Blog

29 Jun

Why Good Process Matters

Here at JRC we talk a lot about the importance of maintaining good processes when it comes to our slate. Grading all slate and properly planning out the roof you’re about to lay are common themes in our advice to clients. We don’t just say it because we like the sound of our own voice – a properly-done slate roof can last over a century. A poorly-done roof, on the other hand, is liable to start breaking down sooner rather than later.

Grading slate is a simple, straight-forward task – organise the slate into three or four groups of similar thickness. As natural slate is hand-split, there’s guaranteed to be some variation in thickness throughout. This isn’t actually a bad thing, as we’ll soon see. When laying the slate, put the thicker, heavier slates at the bottom – this means that the extra weight receives greater support from the walls.

The benefit of putting these thicker slates at the bottom is that the bottom of the roof is the area that sees the most exposure to weather. These thicker slates will resist the eroding effects of rain and shine better than thinner slates. You’ll also find that grading the slates leads to a more pleasing finish on the roof, as each course of slate looks neat and tidy.

Another key process to maintain when laying slate is keeping a good headlap. Headlap is when the top of a slate (the “head”) is overlapped by the slate two courses above it. This is essential to ensure that the roof is watertight – without headlap, the roof will leak. Generally, the amount of headlap required will vary between 70-100mm. However, different roofs in different environments will need a different approach.

The amount of headlap needed is affected by a variety of factors, not least the amount of exposure you expect the roof to endure. The pitch of the roof, the slates being used, and the location of the project are all vital factors also.

As a rule of thumb, if you’re not 100% sure what amount of headlap to use, it’s best to get in touch with the distributor who provided the slate, as their experts will have the technical knowledge necessary to put you on the right track. There’s simply too many variables at work to be able to say with confidence what amount of headlap is necessary without a full knowledge of the project at hand.

To find out more about the services JRC can offer alongside their superb slate service, please contact us today.