PVC and WPC Louvers, Indoors and Out

The same slat profile can be sold for indoor and outdoor use, but the material inside differs. Outdoor grades contain UV stabilisers and are formulated to cope with heat; indoor grades are not. An interior PVC slat fixed outside will fade, become brittle and bow under afternoon sun, often within a single year.

We specify outdoor grades for anything exposed to sun or rain, even under a partial roof. On a sea-facing elevation we often prefer coated aluminium, which handles UV and salt better than plastics and spans further between supports.

Plastics and composites expand noticeably as they heat up. A long WPC slat fixed tight at both ends on a west wall will bow by mid-afternoon. We leave end gaps, use slotted holes or clip systems that let the slat move, and keep supports close enough that slats do not sag between them.

Near the coast, fixings are the weak point. Plated screws rust, stain the slats and eventually fail. We use stainless steel or coated fixings throughout outdoor work, including the anchors into the wall.

Louvers are fixed to a sub-frame, usually aluminium or galvanised steel, which is anchored to the wall. Laterite is soft and varies from block to block, so anchors must suit it and be set at enough points to spread the load. On a facade, wind load on a large screen can be considerable.

The sub-frame also creates a gap behind the louvers. That gap lets air move and rain drain away, rather than water sitting against the wall. It should be open at the bottom so nothing collects there.

Spacing and angle decide how private a screen is. Close spacing hides more but cuts airflow and light. Angled slats block the view from one direction while staying open in another, so a balcony screen can block the neighbour's window while letting you see the garden.

We stand at the important viewpoints with you, the street, the neighbouring balcony, the seat inside, and set the spacing and angle to suit, rather than using a standard gap.

Remember that privacy reverses at night. With lamps on inside and darkness outside, a louvered screen that hides you by day can show a good deal of the room to the street. If a balcony or bedroom is overlooked, plan curtains or blinds on the window behind the screen as well.

Horizontal louvers angled downward shed some rain, but in a monsoon gale water still blows through. Vertical slats let rain through freely. Floors behind louvered screens need a fall to drain, and furniture there should be outdoor-rated.

Timber louvers outdoors should be oiled before the rains and inspected afterwards. WPC and aluminium only need a wash to remove salt and grime once the monsoon ends.

Where a louvered screen fronts a room rather than an open veranda, the window or door behind it remains the real weather line. We check that its sill and frame drain properly, because louvers slow the water down and can leave it pooling against the glass for longer than an open elevation would.

Inside the house, louvers do a gentler job. A slatted partition between a living and dining area, or beside an entrance, gives a sense of separation without closing the room off. Light from the window still reaches the far side, and the breeze from a ceiling fan still crosses the space, which a solid wall or a cabinet would stop.

The slats can run floor to ceiling, fixed top and bottom to concealed channels, or stop short at a counter or low wall. Spacing is usually closer than outdoors because the aim is visual rather than shading. A timber or timber-look finish warms a room of hard floors and white walls; a painted PVC slat in the wall colour gives texture without a new material.

Overhead, louvered ceilings hide beams, ducts and wiring and soften a tall room's echo slightly. PVC is light enough to fix overhead without heavy framing, and it does not mind the moisture that collects under a roof slab in the monsoon. Lights and fans are planned into the slat layout so no slat has to be cut awkwardly around a fitting.