What are the best greenhouse panels?

For most framed hobby greenhouses the best panel is 8mm clear twin-wall polycarbonate with an anti-condensate coating, such as Palram's ThermaGlas. Palram rates 8mm clear twin-wall at 80% light transmission and a U-value of 3.3 W/m2K (about R-1.7), and Greenhouse Megastore listed a single 4 x 8 ft ThermaGlas 8mm sheet at $55 on October 29, 2026 — less than the same store's 6mm sheet. For cold climates, step up to 16mm triple-wall; for wood-frame DIY builds, clear corrugated Suntuf at roughly $32-34 per 26-inch x 8-foot panel is the simplest option.

What thickness of polycarbonate is best for a greenhouse?

8mm twin-wall is the best all-round thickness. Palram's published figures show the light-versus-insulation trade-off is small between 4mm and 8mm (82% vs 80% light, U-value 3.8 vs 3.3 W/m2K), while 16mm triple-wall cuts heat loss by about 30% compared with 8mm (U-value 2.3) at a cost of 76% light. Choose 4mm only for curved hoop or gothic frames and slide-in kit replacements, and 16mm only if you heat through a cold winter.

Is twin-wall or corrugated polycarbonate better for a greenhouse?

Twin-wall is better for insulation, corrugated is better for light and simplicity. Single-layer clear corrugated Suntuf transmits 90% of light per Palram but has no trapped air layer, so it insulates far less than twin-wall. It screws straight onto wood purlins with Palram's closure strips, which makes it the easier choice for a DIY wood-frame greenhouse used from spring through fall. If you heat in winter, twin-wall or triple-wall pays for itself.

Which side of a polycarbonate panel faces out?

The UV-protected side faces the sun. On multiwall sheets that side is marked on the protective film; on Suntuf corrugated panels Palram says to install the label side facing up toward the sky. Installing a panel upside down leaves the unprotected face exposed, and Palram warns this will eventually discolor the panel.

Do you need to tape the ends of twin-wall polycarbonate?

Yes. Palram's SUNLITE installation guide calls for solid aluminum sealing tape across the top open ends of the flutes and vented filter tape across the bottom ends, so condensation can drain while dust and insects stay out. The flutes should run downhill, not sideways. On curved installs where both ends sit at the bottom, Palram says to use vented tape on both ends.

Are Lexan greenhouse panels the same as polycarbonate panels?

Yes — Lexan is a polycarbonate brand name that dates back to GE Plastics and is now used loosely for any clear polycarbonate sheet. Lexan Thermoclear is a multiwall sheet line in the same category as Palram's SUNLITE and ThermaGlas. What matters when you shop is the structure (twin-wall, triple-wall or corrugated), the thickness, a co-extruded UV layer, and the written warranty, not the brand name on the search term.

How long do polycarbonate greenhouse panels last?

Look at the warranty rather than marketing claims. Palram warrants SUNLITE and ThermaGlas multiwall for 10 years against losing more than 10% of light transmission, and its Suntuf corrugated carries a lifetime residential warranty that allows 8.5% light loss in the first 10 years. Both hail warranties cover stones only up to 1 inch in diameter — the same size at which the National Weather Service starts classifying hail as severe.

Can I replace broken glass greenhouse panes with polycarbonate?

Usually yes, if the glazing bars can grip the thicker sheet. Single glass panes are thin, so 4mm twin-wall polycarbonate is the usual swap for an aluminum hobby greenhouse, and kit glazing clips may not close on anything thicker. Measure the existing pane and the rebate depth before ordering, and buy a couple of spare clips. Tempered glass cannot be cut after it is made, so if you want to stay with glass you need panes ordered to exact size.

Best Greenhouse Panels 2026: Twin-Wall vs. Triple-Wall vs. Corrugated Polycarbonate, Ranked

Quick Answer: The best greenhouse panels for most hobby greenhouses in 2026 are 8mm clear twin-wall polycarbonate with an anti-condensate coating, such as Palram’s ThermaGlas. Palram rates 8mm clear twin-wall at 80% light transmission and a U-value of 3.3 W/m²K (about R-1.7), and on October 29, 2026 Greenhouse Megastore listed a single 4 x 8 ft ThermaGlas 8mm sheet at $55 — cheaper than its own 6mm sheet at $75. For cold climates, 16mm triple-wall cuts heat loss by about 30% compared with 8mm, and for wood-frame DIY builds clear Suntuf corrugated (90% light, about $32–34 per 26-inch x 8-foot panel) is the simplest panel to buy and install.

