Rafter spacing is one of the most important things to consider when building a roof, and if you’re mapping out a project, you’ll likely hear about it. It can literally make or break your roof structure, so it’s essential that you carefully plan around it.
This is your one-stop guide to rafter spacing. We go through all the ins and outs to help you get it right, like what rafter spacing actually means, why it’s so important, standard spacing guidelines, how to avoid common mistakes, and so much more.
What Does Rafter Spacing Actually Mean?
If you’ve heard the term’ rafter spacing’ thrown about but don’t actually get what it means, we’ll explain.
A rafter is a key ingredient in creating a sturdy roof structure. It’s basically the timber skeleton that makes up the roofing framework. Rafter spacing is essentially the horizontal span that’s measured between one rafter’s center to the other. Rafter spacing is used to help roofers figure out how many rafters they need to support the roof structure and how much weight the roof can safely handle.
Why is Rafter Spacing So Important?
Rafter spacing is one of the most important things to get right when mapping out a roof frame. It gives you an accurate idea of the maximum weight your roof can handle, going hand-in–hand with picking the right materials for your roof, like clay tiles or metal sheets.
It also helps keep sagging and structural damage from happening over time. It also has a part to play in insulation and ventilation as it sets up the available airspace in your roof.
How To Calculate Rafter Spacing
Before you crack on, you’ll need to check your local building codes and regulations because these can affect how far apart you’re allowed to space rafters. On average, a span of 450mm up to 600mm is usually permissible.
When measuring, it’s standard to go from center to center, rather than edge to edge, because it keeps all the spacing uniform, making sure the roof can bear the right amount of weight.
The perspective tables you get when planning your roof structure are the best guide when determining rafter spacing because they show what the safe load limits are.
Rafter Spacing Guide
As a rule of thumb, the heavier the roofing, the closer together the spacing needs to be, whereas lighter roofing requires wider spacing. Here’s a general guide to help you figure out what kind of rafter spacing your roof needs:
450mm Spacing (centre to centre)
This is a standard span for heavier roofing materials, like slate and terracotta tiles. With a narrower distance, it gives an extra bit of umph to your roof. It’s a go-to spacing choice for steeper pitches, too.
600mm (centre to centre)
When you’ve got lighter materials on your roof, like aluminium roofing or concrete tiles, wider spacing will do just fine. 600mm is a popular option for standard suburban Aussie homes where the roof load is relatively moderate.
300mm (centre to centre)
300mm is usually picked for specialised roofs with extra needs, like added reinforcement. If your home is exposed to high winds and heavy snowfall, then this spacing is the best, and safest, choice that will ensure your roof stays intact and your home protected.
Common Rafter Spacing Mistakes (And How To Avoid Them!)
Roof rafter spacing is no beginner DIY endeavor. It requires a decent amount of expertise and meticulous planning. If you do try to take on rafter spacing yourself, you’ve got to ensure you get every detail right because the smallest flaw can coat you an entire roof!
To help you out, our expert roofers have gathered the most common mistakes they come across when working on roofing projects and shared the best way to avoid making them. Check them out right here:
Measuring Edge to Edge: Measuring from edge to edge instead of centre to centre will lead to structural troubles and even misalignment, so make sure you don’t make this mistake!
Going for the Wrong Spacing: Spacing your roof without thinking about how much weight it needs to bear, the kind of materials that will go on top, and how local weather (like snow or high winds) will affect it is a major rookie error. When in doubt, consult with a pro and double-check the perspective tables to inform your plan.
Forgetting to Check Local Building Codes: If you forget to check your local region’s building rules and regulations, and go ahead with building your roof, you might run into some legal troubles down the line. If you aren’t sure, you can always get in touch with your local government and ask.
Leaving It Up to Guesswork: Playing the guessing game will cost you a sturdy roof. Rafter spacing is all about accuracy. Don’t just measure once; you’ve got to be thorough. Instead, take 2 to 3 measurements and call on a qualified professional if you’re ever unsure about something.
Getting Equipped for Rafter Spacing
You’ll need the right supplies for the job, when taking on rafter spacing, like a spirit level for accurate horizontal alignment, a measuring tape that’s long enough to span the distance between rafter placement, rafter span tables, a trusty calculator for accurate measurements, and of course, safety gear (like protective gloves, a hard hat, and non-slip work shoes).
Once you’ve completed your roof structure and finished it off with your chosen tiles, you’ll need to look after it from the inside out. For essential maintenance and repair supplies, Evo Build is your one-stop shop. We’ve got a whole catalogue of roofing must-haves, including premium flashing, specialist solutions, and handy tools.
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Frequently Asked Questions
Is Rafter Spacing a DIY-Friendly Job?
It’s definitely not beginner-friendly. But if you’re up for a more complex DIY job and have the right level of knowledge and understanding about rafter spacing, then you could certainly try to take it on yourself. Just make sure you always check in with a professional if you’re ever unsure about anything before going ahead with construction.
What Is the Code for Rafter Spacing?
There’s no generic code for rafter spacing because it varies by region. For the sake of safety and legality, it’s important to check with regulatory bodies, like the National Constitution Code (NCC).
Are Rafters and Trusses the Same Thing?
Nope, they’re two different things. Roof rafters are singular beams that get measured and fitted on-site, whereas trusses are pre-constructed frameworks with a triangular shape that provide full roof support.