Building construction: Roofing

29 Jan, 2023 - 00:01 0 Views
Building construction: Roofing

The Sunday News

Real Estate issues with Jonathan Thompson

The roof of a home is very important to the design and look of a house. A property’s value will increase tremendously with a good roof, and will decrease where roofing problems are evident. Normally, when you see a house in the distance, the first thing you will notice is the roof.

The legal requirements for a roof and for the supporting structure is laid out extensively in “The Model Building By-Laws”, Chapter 6, Part II. This gives a strict guideline to the construction of your homes’ roof.
The roof is made of two basic parts, the substructure and the covering. The substructure is built first, and it rests on the top of the walls of the house. The structure is made up of the trusses, rafters, purlins, and other supporting framework. The substructure has to be strong enough to support the roof above and the ceiling below. In Zimbabwe, substructures may be constructed from timber, wooden poles, or steel.

Steel or timber trusses are generally built off-site and are brought to the construction area already assembled.
Once the substructure is in place, it is then covered with the roof coverings. The roof must be secured in a way that it can withstand all climatic conditions, such as wind pressure, rain, wind suction, and changes in temperature. It is important to use flashing to keep any joints of the roof waterproof, especially in corners and around the fireplace.

IBR sheet

Roof coverings in Zimbabwe generally fall into one of three categories, namely tiles, sheets, or thatch. Roofing tiles may be ceramic or slate. In other countries, wood or asphalt tiles may be used, but they are not common here. Roofing sheets may be manufactured of asbestos, corrugated iron, IBR, Harvey Tile, or Chromadek. There has been some development in this area. In the past, corrugated iron sheets were used extensively. Advancement in the manufacturing of corrugated iron sheets led to IBR (Inverted Box Rib). IBR sheets were developed further into Chromadek sheets.

These sheets are often have the same shape as an IBR sheet, but are more weather resistant, are pre-painted, and can come in very long lengths. Because Chromadek sheets can be made in any length, only one sheet may be needed to reach from the ridge at the top to the bottom of the roof.
This reduces the number of connections, which is good since any connection can potentially allow moisture into the house. The final common roof covering is thatch. Thatching is a thick covering of straight dry grass. A thatched roof is often laid on top of a timber pole substructure.

Thatched roofs require regular maintenance, and may leak. They will also need to be combed or replaced from time to time. A thatched roof home will generally have no ceilings, and is cooler during the summer months.
Each type of covering requires a different minimum pitch, that is the angle of the roof. A more waterproof covering may have a lower pitch, but other roofs, like thatch, require a higher pitch. The higher the pitch, the quicker the rain water falls off the roof.
Each type of roof covering is attached in a different way and weighs different weights. The roof covering type will determine the strength and type of roofing substructure that may be used.

When you are building a home, getting to the roof brings such a sense of accomplishment, because you are nearly finished. From the outside of the building, the completion of the roof signals that your construction has nearly come to an end. Parts of the home now become useable. The end is in sight!
n Jonathan Thompson is a Registered Real Estate Agent who works in Bulawayo. He has more than 10 years of experience in Real Estate in the USA, and in Bulawayo.
He is the founder and the Managing Director of Thompson Properties (Pvt) Ltd.

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