“Greenhouse panels” covers three different products that happen to share a search term: multiwall polycarbonate sheets (twin-wall and triple-wall), single-layer corrugated polycarbonate roofing, and replacement panes for kit greenhouses. They are not interchangeable. The right one depends on whether you are building a new frame, replacing panels in a kit, curving sheets over hoops, or trying to keep a heated greenhouse warm through January. We compared six panels using Palram’s own published spec tables, installation guides and warranty documents, plus live retailer prices checked on October 29, 2026.

Greenhouse panels by the numbers:

80% vs 76% — light transmission of Palram’s 8mm clear twin-wall versus its 16mm clear triple-wall, per Palram’s SUNLITE specification table. Thicker multiwall costs you a few points of light in exchange for insulation.
U-value 3.8 → 2.3 W/m²K — Palram’s heat-loss figures for 4mm twin-wall versus 16mm triple-wall. That is about 39% less heat flow per square foot (our arithmetic from Palram’s table); 8mm twin-wall sits in between at 3.3.
28 in vs 55 in — Palram’s minimum cold-bending radius for 4mm versus 8mm twin-wall. Bend a sheet tighter than its rated radius and, per Palram, it fails early and the warranty is void — which is why hoop and gothic-arch frames use thin sheet.
1 inch — the largest hailstone covered by Palram’s 10-year hail warranties on both Suntuf and SUNLITE. It is also the size at which the National Weather Service begins classifying hail as severe.
$1.72 per sq ft — Greenhouse Megastore’s October 29, 2026 single-sheet price for 4 x 8 ft ThermaGlas 8mm ($55), versus $2.34 for its 6mm sheet and $5.72 for 16mm triple-wall (our arithmetic from listed prices).

Best greenhouse panels compared

Panel	Best for	Structure	Light transmission	Insulation (U-value)	Warranty	Price checked Oct 29, 2026
ThermaGlas 8mm Clear Twin-Wall	Best overall	Twin-wall, anti-condensate	80%	3.3 W/m²K (R-1.7)	10-year limited	$55 per 4 x 8 ft sheet
ThermaGlas 16mm Clear Triple-Wall	Best for cold climates	Triple-wall	76%	2.3 W/m²K (R-2.5)	10-year limited	$183 per 4 x 8 ft sheet
6mm (0.24 in) twin-wall 2 x 4 ft packs	Best budget / small builds	Twin-wall, generic	About 80% (seller-claimed)	Not published by most sellers	Varies by seller	Roughly $4.50–7.50 per panel in 12–24 packs
ThermaGlas 4mm Clear Twin-Wall (Easy Ship)	Best for hoops and kit repairs	Twin-wall, anti-condensate	82%	3.8 W/m²K (R-1.5)	10-year limited	$14.45 per 2 x 4 ft panel
Suntuf Clear Corrugated	Best for wood-frame DIY	Single-layer corrugated, 0.032 in	90%	Single layer (lowest)	Lifetime residential + 10-year hail	$31.69–33.99 per 26 in x 8 ft
DynaGlas Clear Corrugated	Best corrugated for condensation	Single-layer corrugated, anti-condensate	Up to 90%	Single layer (lowest)	See Palram dealer terms	$53 per 49.5 in x 8 ft

Light transmission and U-values are Palram’s published figures for clear SUNLITE multiwall (Palram states ThermaGlas offers the same light transmission and insulation as SUNLITE) and for clear Suntuf. R-values are our conversion (R = 5.678 ÷ U). Prices are retailer snapshots from Greenhouse Megastore, VEVOR, Walmart and two True Value hardware stores; full-size sheets ship by motor freight with a crating fee, so compare delivered cost, not sheet price.

