Short answer: Yes, acrylic is made for outdoor use: it is UV-stable through its full thickness, and Röhm (Plexiglas, Acrylite) and 3A Composites (Perspex) warrant clear sheet against yellowing for 30 years. The keys are leaving room for thermal expansion (a 48 in. panel moves about 0.2 in. over a 100 °F swing), drilling bolt holes at least twice the bolt diameter, and choosing a thickness for the wind load. Use polycarbonate where vandalism or heavy impacts are likely.
Key facts
- Warranties: 30 years against yellowing on clear Plexiglas, Acrylite, and Perspex sheet; 10 years on standard colors (Röhm, 3A Composites); 10-year limited warranty on Plaskolite Optix.
- Thermal expansion: 0.00004 in. per in. per °F (about 7 × 10-5 per °C). A 48 in. panel changes about 0.002 in. per °F, or about 0.20 in. over 100 °F (Acrylite).
- Dark tints in the sun (under 60% light transmission, facing south or southwest) move about 1.4 times as much as clear (Acrylite).
- Moisture: acrylic also grows slightly as it absorbs water, about 0.5% at 100% relative humidity (Acrylite). Perspex says to allow 5 mm per meter (about 1/16 in. per foot) in both directions for heat and humidity combined.
- Bolt holes: at least 2 times the bolt diameter, centered at least 1.5 hole diameters from the edge (Acrylite).
- Panels 4 × 4 ft or larger: install in frames, not with screws or bolts (Acrylite).
- Temperature range: Acrylite rates extruded sheet for −30 to 190 °F, with 160 °F as the continuous limit.
How long does acrylic last outside?
Decades, for quality sheet. Acrylic doesn't need a surface coating to resist sunlight: the UV stability is built into the whole thickness. Röhm guarantees that clear Plexiglas won't yellow for 30 years and says outdoor service lives of 30 years and longer are common on roofs, facades, and noise barriers. Acrylite publishes 10-year Arizona weathering data for its Soundstop XT sheet showing light transmission still at 92% and yellowness index under 3.0. Perspex's older design guide guaranteed that clear sheet would stay above 85% light transmission over 10 years outdoors.
What changes over time: the surface may lose a little gloss and pick up fine scratches from wind-blown grit, and colors slowly shift (makers guarantee standard colors for 10 years). It doesn't rot or rust. More on aging in does acrylic turn yellow.
How do you mount acrylic outdoors?
Most outdoor acrylic failures are cracks at screw holes or panels bowing in their frames, and nearly all come from ignoring expansion. Acrylite says its sheet expands and contracts 3 to 8 times as much as glass or metal. Use the thermal expansion calculator for your panel, or do the math: length × temperature swing × 0.00004. A 96 in. sheet over a 100 °F swing moves about 0.38 in.; for installation, the clearance at each side is half the total.
Screwed or bolted panels (signs, small panels)
- Drill holes at least twice the bolt diameter. A 1/4 in. bolt gets a 1/2 in. hole. Acrylite recommends a rubber grommet in the hole to help prevent cracking.
- Keep holes away from edges: hole center at least 1.5 times the hole diameter from the edge, and more is better.
- Don't overtighten. Snug the fastener with a washer (Perspex recommends cup washers and self-locking nuts) so the panel can slide.
Standoffs are a clean way to mount outdoor signs because the holes are generously sized and the panel floats off the wall. See how to mount acrylic to a wall.
Framed panels (windows, larger panels)
Cut the panel shorter than the frame opening so it has room to grow. Acrylite's clearances for colorless extruded sheet installed at 55 to 75 °F:
| Opening dimension | Cut sheet shorter by | Minimum rabbet (channel) depth, by long side |
|---|---|---|
| Up to 36 in. | 1/16 in. | 7/16 in. (24 in.), 5/8 in. (36 in.) |
| 36 to 65 in. | 1/8 in. | 3/4 in. (48 in.), 7/8 in. (60 in.) |
| 65 to 90 in. | 3/16 in. | 7/8 in. (72 in.), 1 in. (84 in.) |
| 90 to 117 in. | 1/4 in. | 1-1/8 in. (96 in.) |
Dark-tinted sheet needs more clearance. The channel has to be deep enough that the panel can't pull out when it shrinks on a cold, windy day. Seal with materials that stretch: Acrylite lists high-performance silicone, polyurethane, or polysulfide sealants, vulcanized butyl tape, or EPDM, Santoprene, or closed-cell neoprene gaskets, and says to use primerless systems and avoid ordinary hardening glazing compound. Some sealants and construction adhesives craze acrylic, so if in doubt, ask the sealant maker. Peel the protective film right after installation so the sun can't bake it on. More in acrylic thermal expansion.
