Are you looking to re-roof your home or working on a new build project? Knowing how many slates you need is one of the first and most important steps. Getting it right means less waste, fewer delays and a more accurate budget. If you get it wrong, you could face material shortages mid-project or overspend on surplus stock.
In this blog, we will explain how to calculate the number of roofing slates required based on your roof type, project size, roof pitch, and allowances for waste. Whether you’re a homeowner planning your first roofing project or an experienced tradesperson looking for a refresher, this guide will help you become more confident and make informed choices.
The number of slates you’ll need isn’t a fixed figure; it depends on several factors. Let’s break them down so it is easier to understand.
The size of slate you choose affects how many are needed per square metre. Larger slates cover more area, so fewer are required. In comparison, smaller slates offer more detail but require a greater number to be used.
For example, 600mm x 300mm slates typically require approximately 13 slates per m², and 500mm x 250mm slates require closer to 20 per m².
Roof pitch plays a crucial role in determining the correct headlap, which is the amount by which each slate overlaps the one below. A steeper pitch typically requires less headlap, while shallower roofs need more to prevent water ingress.
Things to consider:
Knowing your roof pitch helps you choose the correct headlap, which in turn determines the number of slates you need.
The headlap is crucial for water tightness. It also impacts how much of each slate is exposed. Once installed, it alters the number of slates needed per square metre. For example, if two roofers are using the same size slate but different headlap sizes, one uses a 75mm headlap, and the other uses a 100mm headlap, the roofer using the larger headlap will need more slates to cover the same area.
If you’re unsure how to calculate your headlap, our team is available to assist you and provide advice and recommendations. Alternatively, you can download a slate sizing and coverage guide for a quick reference.
Once you’ve chosen your roof slate size and confirmed your roof pitch and headlap, you can then start calculating how many slates you’ll need. Here is the method:
So, for example, if your roof is 100 m² and your chosen slate requires 20 per m², you’ll need 2,000 slates.
It’s important to order slightly more slates than the exact number needed. You might be wondering why. Well, during installation, some slates may be lost due to cuts, breakages, and offcuts around roof features like valleys and chimneys.
We recommend around 5% extra on straightforward roofs and 10% extra for more complex designs. This ensures that you won’t be caught short during installation, especially if your slate is a natural product with colour variation, as matching batches later can be challenging.
Slates are the main roofing material, a complete slate roof also includes:
These materials also impact how the slates are laid out, so it’s important to factor them into your planning. Our team are here to advise you on what’s needed for a complete and compliant installation.
If you’re unsure where to start or confused about how much slate you need, as the calculation is too difficult, don’t worry, you’re not alone.
At UK Slate, we’ve supported many roofing projects, and we’re always happy to advise on the right slate for your project, quantities, fixings and more.
Natural slate is one of the most durable and aesthetically pleasing roofing materials available on the market, and at UK Slate, we supply only the highest-quality slates from trusted quarries across the UK and Europe. Whether you’re looking for Welsh slate, Spanish Slate, or any other type of slate, we offer a wide range of options to suit every project and budget.
If you need further help with your roofing project, we’re here to help. Contact us today to discuss your project and receive advice on the number of slates you’ll need. If you’re confident in your calculations, then browse our full range of roofing slate and order online today.
Natural stone adds a natural style and sophisticated aesthetic to any home. However, as we approach the colder months, we here at UK Slate know that it can feel impossible to keep warm. Stone has a natural habit of being a bit chilly in winter due to its high thermal conductivity. However, this is something that can be used to your advantage with some smart thinking.
So, what is the best way to warm up the slate throughout your home to enjoy it year-round?
Underfloor heating is one of the most cost-effective heating solutions on the market today. Depending on the size of your home and your energy use, which fluctuates throughout the year, you could save as much as 50% of your heating bill—a staggering saving even when compared to the initial costs to install.
Slate naturally transfers heat effectively and efficiently. This means that your floors will stay warm throughout winter, gently heating the rest of your home. Heat rises, so having the source of your heat on the ground floor will increase its effectiveness.Â
The kitchen serves as the heart of the home, especially during the colder season, where stews and hearty meals are being cooked. While a rug might not be the most practical or sensible option for keeping your feet warm on cold floors, it is essential to consider the flooring choice during renovation projects.
For spaces with stone flooring, pre-planning is crucial to ensure comfort and aesthetic appeal. Additionally, certain areas, such as bathrooms, may not be well-suited for rugs, highlighting the importance of selecting appropriate materials for each space during your design process.
If you’re seeking slate suitable for underfloor heating, consider Elterdale Grey-Green Riven or Ravendale Graphite Riven. Both have a natural riven surface that offers excellent anti-slip features, making them ideal for kitchens or entryways. Elterdale features a warm earthy tone that complements various decor styles, while Ravendale boasts a sleek, modern dark finish.
Remember to seal your slate before use to prevent stains and simplify cleaning. Both options provide comfort, style, and safety for your space.
When comparing the effectiveness of underfloor heating to traditional heating methods in colder climates, it’s important to consider the way each system distributes heat. Underfloor heating provides a more even heat distribution across the floor surface, which can result in a more comfortable environment overall.
In contrast, traditional heating methods, like radiators, may create hot spots and cold areas in a room. Underfloor heating utilises the thermal properties of stone to maintain a consistent temperature, which can be particularly beneficial in areas with natural materials like slate.
In rooms such as your living room, underfloor heating is not always necessary. A living room is often the home of a fireplace, which can provide a perfectly natural way to heat your slate flooring during winter. Additionally, UK Slate specialises in bespoke slate hearths, allowing you to customise the look and functionality of your space while complementing the warmth from your fireplace.
The warmth from the fire will transfer to the slate flooring, creating a cosy atmosphere. It will not concentrate in one area as you may fear, as the heat will spread through the conducting nature of natural stone. This means you will have a toasty floor whenever you light the fire, lasting for hours – which is bound to happen almost daily during the winter months.
The most obvious free source of heat energy (although debatable at times in the UK!) is, of course, the sun. Internal slate window sills can be a great way to draw this warmth into a room on sunny days. As with slate flooring, these will hold their heat for hours after the sun has set, providing a warm bench to sit on and warm up on cold, frosty days.
Combining slate flooring with other heating elements can work quite effectively. For example, radiators can be used alongside underfloor heating, allowing for a multi-layered heating approach. This can be especially useful during extremely cold spells when additional heating may be necessary. It’s important to ensure that the heating systems are compatible and that the slate can handle varying temperatures without causing damage.
Additionally, using a fireplace in conjunction with underfloor heating can enhance the overall warmth in the living space, as the radiant heat from the fire can elevate the temperature of the slate flooring, amplifying the comfort provided by the underfloor system.
Ultimately, using slate and other natural stones does not mean you will have cold toes this winter. By planning ahead and considering the heating options, you can enjoy your natural flooring all year round, feeling prepared for the colder months.
If you would like more information about our bespoke slate products and how they can improve the aesthetic of your home or business, you can contact us at any time or call us on 015395 59289 to speak with our friendly team. To keep up to date with all of our latest news and updates, you can also follow us on Facebook, X and LinkedIn.
This interactive tool considers key specifications such as shape, material, dimensions, and finishing details to generate a personalised quote tailored to your needs. We offer a wide range of shape options, from classic rectangular designs to sleek, modern curves, all crafted from luxurious, high-grade slate.
This interactive tool considers key specifications such as shape, material, dimensions, and finishing details to generate a personalised quote tailored to your needs. We offer a wide range of shape options, from classic rectangular designs to sleek, modern curves, all crafted from luxurious, high-grade slate.