1. ThermaGlas 8mm Clear Twin-Wall — Best Overall

Palram ThermaGlas 8mm Clear Twin-Wall Polycarbonate

Best overall · $55 per 4 x 8 ft sheet (Greenhouse Megastore, Oct 29, 2026) · 4 ft and 6 ft widths

80% light transmission and U-value 3.3 W/m²K (about R-1.7) for clear 8mm twin-wall, per Palram's table.
Built-in condensation control on the underside, so droplets sheet off instead of dripping on seedlings.
Co-extruded UV layer; Greenhouse Megastore lists 99.5% UV protection and a 10-year limited warranty.
Rated minimum cold-bend radius of 55 inches — fine for flat walls and gentle arches, too stiff for tight hoops.
Also sold as 2 x 4 ft "Easy Ship" panels (5 for $55.16) that travel by ground parcel instead of freight.

Sponsored link — we may earn a fee if you sign up. No extra cost to you.

ThermaGlas is Palram’s greenhouse version of its SUNLITE multiwall sheet. Palram’s own product page says it has the same light transmission, rigidity, insulation and co-extruded UV protection as standard SUNLITE, plus a condensation-control treatment on the inside face. That coating is the reason to buy it over generic twin-wall: Palram explains that condensation droplets reflect sunlight away from the crop and drip onto plants, which encourages moisture-related disease. In a closed winter greenhouse, the inside of the roof is wet most mornings.

The pricing quirk is real and worth exploiting. On October 29, 2026, Greenhouse Megastore listed a single 48-inch x 8-foot ThermaGlas 8mm sheet at $55 and the 6mm version of the same size at $75. In 2 x 4 ft Easy Ship panels the gap was the same: five 8mm panels for $55.16 versus five 6mm panels for $75.00. Palram’s figures show 8mm is slightly better insulated (U-value 3.3 vs 3.5) with the same 80% light, so at those prices there is no reason to buy the thinner sheet. Prices move, so check both before you order.

The catch is shipping. Full 4 x 8 ft and 6 ft-wide sheets go by motor freight in a wooden crate, and the retailer adds a crating fee at checkout. If you only need to re-glaze a few kit panels, the 2-foot-wide Easy Ship sizes avoid that entirely. If you are glazing a whole frame, the per-square-foot savings of big sheets usually outweigh the freight. For how multiwall compares with glass on light and safety, see our polycarbonate vs glass greenhouse comparison.

2. ThermaGlas 16mm Clear Triple-Wall — Best for Cold Climates

Palram ThermaGlas / SUNLITE 16mm Clear Triple-Wall Polycarbonate

Best for cold climates · $183 per 4 x 8 ft sheet (Greenhouse Megastore, Oct 29, 2026)

U-value 2.3 W/m²K (about R-2.5) — about 30% less heat loss than 8mm twin-wall per Palram's figures.
76% light transmission for clear sheet, four points below 8mm twin-wall.
2.7 kg/m² (about 0.55 lb per sq ft), roughly 1.8 times the weight of 8mm twin-wall.
Needs glazing profiles and framing sized for 16mm — hobby-kit channels are usually made for much thinner sheet.
10-year limited warranty on light transmission and hail up to 1 inch.

Triple-wall only makes sense if you pay to heat. Palram’s table puts 16mm clear triple-wall at a U-value of 2.3 W/m²K against 3.3 for 8mm twin-wall, so every square foot of glazing loses about 30% less heat — and in a small greenhouse, glazing is almost the entire envelope. If you run a heater from November to March, that is a real reduction in the heater’s runtime. If your greenhouse is unheated and used for season extension, the money is better spent elsewhere.

What you give up is light and cost. Clear triple-wall transmits 76% of light versus 80% for 8mm twin-wall, which matters most in the short, dim days when you need the heat savings. At Greenhouse Megastore’s October 29 prices, a 4 x 8 ft 16mm sheet ($183) cost about 3.3 times as much as an 8mm sheet ($55). A middle option is 8mm triple-wall: Palram lists it at a U-value of 3.0 with 76% light, and Greenhouse Megastore sold a 72-inch x 8-foot sheet at $159 (about $3.31 per square foot). Our guide on how to heat a greenhouse in winter covers heater sizing once you know your glazing’s heat loss.

