How Many Roof Tiles Do I Need?

When installing a new roof, or replacing an old one, one of the major purchases is the tiles and it’s important to buy an accurate quantity for your needs.  Too few and your job will be left unfinished, possibly compromising the schedule,  not to mention that the roof will be left open to the elements.  Too many and you will have wastage and this can compromise the budget.  Making an accurate calculation and ordering the right amount is key to the overall success of the job.

Factors to consider when ordering tiles

Tile Size - you may be surprised to know that tiles come in various sizes, so naturally your choice of tile will affect how many you need to purchase.  Larger tiles will cover a wider area than smaller tiles.

Headlap - each type of tile comes with a specification of how much overlap is needed to the next tile, this overlap or ‘headlap’ eats into the area each tile will cover.  The larger the headlap, the more tiles you will need.

If this is starting to sound complicated, don’t worry, tile manufacturers simplify the process by stating how many tiles per square metre you need.  This means, you only need to calculate how many square metres you need to cover.

How to measure your roof

This is the calculation you require to measure your roof: 

Roof width (m) x roof slope height (m) = half roof area (m²)

Take the roof width and multiply it by the slope height.  This calculation will give you half the roof area, so then simply multiply by 2 to give you the area of both sides.

You now have the area of your roof in square metres.

How many tiles do I need

Now find the tiles you want and the manufacturer’s specification for how many tiles per square metre you need, and then simply calculate as per below.  Let’s say the manufacturer’s recommendation is 20 tiles per square metre.

Roof area (in square metres) x 20 = Quantity of tiles

Marley Eternity Tiles

These are the details for the popular Marley Eternity range of tiles.  So for example, if you required 3200 tiles for your roof, you now know you need to order three pallets.

How Many Redland Tiles Do I Need?

Here are the details for some of the most popular Redland tiles;