How thick should outdoor acrylic be?
Wind usually decides it. Acrylite's glazing guide gives these thicknesses for vertical windows at a design wind load of about 30 to 40 lb/ft², which it equates to 100 to 120 mph winds:
| Window area | Acrylite recommended thickness |
|---|---|
| 1 to 5 sq. ft. | 1/8 in. (3 mm) |
| 6 to 15 sq. ft. | 3/16 in. (4.5 mm) |
| 15 to 32 sq. ft. | 1/4 in. (6 mm) |
| 32 to 50 sq. ft. | 3/8 in. (9.5 mm) |
These assume the window is framed on all four edges and isn't much wider than three-quarters of its length. Signs held only at a few points flex more than framed glazing: we'd suggest 1/8 to 3/16 in. for a small sign flat on a wall, 1/4 in. for a sign on standoffs up to about 24 × 36 in., and 3/8 in. or more for larger panels held only at their edges. For anything large, high up, or near people, check your local code or ask an engineer. More guidance in what thickness acrylic do I need.
When is polycarbonate better outdoors?
Acrylic is much tougher than glass: Röhm rates Plexiglas about 11 times more break-resistant, and Acrylite says 10 to 20 times more impact-resistant. Polycarbonate is far tougher again. Choose polycarbonate for:
- Vandal-prone places, like bus shelters, schools, and ground-floor windows.
- Machine guards and sports areas where things hit the panel.
- Hail-prone roofs, unless you use an impact-modified acrylic made for it. Acrylite backs its greenhouse multi-skin sheet with a 10-year hail warranty; ordinary flat sheet has no such rating. See acrylic greenhouse panels.
The tradeoff is that polycarbonate scratches more easily and yellows outdoors without a UV-protective layer. Acrylic stays clearer longer, so it's the better choice for signs, display windows, and anything where looks matter. Acrylic vs polycarbonate.
Do colored acrylic signs fade?
Colored acrylic is colored all the way through, so it lasts much longer than paint or printed vinyl. Röhm guarantees colored Plexiglas colorfast for 10 years, and Perspex guarantees standard colors for 10 years. Perspex also notes that a new panel next to one that's been outside for years will almost always look slightly different, so order replacements and additions together when color matching matters. Fluorescent colors are the least lightfast and many suppliers sell them for indoor use only, so for permanent outdoor signs we'd steer you toward standard colors.
How do you clean acrylic outdoors?
Hose off dust and grit first, then wash with mild soap and water and a soft cloth or sponge. Don't wipe a dusty sign dry, and skip ammonia cleaners, solvents, and pressure washers at close range. Full method in how to clean acrylic.
We cut outdoor panels to size, drill mounting holes with the clearance you need, and add standoffs. Get a price in the instant quote, or see business signs with standoffs.
Questions
Is acrylic waterproof?
Yes. Rain and snow don't harm it, and water absorption is low: Perspex says acrylic can take up as much as 2% water over long periods, which shows up as slight swelling rather than damage. Seal the gaps around a panel so water doesn't get behind it.
Can acrylic handle hot summer sun?
Yes, in normal use. Acrylite rates extruded sheet for 160 °F continuous and 190 °F intermittent service. Dark colors in full sun in hot climates can get close to that with a dark backing and no airflow, so leave ventilation behind dark panels.
Can extruded acrylic go outside?
Yes. Acrylite's 30-year non-yellowing warranty covers extruded Premium FF, and Acrylite's outdoor glazing guidance is written for extruded sheet. Cast is often preferred for thick panels and machined parts, but both weather well.
Does acrylic crack in freezing weather?
Not from cold alone: Acrylite rates its sheet down to −30 °F. Cold-weather cracks almost always start at tight screw holes as the panel shrinks. See acrylic in cold weather.
Is acrylic OK near the ocean?
Yes. Perspex lists sea-water resistance, and Acrylite says its Premium FF sheet withstands saltwater spray. Rinse salt off regularly so it doesn't build into a gritty film. For boats, see acrylic for boat and RV windows.
Sources
- Acrylite: Glazing Fabrication, Technical Information 1320-1C
- Acrylite: Drilling Acrylite acrylic sheet
- Röhm / Plexiglas: Long service life
- Perspex: Design Guide (expansion, fixing, weathering)
- Acrylite: Soundstop XT technical information (10-year Arizona weathering)
- Acrylite: Premium FF extruded sheet