3. 6mm Twin-Wall 2 x 4 ft Panel Packs — Best Budget

Generic 6mm (0.24 in) Twin-Wall Polycarbonate Greenhouse Panels, 2 x 4 ft

Best budget · roughly $4.50–7.50 per 2 x 4 ft panel in 12–24 packs · ships by parcel

Sold on Amazon, Walmart and VEVOR by brands such as DGSL, UMIG and VEVOR, in 6- to 24-panel packs.
Listings typically claim about 80% light transmission and a -40°F to 248°F (-40°C to 120°C) working range — seller claims, not independent tests.
Some packs include aluminum H-connectors and W-clips for simple wood or tube frames.
Check the listing for a co-extruded UV side; without it, clear polycarbonate yellows outdoors.
Warranty terms vary by seller and are rarely stated as clearly as Palram's.

For small builds — a cold frame, a lean-to, a 6 x 8 frame you are glazing yourself — the generic 2 x 4 ft packs are the cheapest way into twin-wall. VEVOR’s own store listed a 12-pack of 0.24-inch panels at $89.90 and a 24-pack of 0.16-inch panels at $107.90 in late October 2026, and Walmart sellers offered 14-packs of 0.16-inch panels for about $68. That works out to roughly $0.55–0.95 per square foot, well under the branded sheets above.

The trade is documentation. Palram publishes a light-transmission figure, U-value, bend radius and a written 10-year warranty for every thickness; most generic listings give a light figure and little else, and a few claim 90% light for twin-wall, which is above what Palram rates even its thinnest clear multiwall. Treat these panels as good-value glazing for structures you can easily re-panel later, and buy one pack more than you need, because matching the exact profile and tint a year later is unlikely. If your build is a covered tunnel rather than a rigid frame, our greenhouse frame kit guide covers hoops designed to take polycarbonate.

4. ThermaGlas 4mm Clear Twin-Wall — Best for Hoops & Kit Repairs

Palram ThermaGlas 4mm Clear Twin-Wall (Easy Ship 2 x 4 ft)

Best for curved frames and kit replacement panels · $14.45 per panel or $72.25 for 5 (Oct 29, 2026)

82% light transmission — the highest of Palram's clear twin-wall thicknesses.
Minimum cold-bend radius of 28 inches, half the 55 inches 8mm needs.
U-value 3.8 W/m²K (about R-1.5), the lowest insulation of the multiwall options here.
Anti-condensate underside and a 10-year limited warranty, per Greenhouse Megastore's listing.
Ships by ground parcel in 2 x 4 ft and 2 x 6 ft sizes, no crate.

Four-millimeter twin-wall is the right panel for two jobs where thicker sheet fails. The first is curving: Palram’s SUNLITE guide lists a minimum cold-bending radius of 700 mm (about 28 inches) for 4mm twin-wall, 1,050 mm for 6mm and 1,400 mm (about 55 inches) for 8mm. A backyard hoop or gothic frame with a tight crown needs the thin sheet, and the flutes must run along the curve, not across it. See our gothic arch greenhouse roundup for frames that ship ready for rigid glazing.

The second is kit repair. Many aluminum hobby greenhouses use thin twin-wall or single panes held in slide-in channels or spring clips, and a thicker replacement simply will not fit. Measure the old panel’s thickness and the channel width before ordering, and keep the broken panel as a template. For a temporary fix while the replacement ships, our greenhouse repair tape picks hold a cracked panel through a storm. If your kit uses a fabric or film cover instead of rigid panels, you need a different product entirely — see our greenhouse cover replacement guide.

5. Suntuf Clear Corrugated — Best for Wood-Frame DIY

Palram Suntuf Clear Corrugated Polycarbonate Panel

Best for wood-frame DIY · $31.69–33.99 per 26 in x 8 ft (True Value dealers, Oct 2026) · also 10 ft and 12 ft

90% light transmission for clear 0.032-inch sheet, measured to ASTM D1003, per Palram.
Sold at Home Depot and hardware stores in 26-inch widths; 49.6-inch widths through dealers.
Lifetime residential warranty (8.5% light loss allowed over 10 years) plus 10-year hail warranty up to 1 inch.
Palram's install guide: purlins no more than 36 in apart (24 in recommended), minimum roof pitch 1-1/2 in 12.
Single layer, so it insulates far less than any twin-wall — best for spring-to-fall growing.

