontal batons to the wooden structure which will hold the tiles or roof sheeting in place. Fascia boards are also added at this stage.

Fascia boards and horizontal batons are fitted to the wooden structure
Fascia boards and timber batons are fitted to the timber structure

The process is the same for both round or curved roofs, and for roofs with more traditional straight angles, corners and edges.

This is an example of a curved or rounded thatched roof with dormer windows. The timber structure is applied in the same way.
This is an example of a curved or rounded thatched roof with dormer windows. The timber structure is applied in the same way.
Fitting the New Roofing

The structure is now ready to be fitted with the new roofing.

We fitted Metrotiles to this roof in Hogsback, Eastern Cape
We fitted Metrotiles to this roof in Hogsback, Eastern Cape
This client in Knysna chose Onduvilla tiles to curve around the shapely roof structure
This client in Knysna chose Onduvilla tiles to curve around the shapely roof structure
AZ200 corrugated roof sheeting was installed on this roof in the Dwesa Nature Reserve
AZ200 corrugated roof sheeting was installed on this rondavel roof in the Dwesa Nature Reserve
Adding the Finishing Touches

Once the new roofing is installed over the whole roof, we turn to the finishing touches which includes the ridging, hip sections, painting of the fascias and fitting the gutters. All of the three roofing products that we use come with matching ridges and hip sections which ensures that your roof has a beautiful finish.

*A quick note that we always recommend painting the outside walls of the house when the roof conversion is completed as they can appear shabby in comparison to the new roof! We can quote to do this when we do the roof conversion.

In Conclusion

Yes! It is possible to cover or over-sheet your thatched roof with another type of roofing, as long as the thatch is in a good state. We recommend using one of the three products discussed above: Metrotile, Onduvilla tiles or corrugated roofing. Your choice of roofing product might be determined by the shape of the original roof structure so it’s best to ask advice from a professional thatching and roofing contractor if you’re unsure of what is the most suitable.

Are you thinking about a thatch roof conversion? Feel welcome to contact us or comment below and ask any questions that we haven’t already answered above.

Leave a Reply

Your email address will not be published. Required fields are marked *