A thatch sealer is a coating sprayed onto a grass or reed roof to help it shed water, slow weathering and hold back moss, algae and fungal rot. It is not a waterproof skin: the pitch and thickness of the thatch keep the rain out, and a treatment helps the surface stay in good order for longer. Results depend on the product and the roof. Tell us about your thatch, and we pass your request to independent applicators and suppliers who quote you directly.
Types of treatment
- Water repellents make water bead and run off the surface so the outer grass dries faster.
- Preservatives help slow decay of the grass.
- Anti-fungal treatments hold back moss, algae and lichen on damp roofs.
- Some products combine these, and some also claim a fire retardant effect.
Ask what each product does, how long the maker says it lasts, and whether it is safe for nearby gardens, ponds and pools.
When to treat a roof
The usual times are on a new roof once the thatcher has finished, or on an older roof after it has been cleaned and repaired. Treating over moss, leaves and loose grass wastes product and traps dirt. Thin or worn patches should be topped up first, because a coating does not fix a roof that is already letting water in. Pick a dry spell: the thatch needs to be dry going on, and rain soon after can wash the product off.
Shade, damp and where it helps most
Roofs that stay wet gain the most: the south side, roofs under trees, roofs in humid coastal air and in misty mountain areas. Cutting back overhanging branches and clearing valleys of leaves helps as much as any product, because sun and moving air are what dry a roof. A treatment is part of good maintenance, not a stand-in for it. On a roof in full sun on the Highveld, where the thatch dries quickly after a storm, a sealer may matter less than keeping the ridge and valleys in good order, so ask the applicator honestly whether your roof needs one.
Colour change and re-application
Some sealers darken the thatch slightly or give it a richer colour at first, and some leave it looking much as it was. Ask to see a roof treated with the same product. Every treatment wears off with sun and rain and needs re-application at the interval the maker gives. Coverage in litres per square metre also comes from the maker and depends on how thick and dry the thatch is, so ask the applicator to show how they worked out the quantity. Keep a note of the product and the date, so the next applicator knows what is already on the roof and does not use something that clashes with it.
What to put in your request
- The roof area in m² and the type of thatch
- Whether the roof is new or recently cleaned
- Any moss, algae or damp areas
- Whether you also want a fire retardant
- Nearby ponds, pools or gardens to protect
Thatch Sealers and Treatments for homes, lodges, farms and venues
- Homeowners: treating a cleaned roof that sits under trees or faces south
- Estate homes and HOAs: keeping roofs in similar order where estate rules care about the look
- Game lodges and bush camps: slowing moss and rot on chalets in humid bush and under big trees
- Guesthouses and B&Bs: treating cottage roofs after cleaning so they look tidy for guests
- Farms and smallholdings: protecting farm lapas and rondavels that are hard to re-thatch often
- Restaurants, pubs and beach bars: treating thatch over terraces where a damp roof drips on tables
- Resorts and holiday parks: a rolling treatment plan on humid coastal units and gazebos
- Wedding venues, schools and churches: treating a wedding lapa roof before the busy season
- Builders, architects and developers: a first treatment on a new roof as part of the handover
Frequently asked questions
Do you treat thatch roofs yourselves?
Will a sealer stop my roof leaking?
Can I spray a sealer myself?
Does a sealer replace a fire retardant?
Thatch Sealers and Treatments by province and city
- Johannesburg
- Pretoria
- Centurion
- Midrand
- Sandton
- Randburg
- Roodepoort
- Krugersdorp
- Randfontein
- Germiston
- Boksburg
- Benoni
- Kempton Park
- Alberton
- Vanderbijlpark
- Vereeniging
- Durban
- Pinetown
- Pietermaritzburg
- Richards Bay
- Newcastle
- Ladysmith
- Gqeberha (Port Elizabeth)
- East London
- Kariega (Uitenhage)
- Mthatha
- Cape Town
- Bellville
- Paarl
- Stellenbosch
- George
- Worcester
- eMalahleni (Witbank)
- Middelburg
- Secunda
- Mbombela (Nelspruit)
- Rustenburg
- Brits
- Klerksdorp
- Potchefstroom
- Mahikeng
- Polokwane
- Tzaneen
- Kimberley
- Upington
- Bloemfontein
- Welkom
- Sasolburg