Corrugated polycarbonate is what most people picture when they build a wooden greenhouse from a plan: panels screwed to horizontal purlins over a 2x4 frame, with foam closure strips filling the wave at the top and bottom. Palram even publishes its own 8 x 10 ft, 3/12-pitch garden greenhouse plan using sixteen 26-inch x 8-foot and five 26-inch x 12-foot clear Suntuf panels, 2-inch WoodTite fasteners and 36-inch foam closures. At the hardware-store prices above, the sixteen 8-foot panels alone come to roughly $507–544.

Three details from Palram’s installation guide decide whether a Suntuf roof lasts. Install the label side facing the sky so the UV layer faces the sun. Pre-drill every fastener hole with a 1/4-inch bit for Palram’s own fasteners, because the sheet moves with temperature and undersized holes cause buckling. And use Palram’s EPDM-washered screws — the guide states that incompatible washers can cause panel failure that the warranty does not cover. Lowe’s sells a near-identical alternative, Tuftex PolyCarb; Lowe’s own product documentation lists Palram Americas of Kutztown, Pennsylvania as its manufacturer.

6. DynaGlas Clear Corrugated — Best Corrugated for Condensation

Palram DynaGlas Clear Corrugated Polycarbonate Panel

Best corrugated for humid greenhouses · $53 per 49.5 in x 8 ft (Greenhouse Megastore, Oct 29, 2026)

Co-extruded UV layer on top plus an anti-condensation treatment on the underside, per Palram.
Palram's own Suntuf guide recommends DynaGlas over standard Suntuf where greenhouse drip is a concern.
Wide 49.5-inch sheet covers about 33 sq ft — roughly $1.61 per sq ft at the listed price.
Same single-layer insulation limits as Suntuf; still needs slope and a way to collect condensate.
Sold through greenhouse dealers rather than big-box stores.

Here is the detail most Suntuf buyers never read: Palram’s own installation guide has a “Greenhouse Applications” section warning that condensation formation and dripping is common in enclosed, humid structures like greenhouses, and that if dripping is a concern you should use Palram’s DynaGlas instead. DynaGlas carries an anti-condensate coating that promotes the flow of condensation along the inside of the panel, so droplets are minimized and more light gets through.

The coating does not make water disappear. Palram notes that without proper slope and some way to collect and remove condensate, dripping will still occur at purlins and other supports. In practice that means a steeper roof than the 1-1/2-in-12 minimum and a gutter or drip line along the eaves. At $53 for a 49.5-inch x 8-foot sheet, DynaGlas was also cheaper per square foot than big-box Suntuf in our October snapshot, though freight from a greenhouse dealer can erase that advantage on small orders.

Panel thickness compared: light, insulation, bend radius and cost

Clear multiwall	Light transmission	U-value (W/m²K)	Approx. R-value	Weight (kg/m²)	Min. bend radius	Greenhouse Megastore price per sq ft
4mm twin-wall	82%	3.8	R-1.5	0.8	28 in	$1.81 (2 x 4 ft)
6mm twin-wall	80%	3.5	R-1.6	1.3	41 in	$2.34 (4 x 8 ft)
8mm twin-wall	80%	3.3	R-1.7	1.5	55 in	$1.72 (4 x 8 ft)
10mm twin-wall	79%	2.9	R-2.0	1.7	69 in	$3.41 (4 x 8 ft)
8mm triple-wall	76%	3.0	R-1.9	1.7	Not listed	$3.31 (6 x 8 ft)
16mm triple-wall	76%	2.3	R-2.5	2.7	Not listed	$5.72 (4 x 8 ft)

Light, U-value, weight and bend radius come from Palram’s SUNLITE product page and SUNLITE Technical & Installation Guide; R-values are our conversion; price per square foot is our arithmetic from single-sheet prices on October 29, 2026. The table shows why 8mm twin-wall is the default: it gives up two points of light against 4mm, insulates about 13% better, and at current prices costs less per square foot than either neighbor.

