Types Of Covering Materials Best For Alaska Greenhouses

Alaska presents a unique set of challenges and opportunities for greenhouse growers. Long, dark winters with subzero temperatures, heavy snow loads, high winds, and short but intense growing seasons mean that the choice of greenhouse covering material is one of the most important decisions a grower can make. The right covering balances light transmission, insulation, strength, snow-shedding ability, and cost. This article examines the best covering materials for Alaskan greenhouses, compares performance metrics, and provides practical recommendations for different locations and scales of operation.

Climate and structural considerations unique to Alaska

Alaska’s climate is not uniform. Interior regions can experience extremely cold, dry winters with low humidity and deep snow, while coastal areas and the southeast can be milder and wetter with higher wind and salt exposure. Any greenhouse covering in Alaska needs to address four primary concerns:

• Insulation and thermal retention to reduce heating load during long, cold nights.
• Light transmission and diffusion to make the most of low-angle winter sun and long twilight periods.
• Structural strength and snow-shedding to withstand snow loads and ice buildup.
• Durability against UV radiation, wind abrasion, and freeze-thaw cycles.

Selecting a covering requires weighing these factors against budget and the intended use of the greenhouse (season extension, year-round production, seed starting, or specialty crops).

Key performance factors to evaluate

When comparing coverings, use these concrete performance measures:

• Light transmission: percentage of photosynthetically active radiation (PAR) that passes through.
• R-value or U-value: thermal resistance or conductance, indicating insulation performance.
• Service life: expected years before replacement under Alaskan conditions.
• Impact resistance and structural load rating: wind and snow load capacity when mounted on proper framing.
• Cost per square foot installed and life-cycle cost (materials + heating savings + replacement).

Understanding these metrics helps match materials to local conditions and production goals.

Rigid polycarbonate (twin-wall and triple-wall)

Overview and why it works well in Alaska

Multiwall polycarbonate is a leading choice for Alaskan greenhouses because it balances high light transmission with superior insulating value and good impact resistance. Typical twin-wall panels transmit 70-80% of light and provide R-values in the 1.5 to 2.0 range, while triple-wall versions push the R-value to around 2.0-3.0 depending on thickness and cell structure.

Strengths

• Good insulation relative to single-layer film.
• Lightweight and impact resistant; withstands hail and minor impacts without shattering.
• Diffuses light, reducing hotspots and providing more even canopy illumination.
• Reasonable service life: 10-15 years with UV-stabilized grades, sometimes longer with careful maintenance.

Weaknesses and installation notes

• Cost is higher than polyethylene film; typical material cost is $2.00-$5.00 per square foot (varies with thickness and brand), and installation requires compatible framing and edge sealing.
• Snow and ice can accumulate on shallow pitches; ensure roof pitch of at least 30 degrees for effective snow-shedding in heavy-snow zones, or use heated wires/roof heaters in critical areas.
• Edge sealing and condensation management are essential. Install proper end caps, vent holes for drainage, and ridge ventilation to prevent water buildup inside the cells.

Best use cases

• Year-round small-to-medium hobby and commercial greenhouses in interior and coastal Alaska where improved insulation dramatically reduces heating costs.

Greenhouse polyethylene film (single and double layer with inflation)

Overview and why it is popular

Polyethylene (PE) greenhouse film is widely used for its low cost and ease of installation. Single-layer film transmits 80-90% of light but offers little insulation. Double-layer inflated systems (air-inflated “polytunnel” with a layer of air between two films) significantly increase R-value and reduce heat loss.

Strengths

• Lowest upfront material cost: film can run $0.10-$0.50 per square foot depending on quality and thickness.
• Flexible for retrofit projects and temporary structures; inexpensive to replace after damage.
• Double-layer inflated systems improve thermal performance and reduce frost risk when properly sealed and continuously inflated.

Weaknesses and practical caveats

• Service life is limited in Alaska unless using heavy-duty UV-stabilized film: typical life is 3-6 years for commercial films, sometimes less under wind and abrasion.
• Single-layer offers little thermal protection; double-inflated systems require a blower and reliable power to maintain inflation.
• Film is vulnerable to puncture and wind flapping; framing and edge fastening must be robust to prevent tears.

Best use cases

• Low-cost season extension tunnels and high tunnels for summer crops.
• Temporary or mobile greenhouses, seed-starting houses, or entry-level operations where capital is constrained.

Tempered glass (single and double glazed)

Overview and key attributes

Glass is the traditional greenhouse covering. It offers excellent light transmission (up to 90% for high-quality glass) and a long service life. Double-glazed glass units improve thermal performance versus single panes.

Strengths

• Premium light transmission and clarity, ideal for maximum solar gain on bright days.
• Long lifespan–decades if properly maintained–and minimal UV degradation.
• Aesthetically pleasing and commonly used for conservatories or high-value crops where light quality is critical.

