If you want to install your own slate roof it is highly advisable that you do some research in advance. Preparation is the key to success, so before you start make sure you are knowledgeable about slate types, their manufacturing techniques, sheathing, flashing, nailing and materials as well as slate roofing tools.
First of all, check that your roof is suitable for the installation of a slate roof. Slate roofs should not be installed below a slope of 4:12 (4 feet of rise on 12 feet of run). If your roof meets this requirement, give some thought to acquiring appropriate slating tools and to buying the slates and other materials you will need for the job.
Tools
Get the correct slating tools and use them. Your basic toolkit should consist of a slate ripper, a slate cutter and a slate hammer. When cutting slates, use a slate cutter not a diamond Roofing Industry Market Size saw. The former will create a bevelled edge on the slate which matches the look of all other slates, whereas a diamond blade produces a square edge which looks out of place.
Slates
Not all slates are created equal and you want the right slates for your roof. When choosing slates consider the type, quality, size and thickness and their implications for your work. For example, thick slates are harder to cut while small slates take longer to install as there will be more of them.
Make sure the slates have the nail holes in the right place. The holes should be positioned in such a way that you can get the nails in just above the head of the underlying Commercial Roofing Checklist slate. If the nail holes are too low, you’ll be nailing right through the head of the underlying slate and you should never do that as it can create leaks.
Order the right quantity of slates. You should work out your head lap in advance and order enough slates to accommodate this. It is best to order starter course slates separately. You want the nail holes for your starter course only along the top and on the front of the slate.
Materials
Slate Nails
Use good nails. Slate nails should be aluminium or stainless steel. In coastal areas copper nails are preferable and in severe conditions silicon-bronze nails are best.
Use the right nail length. Your nails should just penetrate the roof deck boards when installing them. This is important because if the they are too long, they will go right through the boards, breaking and splintering the wood at the back. This will reduce the boards’ thickness as well as the holding power of the nails.
Decking materials
The decking materials under the slate must last at least as long as the slates themselves, so you need to choose materials that are durable enough. Tried and tested materials that meet this requirement include wooden boards and battens ranging from 20 to 40mm in thickness. They may be rough-sawn, planned or of tongue-in-groove type. Other durable decking materials are concrete that can be nailed and gypsum. Avoid plywood or laminated wood.
Underlay
Slate roofs don’t really need underlay. Underlay essentially just has to keep out the water until the slate tiles and the flashings are installed. It also provides a surface for your chalk lines. A single layer of 30lb felt is sufficient in most cases.
Flashing material
Use good flashing material. Copper, stainless steel or sheet lead are all suitable. The material you use should be heavier on valleys and gutters than on ridges or chimney flashings.
If you give sufficient consideration to all these matters, you will be well prepared for the actual installation of the roof.
