BEFORE YOU START

Checks, preparation and the tools you will need

Start by confirming you are happy to erect a structure of this size in your garden and, where relevant, check if you need permission. It's also a good idea to consider your neighbours before any work begins. Make sure the finished height will not obstruct your view or your neighbours’ view, and if the pergola is being constructed near a property, plan the area so rainwater runoff slopes away from the building.

Next, check for utilities and any drainage problems before you dig. Take time to clear the base area properly so you are working on stable ground. Remove grass, rubble, and anything else that would stop you from setting out accurately.

Tools required   

Finally, gather your tools before you begin and keep them within easy reach. A basic kit typically includes a spirit level, tape measure, string, plumb line, screwdrivers, hammer, and a shovel or post hole digger for the posts.

Once you have everything on site, lay out all the project parts so you can identify each piece clearly and confirm you have the correct fittings. Wear suitable protective clothing throughout, including sturdy work boots, gloves, and goggles where appropriate.

Step  

Begin by marking out your footprint. Set out the four corner positions for your pergola and check the layout carefully before digging. Make sure the shape is square and aligned correctly within your garden space, especially if you are positioning it alongside a patio, fence, or pathway. Dig your post holes and fix the four posts in place. Many customers choose to use the high-performance concrete PostMix to help secure the posts firmly in place.

Step  

Once the posts are set, fix the two main beams across the tops of the posts to form the main frame. Positioning will depend on your design, but take time at this stage to level the front and back of the frame so everything is square and consistent before you build upwards.

Step    

At the frame level, fix the top rafters evenly spaced across the main beams. This creates the main run of timbers across the top of the pergola and sets the look of the finished structure, so it is worth measuring the spacing carefully for a clean, balanced finish. Some customers, for instance, prefer a tighter spacing for a more enclosed look, while others leave wider gaps to allow more light through.

Step 

To add rigidity, fix diagonal braces into the corner positions where the posts and beams meet. These bracing pieces help the structure feel tighter and more stable, particularly once the pergola is exposed to wind and changing weather.

Finishing touches and protection

Once the pergola is assembled, a considered finish can make a big visual difference, especially if the structure is a focal point in the garden.

If you are planning to paint, choose a product designed for timber and exterior performance. Our Thorndown Wood Paint range is water-based, low odour, and hard-wearing, with a wide choice of colours if you want something softer than a standard brown treatment.

If you are building from scratch, selecting straight, graded timber for posts and main beams will also help the final structure look cleaner and stay true. You can browse suitable options in our construction timber range and choose sizes that match your design and loading requirements.