Weaknesses and critical limitations in Alaska

• Poor insulating value for single-pane installations; double-glazing improves R-value but at substantial cost and structural burden.
• Heavy weight requires very strong framing and foundations to resist snow loads and wind. Glass can break from hail or collision, which is a serious risk where storms and freeze-thaw cycles are common.
• Cost is high: installed glass can easily be $8-$15+ per square foot or more depending on glazing type and framing.

Best use cases

• South-facing, well-engineered structures in milder Alaskan zones or for specialty operations where maximum light quality outweighs heating costs.
• Use in combination with internal thermal curtains to limit night heat loss.

Acrylic and rigid fiberglass reinforced panels

Overview

Acrylic sheets and fiberglass reinforced panels (FRP) are mid-range options. Acrylic has high light transmission comparable to glass but is lighter; FRP is durable and diffuse light but can yellow over time.

Strengths

• Acrylic offers clarity, reasonable impact strength, and lower weight than glass.
• Fiberglass reinforced panels diffuse light well and withstand impacts, with lower cost than polycarbonate or glass.

Weaknesses

• Fiberglass panels tend to discolor and reduce light transmission over years, especially under high UV exposure.
• Acrylic can be scratched and may become brittle under extreme cold; both require careful installation and maintenance.

Best use cases

• Small structures or lean-tos where a transparent, durable sheet is desired but budget or weight limits preclude glass.

Supplemental and insulating options (thermal curtains, bubble wrap, row covers)

Internal thermal curtains and insulation

Adding a retractable thermal curtain (insulating blanket) inside the greenhouse is one of the most effective ways to reduce heat loss during long Alaskan nights. Thermal curtains can reduce heat loss by 30-50% when deployed and are cost-effective compared to replacing the entire shell.

Bubble wrap and insulating films

Low-cost bubble-wrap insulation applied to internal framing can add R-value quickly; it can be replaced each season and is particularly effective in small hobby greenhouses.

Floating row covers and cloches

Inside the greenhouse, light-weight floating row covers extend plant-level temperatures and protect seedlings on the coldest nights without significantly reducing light.

Practical selection guide and recommendations

• For year-round production in Interior Alaska: prioritize insulation. Twin- or triple-wall polycarbonate combined with internal thermal curtains is the best balance of durability, light diffusion, and reduced heating cost.
• For coastal and milder regions: twin-wall polycarbonate or heavy-duty double-layer polyethylene is cost-effective. Provide robust anchoring and corrosion-resistant fittings for salt exposure.
• For short-season or seasonal summer production: single-layer polyethylene film over a sturdy hoop frame is economical and allows rapid turnarounds; plan on replacing film every 3-4 years.
• For hobbyists and small-scale growers: consider rigid polycarbonate for greenhouses that must last with minimal maintenance; add bubble-wrap insulation for winter.
• For high-value specialty crops where maximum light is essential: glass with double glazing and thermal curtains can be justified if the structure is engineered to handle snow and wind loads.

Installation and maintenance tips specific to Alaskan conditions

• Roof pitch and snow management: design roof slopes >= 30 degrees where heavy snow is expected; consider heated roof elements or manual snow removal plans for gentler slopes.
• Frame strength: use steel or heavy-duty aluminum framing sized to local snow and wind load specifications. Factor in drift loads where snow accumulates.
• Edge sealing and condensation control: polycarbonate cells must be capped and vented; inflatable double-layer films need continuous monitoring of blower systems and leak detection.
• UV and abrasion protection: choose UV-stabilized films and panels. Install windbreaks and proper edge clamping to minimize flapping abrasion.
• Maintenance schedule: inspect for punctures and seal them quickly; clean glazing annually with mild soap and soft cloth; replace films proactively before winter if they are brittle or heavily stained.

Cost considerations and lifecycle ROI

When choosing a covering, calculate lifecycle costs not just initial material expense. Consider:

• Heating energy savings from higher R-value materials.
• Replacement frequency and disposal costs.
• Crop yield impacts from light transmission and diffusion.
• Labor costs for cleaning, snow removal, and maintenance.

A more expensive-but-insulating covering often pays back through lower heating needs in year-round operations. Conversely, for seasonal tunnels, low initial cost may be optimal.

Final practical takeaways

• For most Alaskan growers who want year-round production with manageable heating costs, twin-wall or triple-wall polycarbonate with a tight frame and internal thermal curtains is the best overall solution.
• Double-layer inflated polyethylene is the lowest-cost insulating option for larger seasonal greenhouses if a reliable blower and backup power are available.
• Glass should be reserved for specialized applications where light quality outweighs heating penalties and structural costs.
• Always design the structure for local snow and wind loads, prioritize proper sealing and condensation control, and plan for routine maintenance and timely replacement of vulnerable materials.

Choosing the right covering material for Alaska is a balance of light, heat, strength, and budget. Matched to local conditions and supported by good framing and insulation practices, the right choice will allow successful, productive greenhouse growing even in Alaska’s demanding climates.