Over-Sheeting a Thatch Roof

This roof conversion system involves cladding or over-sheeting the original roof with tiles or roof sheeting

Can you convert a Thatch Roof to another type of Roofing?

If this is the first page you’ve landed on you’re probably thinking about converting your thatch roof to another type of roofing. The good news is that you can! At Bosazza Roofing & Timber Homes we offer three different systems to convert thatch roofs: Structure Stays, Renovate/ Reconstruct and Over-sheeting. While we recommend using the Structure Stays system which removes all of the thatch from your roof, in some cases it is possible to over-sheet the original roof.

This article discusses the over-sheeting system in more detail. It also introduces some of the roofing products that we use for conversions.

To find out more about roof conversions and the other systems, visit our main page Thatch Roof Conversions >

Over-sheeting a Thatch Roof

When over-sheeting a thatch roof the original roof needs to be in a very good condition. What does that mean?

1. The thatch must not be showing serious signs of rotting
2. It must be totally dry without moisture in the layers of thatch
3. The thatch needs to be properly compacted
4. The roof structure needs to be strong and solid

If you are getting problems like dust falling from your roof, it is not in the right condition for over-sheeting because these problems will continue even after the roof is covered. In fact, it will be harder to attend to them after the roof is covered. You will be better to consider the Structure Stays system.

Pros and Cons of Over-sheeting

Pros:

• Less invasive
• Can be more cost effective
• Keep the look and feel of thatch inside

Cons:

• Doesn’t remove all of the thatch
• May still be considered a thatch roof by insurers
• More difficult to access thatch if there is an issue

Pros in more detail

Taking a look at the pros to start with, during the actual time of the conversion, the work is less invasive than the other conversion systems. That’s because the original roof is kept intact and the house is not open to the elements at any point.

This system can also be more cost effective because thatch is a great insulator. In systems where the thatch is removed totally, new forms of insulation need to be fitted to make sure that the roof is thermally efficient.

Keeping the original thatch roof also means that you can keep the look and feeling of the thatch roof on the inside. Let’s be honest – thatch has a look and charm of it’s own!

Cons in more detail

It’s also important to look at the cons of this system. You might be ready to remove the thatch and strip it completely; the over-sheeting system will not do this for you. As we mentioned previously, if you’re having issues with the thatch roof such as dust falling out of it, the over-sheeting system is not for you.

Some insurers may still consider the roof thatched if you still have the thatch layer so if you were looking for a reduction in insurance premiums, you will need to check with your insurer what their specifications are. Some companies specify that only a very thin layer of thatch can be kept. They may also require the application of a fire retardant. We would advise that if you’re planning on making any major changes to your roof, you should always contact your insurance provider to find out their requirements.

Finally, if there is any kind of issue with the thatch roof underneath the new roofing, it can be more difficult to access as it is covered with the new roof.

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

We currently use two different roofing products for thatch roof conversions. We have been converting thatch roofs for approximately 10 years and use these roofing products because they offer reliable, long lasting roofing solutions in a variety of harsh climates. They can also be installed successfully over thatch.

Our preferred roofing products are:

• Metrotiles
• Aluminum / Aluzinc roof sheeting

A note on choosing the new roofing: not all roofing products suit all roof shapes! Some thatch roofs are built with beautiful curves, smooth corners and contours. While these new roofing products have some degree of flexibility, there are not as flexible as thatch. You have to bear this in mind when choosing a new roofing product.

Currently our premium roofing product used for thatch roof conversions is asphalt shingles – please note that these can only be used when the thatch has been stripped off the roof entirely. Read our article about the Structure Stays conversion system to find out more.

Converting a Thatch Roof to Metrotiles

Metrotiles are a light-weight metal roof tile coated in stone. They are specifically designed to look like traditional roofing and blend easily into the surrounding environment. Metrotile offer a range of different tile profiles and finishes. We prefer to use the Woodshake profile when converting from thatch because the texture and shape of the tile imitates that of a thatched roof.

The Woodshake range is available in a variety of colors. We recommend using Pepper or Charcoal as these are neutral colors, similar to thatch when it is aged.

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

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

Why Choose Metrotiles to Convert your Thatched Roof?

• Close match in color 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, 40 years close to the coast)
• Weathers well as the product ages

Converting a Thatch Roof to Metal Roof Sheeting

Metal roof sheeting has made 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 roofing solution.

• 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.

Our choice of roof sheeting for many roofing projects is the classic corrugated profile from Safintra. The sheeting is made of aluminum-zinc (AZ) coated steel which is lightweight but strong, thermally efficient and fire resistant. The sheeting comes in various weights and thicknesses catering for both inland and coastal climates.

The roof sheeting is coated in Colorplus® which is the latest technology for pre-painting roof sheeting. The painting system is designed to ensure that the finish of the roof sheeting can endure the harsh African climates of both inland and coastal areas.

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

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
• Reflects heat and is thermally efficient
• Low maintenance
• Lightweight
• Suitable for inland and coastal climates
• Product has a warranty of up to 15 years

Your Choice of Roofing Product Depends on a few Factors

Ultimately the roofing product that you choose 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 can offer advice on which product would be most fitting for your roof. We are based outside of East London in the Eastern Cape of South Africa, and service roofs in the wider Eastern Cape area.

The Process of Over-sheeting a Thatch Roof

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 good condition to make this a viable solution. Covering rotten, old, dusty thatch will not stop it from deteriorating further and dropping more dust and debris in the home. We recommend using the Structure Stays system (find out more about the other conversion systems on our Thatch Roof Conversions page).

Preparing the Thatch Roof

The majority of thatch roofs will need some maintenance before over-sheeting. This could include brushing, compacting and re-tensioning of the thatching twines. Some insurance companies require the thatch layer to be a maximum thickness of 50mm underneath the new roof so the thinning of the thatch needs to be done before it is covered. Fire retardant spray can also be applied both inside and out during this preparation work.

Installing the Support Structure

We install a lightweight wooden structure over the thatch with specialist valley sections in the drainage valleys on the roof. Our preferred valley sections are made of a polypropylene composite which is lightweight, weather-proof and long lasting.

The process is the same for both round or curved roofs, and for roofs with more traditional straight angles, corners and edges. The wooden structure covers the roof and follows the shape as closely as possible.

Fitting the New Roofing

We install the new roofing on top of the wood structure; both Metrotiles and corrugated roof sheeting use specific fixings that match the roofing product.

The Finishing Touches

Once we have installed the new roofing over the whole roof, we add the finishing touches which includes the ridging, hip sections, painting of the fascia’s and fitting the gutters. All of the roofing products that we use come with matching ridges and hip sections which ensures that your new 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 and roof structure are in a good condition. We recommend using one of the two products discussed above: Metrotile or corrugated aluminum/ aluzinc roof sheeting. Your choice of roofing product may 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. In all cases, you should use a professional contractor to work on your roof.

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.

POST LAST UPDATED Jun 08, 2022