What to Know About Building a Pergola in Your Garden
From design choices to material options, check out this advice for adding a structure for climbing plants and shade
A pergola covered with plants, both on the exterior and hanging inside, is the very definition of a garden room. For avid gardeners, this makes a pergola the perfect spot to show off spectacular climbing or vining plants – anything from ivy and wisteria to roses and clematis. You could even add some edibles, such as tomatoes or grapes.
Here’s what to know about adding a pergola to your garden, including ideas for the design and location and the pros and cons of different materials.
A classic pergola’s design is deceptively simple. It consists of four posts, which in turn support four crossbeams or a mix of beams and rafters around the top perimeter of the structure. A slatted or lattice roof provides filtered shade.
A pergola has the look of an arbour and, like an arbour, is traditionally covered with climbing or vining plants. The primary difference between the two structures is size. Pergolas are designed as places for lingering rather than passing through, so they’re usually much larger, with dimensions similar to those of a gazebo or pavilion. Think of it as a hybrid of garden structures.
For most homeowners, hiring a landscape architect, designer or contractor is necessary for adding a bespoke pergola. Even with pergola kits, hiring a contractor is a good choice. For more extensive landscape projects, look for a landscape architect or designer. While the cost is higher, a professional can help you finalise your plans, including what will work best to provide the right blend of sun and shade.
Landscape professionals will also analyse your proposed site and do any necessary prep work; check you don’t need Planning Permission (most pergolas don’t, but some, eg in a conservation area, do); mark off water, gas and power lines, and coordinate workers. If you’re adding electricity for lighting, you’ll need a registered electrician. A professional should also be hired to install gas and plumbing lines, and to help with installing entertainment systems.
Read client reviews and see past projects for landscape contractors and gardeners in your area.
Before you consider this route, take stock of your tools and your expertise level. In addition to building, you’ll also need to take on the legwork of preparing the site and checking for gas and plumbing lines. Remember that much of your work will be done on the top of the pergola, and staying safe while working on overhead elements is essential.
Pergolas can be incorporated into almost any area of the landscape and can serve a variety of purposes. You can also adapt them to fit your personal style and preferred materials. Here are some things to consider when adding a pergola to your garden.
The size of the support posts and overhead pieces will affect the look of your pergola. Slender posts and beams, whether made of metal or wood, lend themselves to a more refined and less intrusive look. More robust posts will add more weight and presence, along with rustic appeal.
The spacing of overhead slats and how they’re set, whether horizontally, vertically or at an angle, will determine the amount of sunlight that reaches the interior of a pergola throughout the day. Moveable overhead slats or louvres can be adjusted to adapt to the available sunshine or even shut completely in case of wet weather.
Shade cloths and retractable canopies can provide additional overhead protection. For a more open, less confining feel, think about designing a gabled or arched roof, or even eliminating any sort of roof altogether.
Many people think of wood when it comes to pergolas, but your material options are surprisingly wide. Vinyl and fibreglass pergolas are lightweight and long-lasting options, as are aluminium models. Steel pergolas are heavier, but also a good choice to consider.
Choose from a softwood, such as pine (typically cheaper), pressure-treated with a preservative, or a naturally durable hardwood such as ipe or oak. Before you buy, check the wood is certified as sustainable by the Forest Stewardship Council (FSC).
However, while hardwoods can be painted, many people prefer to simply seal them to showcase their natural beauty.
You’ll also need to maintain that finish, resealing and staining every year or two and repainting every few years. Even with regular maintenance, you may need to make more extensive repairs after 10 years or so.
If you’re growing plants on your pergola, the moisture from the plants themselves, combined with their weight, can damage wood posts and overheads. Trim back the plants and check for signs of damage annually.
Vinyl pergolas come in limited colours – primarily shades of white – and can’t be painted. Their light weight limits their overall span, and they can sag under a snow load. They are usually freestanding.
Aluminium is a good choice for coastal locations, thanks to its resistance to rust. It tends to cost more than vinyl, but usually less than or equal to wood. One thing to know about an aluminium pergola is that its light weight means it has to be well-anchored in windy areas.
Steel is heavier, making it stronger and more impervious to weather. It can also span longer distances without needing supports, which is a bonus for larger installations. It falls on the higher end of costs for materials.
Both materials are strong and extremely low-maintenance, and are good choices for a range of climates. Wipe down finished steel or aluminium with a non-corrosive cleaner every year or so. That’s also a good time to check the connections on the pergola to be sure they haven’t loosened.
Whatever your pergola’s material or style, you’ll need to be sure its posts are securely anchored to the ground. Pergolas over decks and concrete slabs can be anchored with fasteners that are specifically designed for that purpose.
For other surfaces, including pavers, the posts will need to be set into the ground. This involves pouring concrete footers or installing anchors on a footing that can literally screw into the ground. If you live in an area that experiences freeze-thaw cycles, the posts will need to be set below the frost line. An experienced landscape contractor will be able to handle any of these installations.
As with any outdoor project, the best time to build is during good weather from spring to autumn.
How long will it take? Depending on the complexity and the amount of preparation needed, including time for setting concrete footings and staining or finishing the materials, it could take about a week to build a basic pergola (after you’ve got a landscape pro on board). If your design is more complicated or you’re installing amenities such as an outdoor kitchen or fireplace, expect a longer timeline.
Are you planning to construct a pergola in your garden? Did you find this advice useful? Share your thought in the Comments.