English oak, cedar or softwood - timber choice matters
English or European oak is my recommended timber for most pergola jobs. It's strong enough to allow elegant slim sections (150x150mm posts, 200x50mm beams), naturally weathers to silver-grey without treatment, and lasts 30-50 years. The cost is higher (£2,800+ for a 4m x 3m four-post pergola) but the aesthetic is unmatched.
Western red cedar is a beautiful alternative - lighter in colour, more workable, a slightly more contemporary feel. It's commonly used in Scandi-style garden rooms and is particularly well suited to coastal environments. Similar price bracket to oak.
Pressure-treated softwood is the budget option - from £1,400 for the same 4x3m pergola - but needs annual oiling or staining and has a working life more like 15 years. I'll happily build in softwood if budget dictates, but I'm always clear about the lifetime cost and maintenance commitment.
Design details - from simple to architectural
A simple 'four-post' pergola - four corner posts, two main beams, four cross rafters - is the classic garden pergola and gives just enough structure to support climbing plants and provide definition.
More elaborate designs include: roof rafters that step out beyond the outer beam (gives a 'Japanese temple' look); slatted roof infill for more shade (slats every 150mm rather than 400mm cross rafters); attached pergolas that tie into the house wall on one side; pergolas with integrated screen walls for privacy from neighbours; heated pergolas with infrared heaters tucked under the main beam for year-round use.
I fit louvred roofs for clients who want a fully weatherproof outdoor room - the louvres motor closed for rain and open for sun. Prices for louvred pergolas from around £7,500 including motorised drive and sensor.
Foundations, posts and wind loading
Southport's exposure to prevailing westerly winds off the Irish Sea means pergolas here need more substantial foundations than a typical inland site. My standard foundation for a timber post is a 600x600x900mm deep concrete pad, with the post either bolted to a galvanised post-shoe set into the concrete or set directly into concrete with a stainless post-saver sleeve.
Post-shoes are my go-to for most jobs - the timber post is held clear of concrete (so it can't rot at the base), the post-shoe is stainless or hot-dip galvanised (so it can't rust), and the post can be replaced in 20 years without digging out the foundation.
Cross beams are always properly jointed - through-tenons pegged with oak dowel in oak pergolas, or bolted lap joints in softwood pergolas. Never just toenailed or bracketed.
