Roofing in Mpumalanga

Highveld hail: the record holder

When the researcher Olivier analysed South African Weather Service hail reports from 66 stations across the former Transvaal between 1962 and 1986, the highest point frequency of hail days turned up on the Mpumalanga Highveld. Hail there falls mainly between October and March, peaks in November, and is most common in the late afternoon. More recent University of Pretoria modelling shows large hail over 3 cm already reaching the eastern escarpment in October, earlier than most of the interior.

For a Highveld homeowner, that means:

• Get roof work done by September, before the storm season starts.
• After hail, check valleys and ridges as well as the main slopes, and photograph damage before anything is moved.

Lightning on the escarpment

The South African Weather Service's lightning climatology found the highest flash densities in the country along the northern part of the eastern escarpment, running from northern KwaZulu-Natal into Mpumalanga, and rated these slopes at extreme risk. Much of the Highveld and the escarpment records 10 to 15 ground flashes per km² a year.

That matters most for thatch. SANS 10400-T requires a lightning protection system, designed and installed by a competent person, on thatched buildings and lapas where the flash density exceeds 7. If wire sways hold the thatch down, the threshold drops to 3. Across much of the Highveld and the escarpment, a new or re-thatched roof should come with lightning protection on the quote.

Fire spacing for Lowveld thatch

If you own or are planning a thatched house, lapa or cottage, the fire rules are strict. As the Thatchers Association of South Africa summarises SANS 10400-T:

• A thatched roof with a plan area over 20 m² must be at least 4.5 m from any boundary.
• A thatched building closer than that, or with more than 300 m² of thatch, needs additional fire protection, such as a tested fire-retardant treatment, a fire blanket or a drencher system, maintained to the manufacturer's specification.
• Chimneys must rise at least a metre clear of the thatch and have a stainless-steel spark arrester.

Coal-belt air on the Highveld

A national corrosion study found increased corrosivity around Secunda and eMalahleni, two of the most polluted areas in South Africa, and linked it to the petrochemical plants and coal-fired power stations nearby. Across the Mpumalanga Highveld, mild steel corroded at an average of about 29 µm a year, in the moderate class and above the Pretoria average. Ask for coated sheeting and fixings rated for that environment rather than the cheapest available.