ROOFS
Project by JNA Thatching.
often used as the inner layer, while common thatching grass is chosen for the outer layer.
All grass must be mature when harvested, meaning they have lost all its seeds. Harvesting is done in winter when the grass is dry.
Design- how to do it right
Keep the design simple. The more complex it is, the more maintenance will be needed later. Make sure the contractor or engineer provides the thatchers with structural drawings. This helps avoid unnecessary guesswork and clearly states the amount of material required.
A thatched roof should have a minimum pitch of 45 degrees, and at least 35 degrees above dormer windows. The smoother a thatched roof, the more velvety its finish. The better the thatching area, the more effectively water will run off – and it will last longer.
Flashed areas and features that penetrate or interrupt the roof should be minimised. Chimney shafts should be designed to penetrate the roof at the ridge, thereby eliminating the need for back flashing. Soil vent pipes are best placed on external walls so that they penetrate the thatch near the eaves line.
Rainwater must not be allowed to flow from a high-level roof onto a lower-level thatched roof. Refer to your SANS 10407 table. The roof framing generally consists of chemically treated eucalyptus poles. Thatched roofs are constructed with dripping eaves, meaning rainwater gutters and downpipes are not fitted. Eaves overhang should be at least 650 mm, and there should be provisions at ground level around the building to prevent erosion caused by water dripping from the eaves overhang.
Care of thatch
Good thatch will not need frequent maintenance. Assess the condition of the thatch early on, and then suitable work can be organised as needed.
• Do not assume that materials slipping or a roof appearing untidy means it needs re-thatching. Similarly, do not think that a neatly finished roof with a well-made ridge pattern is necessarily in good condition.
• A thick thatch isn ' t always better- and vice versa.
• The lifespan of a thatch can be greatly extended with prompt and proper repairs.
• Avoid walking on the thatched roof and discourage others from doing so, unless it is necessary.
• Non-thatchers ' service personnel should not install netting, flashings, or other roof fittings without consulting an experienced thatcher.
• Keep TV aerial or dish installers away from the thatch best possible.
• Standing on or using ridges as working platforms, should be avoided.
• All roofs, whether covered with grass or not, serve as habitats for insects. Professionally fumigate each year to get rid of bugs and pests.
• If a thatched roof is to be fire retardant treated, many critical factors must be taken into account prior, as outlined by SA Thatchers.
For any alterations, consult the thatcher who is to carry out the thatching work, or someone with the appropriate experience, knowledge, and roofing expertise in thatching.
Overall, proper maintenance and repairs can greatly extend the lifespan of thatch.
Acknowledgement is given to the valuable input of The Thatchers Association of South Africa( www. sa-thatchers. co. za). Email admin @ sathatchers. co. za for information and a list of approved members.
98 summer 2025-26 | www. tobuild. co. za