Roof space ventilation is the most effective and economic method of keeping harmful condensation to a minimum, and it can be achieved by providing eaves through to the ridge ventilation. The British Standard Code of Practice (BS 5534) specifies two ways of installing slates: nailing or hook fixing. These fasteners fix the slates to either batten, which is by far the most common English method, or to sarking board, which is commonly used in exposed areas in Scotland. If slates are machine holed it is recommended that only one slate be holed at a time. If the machine uses a punching method then attention should be paid to the risk of damage.

The type of slate depends on the pitch of the roof. For example, small slates are more suitable for steep roofs with free-flowing drainage whereas larger slates are a better choice for lower roof pitches with more exposure. In general any area within 30 miles of a west facing coastline is considered to be one of severe exposure. All natural slates can be fixed using slate hooks. The hook method offers considerable freedom in design and can save up to 25% on labour costs and eliminate breakages. The practice is very popular in Europe and is gaining popularity in the UK. To hole a slate with a spike hammer, position the slate flatly over a narrow iron. When measuring the position of the holes ensure the thinner end of the slate is at the top when fixed. This CPD will examine the strengths of this ubiquitous material and its suitability for roofing and cladding purposes, as well as going through the steps that are needed to ensure quality is maintained from source to the end result. Sourcing and quality

With the hook fixing system, the slates are secured at the tail, thus providing strong resistance to wind uplift. To comply with BS 5534, hooks should be stainless steel, 18/10 or 316 (marine) grade, 2.7 mm gauge and at least 5 mm longer than the minimum lap required.

There are a number of advantages and disadvantages which one should consider before using natural slate. On the plus side, natural slate has an aesthetic appeal and will stay looking good for many years. As such it may not need replacing. Other types of roofing slates such as concrete will lose colour and not wear so well visually, making slate more cost effective.The Hall Hook is a permanent, secret and fail safe device that should be used when replacing a broken slate. Each slate is held in place by four slate hooks – one at the head, one at the tail, and one on each side. The one at the tail prevents the hook from sliding down, the side hooks stop it from turning, and the one at the head holds it at the batten. There are two type of Slate Hook, an over batten type and a drive in type. The use of over batten type is very limited with the majority being drive in type (shown in picture). The head of the slate should lay approximately halfway on to the batten (i.e. 25mm on to the batten) leaving 25mm to nail into. A clearance of 6–12mm is recommended. So after experimenting with all manners of ideas and devices, Jimmy solved the slate roof repair problem with the invention of the Hallhook.