Field Guide 03 · Open-air venues
The best places in Perth to host an outdoor event, and how to build one of your own
Kings Park lawns, river foreshores and garden amphitheaters all share a few design rules. Here is how we apply them to timber event pavilions, estate pergolas and outdoor stages.
What the best outdoor venues have in common
Ask anyone in Perth where to hold an outdoor event and the list is usually some mix of the same places: the lawns of Kings Park and the Western Australian Botanic Garden looking over the city, the Swan River foreshore, the winery gardens of the Swan Valley, and the old stone and limestone courtyards of Fremantle. On the other side of the world, a few miles from our mill, Longwood Gardens near Kennett Square fills the same role for southeastern Pennsylvania.
These places have very different climates, but the good venues solve the same three problems. Guests need shade or shelter they can actually stand under. The structure has to be open enough to feel outdoors. And it has to sit lightly in the landscape, so the trees and the view stay the main event. Timber frames are good at all three.
Read the climate before you draw the roof
Perth has a Mediterranean climate: hot, dry summers, mild wet winters, strong sun most of the year, and an afternoon sea breeze locals call the Fremantle Doctor that rolls in from the southwest on summer afternoons. Lancaster is the opposite in winter. Snow sits on roofs, the ground freezes, and summer brings thunderstorms.
A pavilion designed for one climate will not work in the other without changes:
- Hot, sunny sites want wide overhangs, a high roof so hot air can rise away from guests, and an open long side facing the prevailing breeze. Orient the ridge across the afternoon wind so it moves through the structure.
- Cold, snowy sites want a steeper pitch, heavier tie beams and closer purlins. Snow load sets the size of almost every roof member.
- Windy sites anywhere need serious attention to uplift. An open pavilion roof behaves a bit like a wing. The posts have to be anchored to footings that resist the roof lifting, not just pushing down.
Three structures for open-air events
The event pavilion
A covered hall with no walls, sized for dinners, ceremonies and markets. Most are built as a run of identical bents with bays between them. King-post bents are the economical choice up to about 36 ft of clear span. Where a client does not want a tie beam crossing the room at head height, we cut hammer-beam bents instead.
Because there are no walls, the knee braces do all the work of keeping the frame from racking sideways in the wind. We use longer, heavier braces on open pavilions than we would on an enclosed building, and we brace in both directions.
The estate pergola
A pergola is a frame with an open or partly open roof of rafters and purlins. It gives dappled shade, defines a space on a lawn, and carries climbing plants. Good ones are bigger than people expect. A 4 in. purlin that looks right on paper looks thin against the sky, so on estate pergolas we usually go up a size from what the loads require.
If you plan to grow wisteria or a grapevine over it, size the frame for the plant. A mature wisteria is heavy and wet in the rain, and it will find any loose joint.
The amphitheater shell
A small outdoor stage with a timber roof and back wall does two jobs. It keeps performers dry, and it reflects sound out toward the audience. A curved or angled back wall of solid timber, with a sloped ceiling over the stage, can noticeably help unamplified voices and acoustic instruments reach the back rows.
Seating works best on a rake, each row a little higher than the one in front. A natural hillside does the hard work for you, which is why so many garden amphitheaters are built into slopes.
How big should it be?
Event planners work from rough area per guest. These are common rules of thumb we use for a first sketch.
| Event layout | Area per guest | 100 guests needs about | A frame that fits |
|---|---|---|---|
| Standing reception | 6–8 sq ft | 600–800 sq ft | 24×30 ft, 3 bays |
| Ceremony, rows of chairs | 8–10 sq ft | 800–1,000 sq ft | 24×40 ft, 4 bays |
| Seated dinner, round tables | 10–12 sq ft | 1,000–1,200 sq ft | 30×40 ft, 4 bays |
| Dinner plus dance floor | 13–15 sq ft | 1,300–1,500 sq ft | 30×48 ft, 4 bays |
Add space for a bar, a band, catering and paths. Then check the result against your local building and fire code, which sets the real limits on occupancy and exits.
Detailing for weather
- Keep end grain off the ground. Posts stand on raised steel bases or stone plinths with an air gap, so water drains away and the end grain can dry.
- Plan for gutters, or plan for drip lines. An open pavilion without gutters needs a gravel drip edge where the roof water lands, or the lawn turns to mud by the second event.
- Choose the right species. White oak has good natural decay resistance in its heartwood. Douglas fir is stronger for its weight and straighter, but it needs to stay dry and well ventilated outdoors.
- Finish for the sun. UV greys any untreated timber within a season or two. That is fine if you like the silver look. If not, use a penetrating oil with UV protection and recoat on schedule.
- Hide the power. Run conduit for lighting and sound up a post before the frame goes up. Retrofitting wiring to a finished timber frame is never pretty.
From a favorite venue to your own
The best outdoor venues in Perth or Pennsylvania all start with someone standing in an open field and picturing a roof over it. If that is where you are, start with three numbers: the clear span you want, the bay spacing, and the snow or wind conditions where it will stand. Those decide the frame.