Attached or freestanding is the first real decision, and it changes everything after it.
An attached pergola ties into the existing house structure, which can reduce the number of posts and footings needed but requires the connection to the house to be properly engineered and flashed to avoid weathertightness problems at the junction. A freestanding pergola avoids that connection risk entirely but needs its own full set of footings sized for the wind loading the structure will actually experience — which in more exposed New Zealand wind zones can be a bigger structural consideration than people expect from what looks like a simple garden structure.
Roof covering — solid, louvred/adjustable, or an open permeable lattice — is a genuinely separate decision from the structural question, and it's worth resolving the structure first, since it constrains what roof options are realistic.
01 · Structural decisions before style
Four factors that shape the structure.
Attached vs. freestanding
Attaching to the house saves on posts and footings but requires the house connection to be correctly engineered and weathertight — this is not a purely cosmetic choice.
Wind loading
Post footing depth and structural sizing need to reflect the site's actual wind exposure, which varies meaningfully across New Zealand and even within a single property depending on shelter from buildings or planting.
Roof permeability
A solid roof provides full rain protection but carries more wind load than an open lattice or louvred roof; louvred systems offer adjustable shade and rain protection at a higher cost.
Consent threshold
Whether a pergola needs building consent commonly depends on factors like size, roof coverage and whether it's attached to a building — this should be confirmed with the council rather than assumed exempt.
02 · Compare roof options
Solid, louvred and open lattice roofs.
Solid roof
Rain protectionFull protection in any weather
Wind loadHighest — needs correspondingly robust structure
LightFully shaded underneath
Louvred / adjustable
Rain protectionGood when closed, adjustable for sun and airflow when open
Wind loadModerate, varies by louvre position
LightAdjustable between full shade and open
Open lattice / rafters
Rain protectionMinimal — filters sun rather than blocking rain
Wind loadLowest of the three options
LightDappled shade, most open feel
03 · Two pergola briefs
Different exposure, different structure.
Attached pergola over a sheltered rear patio
Moderate wind exposure and an existing wall to attach to point toward an attached structure with a louvred roof, giving adjustable shade over a space that's already reasonably sheltered from wind.
Freestanding pergola on an exposed elevated deck
Higher wind exposure and no adjacent wall to attach to mean a freestanding structure with footings sized for that wind loading, likely paired with a more open roof style to reduce the wind load the structure has to resist.
04 · Before finalising a pergola brief
Confirm structure before style.
- Decide attached vs. freestanding based on the house connection and site layout, not just cost.
- Confirm footing specification reflects the site's actual wind exposure, not a generic assumption.
- Check the building consent threshold for the specific size and roof type with your council before finalising the design.
- Choose roof permeability based on the actual comfort problem (rain, sun, or both) rather than appearance alone.
Pergola planning: common questions
Does every pergola need a building consent?
Not necessarily — smaller, open structures are sometimes exempt, but this depends on size, roof coverage and other factors that vary by situation, so it should be confirmed directly with the council rather than assumed.
Is an attached pergola always cheaper than freestanding?
Often, because it needs fewer footings, but the connection to the house needs to be properly engineered and weathertight, which can offset some of that saving depending on the existing wall construction.
Can I add a louvred roof to an existing basic pergola later?
Sometimes, if the existing structure was built to handle the additional wind load a louvred roof introduces — this needs to be assessed rather than assumed, since retrofitting can require reinforcing the original structure.
Sources & methodology
Designed to show its working.
Pergola consent thresholds and wind loading requirements vary by council, size, roof type and site exposure. This guide is general planning guidance; confirm specific structural and consent requirements with a licensed building practitioner and your council.