Ideas Library · Exterior
Open Joints: Letting the Gap Read as a Dark Line
On a drained facade the open joint is deliberate, because the layer controlling water sits behind the cavity rather than at the face. Treating that gap as a design element — its width, its rhythm and the darkness behind it — turns a technical arrangement into the elevation's main line.
Spaces:house facadeextensionoutbuildinggarden roomupper-floor facade
Style:contemporarylayeredcrisptechnical
Where this idea works
Where this idea works
Contexts this direction tends to suit — and, honestly, where it may not.
- Drained and back-ventilated facades where the control layer sits on the backing wall
- Panel or board cladding where the joint rhythm could carry the elevation
- Elevations where a crisp, layered reading is preferred to a continuous surface
- Walls where the backing can be finished and detailed to be seen through the gaps
Where it may not fit
Where it may not fit
- Facades whose outer face is relied on to exclude water, where an open joint is a defect rather than a decision
- Walls where the cavity behind cannot be shown to drain and ventilate — a matter for a qualified professional
- Positions where open joints would give pests or debris an easy route into the cavity
Planning
Planning considerations
- An open joint only works because the control layer is elsewhere, so confirming where that layer sits is the first question for a qualified professional
- What is visible through the joint is part of the design, so the backing's colour and finish is chosen rather than inherited
- Cavity arrangements, barriers and materials are determined by qualified professionals and by the relevant authority
- A baffle within the joint can remove the direct path for wind-driven rain while leaving the joint open to air
Layout
Layout considerations
- Joint width is the elevation's finest line, and a small change in it alters the whole reading
- Horizontal and vertical joints do not have to be the same width, and often should not be
- The joint grid and the panel setting-out are one drawing, since a joint can only land where a panel edge does
- Where the joints meet an opening, a corner or the base, the grid either resolves or visibly does not
Materials & finishes
Materials and finishes to discuss
Named generically as starting points to discuss with professionals — not specifications, and not priced.
Consider:rainscreen panels or boardscladding support systems and railsbreather membrane behind the cavityjoint baffles or profilesdark-finished backing behind the jointcavity closures and trays
- The cavity behind an open-jointed facade is expected to be wet at times, which is normal provided it drains and dries
- Anything blocking the cavity turns the drained face above it into a shelf
- Backing materials visible through the joints are exposed to more light and weather than backing usually is
Maintenance & durability
Maintenance and durability questions
- Open joints let debris into the cavity, so how it is kept clear is worth settling early
- Panels are often demountable, which only helps if the fixings stay reachable and matching panels still exist
- The joints are the part most visible at close range, so they show soiling first
Professional review
What to ask a qualified professional
Bring these questions to a designer, contractor or the relevant qualified professional or authority.
- Which layer on this wall does the designer rely on to control water, and where is it in the section?
- How is the cavity drained and ventilated at the base, at the head and at every interruption?
- What would be visible through the joints, and how would that surface be finished?
- What joint width and baffle arrangement would suit this exposure?
- What provisions within the cavity are determined by the fire strategy on this building?
More ideas
Related ideas
Timber Cladding Facade →Cladding an elevation in natural timber boards for warmth and grain, and the weathering, movement and ventilation questions that come with a living material.Brick and Render Mix →Pairing a brick base or band with render above so two systems share one elevation, and the junction, weathering and movement questions where they meet.Charred Timber Facade →Cladding an elevation in charred timber for deep tone and texture, and the char-depth, rub-off and re-oiling questions that set it apart from plain timber.Composite Cladding →Choosing wood-polymer composite boards for a timber-like elevation with reduced upkeep, and the colour, expansion and fixing questions to weigh.Dark Exterior Scheme →Committing an elevation to a dark palette for a bold, recessive look, and the heat-gain, fade and contrast questions a dark facade raises.Fibre-Cement Cladding →Cladding an elevation in factory-finished fibre-cement boards for a timber-like line, and the cutting, fixing and dust questions to plan around.Gable Feature →Explore how cladding, applied timber or a feature window can turn a plain gable into a facade highlight, plus the questions to confirm first.Wheeled Track as Landform →Building a wheeled track as moulded ground rather than equipment on a flat pad, so it becomes the site's topography, screens and shelters what sits behind.
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