How to install twin-wall panels so they last

Most early panel failures are installation failures. These come straight from Palram’s SUNLITE Technical & Installation Guide:

Run the flutes downhill. Palram says rib channels should slope downward so condensation drains by gravity and dirt does not collect inside. On a roof, Palram treats a 5% slope as the minimum and 10% or more as preferable.
Tape the ends correctly. Solid aluminum tape seals the top open ends; vented filter tape goes on the bottom ends so moisture can escape. Sealing both ends solid traps water in the flutes, where it fogs the panel and grows algae. Greenhouse Megastore sold 1-inch x 150-foot top-sealing aluminum tape for $14.99 and a 108-foot roll of vent tape for $40.45.
Leave room to move. Palram says SUNLITE expands about 1/8 inch per 3-1/3 feet of length over a 90°F temperature range, and recommends doubling that allowance. On an 8-foot sheet that is a little over half an inch of total clearance, split between both ends.
Oversize the screw holes. Pre-drill each hole 3/16 inch (5 mm) larger than the screw, use sealing washers, and stop tightening before the washer distorts. Palram recommends installing at 50–77°F to keep expansion small.
Peel the top film right away. Palram warns that the exterior protective film left in direct sun can fuse to the sheet, becoming very hard to remove and voiding the warranty.

Rigid panels need rigid fixing. In windy sites, pair them with properly rated fasteners and clips — our greenhouse clips guide explains why cheap plastic snap clips fail first.

What the warranties actually cover

Palram is one of the few panel makers that publishes full warranty documents, and they are worth reading before you buy:

SUNLITE and ThermaGlas multiwall: 10 years against losing more than 10% of light transmission (ASTM D1003) and against yellowing beyond set limits, plus a 10-year hail-breakage warranty. Refunds are pro-rated — 100% through year 3, falling to 5% by the end of year 10.
Suntuf corrugated: a lifetime residential warranty allowing up to 8.5% light loss in the first 10 years and 1% per year after that, plus 10-year hail coverage. It applies only on a personal residence, only for the owner at the time of installation, and it is non-transferable — the warranty ends when the property changes hands.
Both hail warranties cover hailstones up to 1 inch in diameter traveling up to 20 meters per second (about 45 mph). The National Weather Service classifies hail of 1 inch or larger as severe, so the storms most likely to break a panel are outside the coverage. If you garden in hail country, read our Colorado greenhouse guide on why panel thickness and framing matter more than the warranty.

One shopping trap sits on the same shelf: Palram’s PVC corrugated line, Palruf, looks almost identical to Suntuf polycarbonate. Palram’s own FAQ gives PVC Palruf a maximum service temperature of 122°F versus 212°F for polycarbonate Suntuf. For a structure designed to trap heat, buy the polycarbonate.

How to choose greenhouse panels

Start with the frame. A kit with glazing channels dictates the thickness; measure the old panel and the channel before you shop. A wood frame with purlins suits corrugated; an aluminum or steel glazing-bar frame suits multiwall.
Decide whether you heat. Unheated season-extension greenhouses do well with corrugated or 4–8mm twin-wall. Heated winter greenhouses justify 8mm triple-wall or 16mm triple-wall.
Check the curve. For hoops and arches, compare the frame’s radius with Palram’s minimum bend radius — 28 inches for 4mm, 55 inches for 8mm.
Pay for anti-condensate in closed greenhouses. ThermaGlas and DynaGlas cost little or nothing extra at current prices and keep drip off plants.
Price per delivered square foot. Freight and crating fees change the math on big sheets; 2-foot-wide parcel-shipped panels cost more per square foot but nothing to deliver.
Buy the accessories with the panels. Aluminum top tape, vent tape, U or H profiles and washered screws are part of the system, not optional extras.

If you are still deciding between building and buying, our best greenhouse kits roundup covers kits that ship with polycarbonate already cut to size, and our greenhouse plastic guide covers film for hoop houses where rigid panels are overkill.

The bottom line

Buy ThermaGlas 8mm clear twin-wall for a framed greenhouse — at October 2026 prices it is cheaper per square foot than 6mm, insulates better, and its anti-condensate underside keeps drip off your plants. Step up to 16mm triple-wall only if you heat through winter and your frame can take it. Use 4mm twin-wall for tight hoops and kit repairs, generic 6mm packs for small builds on a budget, and Suntuf or DynaGlas corrugated for a wood-frame greenhouse you use from spring through fall. Whatever you choose, run the flutes downhill, tape both ends with the right tape, and oversize every screw hole.