Sealants for Food Processing & Cold Storage Facilities
NSF compliance, temperature requirements, and material selection for food processing facilities
Last updated: November 8, 2025
Quick Reference
Most common applications and what works:
Walk-in freezers & cooler panels
Use silicone sealant. Stays flexible to -60°F, handles the temperature swings when doors open and close.
Processing equipment seals
Need NSF-51 certified sealant for direct food contact. Check your HACCP plan.
Floor joints in production areas
Polyurethane sealant works best. Can handle forklift traffic and takes a paint or epoxy topcoat.
Wash-down zones (walls, ceilings)
Mold-resistant silicone sealant. Chemical resistant to facility cleaners.
Ovens, steam lines, hot areas
High-temp silicone sealant rated for your specific temperature. Most handle 400°F+.
NSF Certifications
If you're working in food processing, NSF certification matters. Here's what the different ratings mean:
NSF-51 Certified
Direct food contact zones. Tested for non-toxicity and won't leach chemicals into food. Required in areas where sealant might touch food or food contact surfaces.
Common locations: Processing equipment seals, conveyor systems, food prep surfaces
NSF-Listed (Non-Food Contact)
Splash zones and indirect contact areas. Tested for food facility use but not meant for direct food contact. Covers most of your facility.
Common locations: Walls, floors, drains, HVAC penetrations, walk-in coolers
Most facilities need both. Use NSF-51 where required by code or your HACCP plan, and NSF-Listed everywhere else in the processing environment.
Silicone vs Polyurethane
Both work in food facilities, but they're good at different things.
| Silicone | Polyurethane | |
|---|---|---|
| Temperature range | -60°F to 400°F+ | -40°F to 200°F |
| Movement capability | ±50% (excellent) | ±25% (good) |
| Chemical resistance | Very good | Excellent |
| Paintable | No | Yes |
| Best for | Freezers, ovens, temp swings | Floor joints, high-traffic |
Rule of thumb: Use silicone where temperature varies a lot. Use polyurethane for floors and areas that need paint or epoxy topcoat.
Cold Storage
Walk-in coolers and freezers fail for two reasons: wrong sealant or no backer rod.
What happens in freezers
- Thermal cycling: Joints expand and contract with every freeze-thaw cycle
- Moisture infiltration: Warm humid air meets cold surfaces, condensation gets in cracks
- Ice expansion: Any water in the joint freezes and pushes the sealant out
Requirements
- Stays flexible below -40°F (silicone is your best bet)
- High movement capability (±50% minimum for freeze-thaw)
- NSF-Listed for food facility use
- Proper joint design with backer rod (prevents three-sided adhesion)
What to use
For freezer panels and walk-in coolers: NSF-Listed silicone sealant. Look for products rated to at least -40°F with ±50% movement capability.
For floor joints: If you're sealing expansion joints in a freezer floor, polyurethane sealant can work IF the temp stays above -20°F and you need paintability. Below that, stick with silicone sealant.
Don't forget backer rod: Get closed-cell foam backer rod that's about 25% larger than your joint width. This is critical in cold storage to prevent three-sided adhesion.
See the main Sealant Guide - Silicone Section for more details on cold-temperature applications
High Temperature
Ovens, smokers, steam cleaning areas, and anywhere above 200°F.
Temperature ratings matter
- 200°F-350°F: Standard high-temp silicone works
- 350°F-500°F: Need RTV silicone rated for continuous high heat
- 500°F+: Specialized ceramic-filled or high-temp RTV
Don't use polyurethane above 200°F. It'll break down. Silicone or high-temperature specialty sealants only.
What to use
For most ovens and smokers (300°F-400°F): Red high-temp silicone sealant. The red color is standard for high-heat applications and makes it easy to identify during inspections.
For steam lines or intermittent spikes above 400°F: Look for RTV silicone sealant specifically rated for continuous high heat. Check the product spec sheet for the exact temperature rating.
Common mistake: Using "high-temp" caulk from the hardware store that's only rated to 250°F. Always check the continuous operating temperature, not just the peak.
See the main Sealant Guide - High-Temp Section for detailed temperature ratings
Sanitary Wash-Down
Areas that get hosed down daily with hot water, sanitizers, and pressure washers.
What fails in wash-down zones
- Poor surface prep (water gets behind the sealant)
- Wrong sealant type (some break down with chlorine or quaternary ammonia cleaners)
- Mold growth (water trapped in poorly designed joints)
Requirements
- Mold and mildew resistant (most silicones have this)
- Chemical resistance to facility cleaning agents
- NSF-Listed minimum, NSF-51 if near food zones
- Smooth finish (no texture for bacteria to hide in)
What to use
For walls and ceilings in wash-down areas: Mold-resistant silicone sealant with chemical resistance. Most kitchen/bath silicone sealants have mildewcide, but verify it can handle your facility's specific cleaners.
For cove base and floor-to-wall joints: If you're in a high-traffic zone that gets painted or sealed with epoxy, use polyurethane sealant. Otherwise, silicone sealant gives better long-term mold resistance.
Testing tip: If you're switching cleaning products, test your sealant with a sample first. Some quaternary ammonia cleaners can degrade certain silicone sealants over time.
See the main Sealant Guide - Silicone Section for mold-resistant options
Compliance Checklist
Before you seal, check these requirements:
- NSF certification matches your zone (NSF-51 for food contact, NSF-Listed for splash zones)
- Temperature rating covers your min and max operating temps
- Chemical compatibility with your cleaning protocols
- Movement capability matches joint design (Class 25 minimum, Class 50 for thermal cycling)
- Surface prep is clean and dry (primer if needed)
- Backer rod sized correctly (25% larger than joint width)
- HACCP plan reviewed (if applicable to your facility)
Most inspection failures come from using the wrong NSF rating or skipping surface prep. Get these two right and you're ahead of 80% of problems.
Related Resources
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