Sheet Insulation
Insulation Sheet | K-FLEX ST, PU & Solar HT Sheets
Insulation sheet provides flexible, customizable thermal and acoustic insulation for irregular surfaces, large flat areas, tanks, vessels, and applications where pre-formed tube insulation isn't suitable. K-FLEX elastomeric ST, high-performance PU, and UV-protected Solar HT sheets offer superior thermal performance, moisture resistance, and ease of installation for HVAC, refrigeration, and industrial applications.
Why Use Insulation Sheet?
Versatility for Complex Shapes
Sheet insulation can be cut, shaped, and formed to fit irregular surfaces, tanks, vessels, ductwork, and custom applications where standard tube insulation won't work.
Large Surface Coverage
Ideal for insulating flat surfaces, walls, floors, ceilings, and large equipment where continuous coverage is required.
Custom Fabrication
Sheets can be fabricated into custom shapes, gaskets, seals, and specialised components for unique insulation requirements.
Acoustic Insulation
Closed-cell sheet insulation provides excellent sound dampening for mechanical equipment, plant rooms, and noise-sensitive environments.
Condensation Control
High water vapour resistance (μ ≥ 7,000 for elastomeric sheets) prevents condensation on cold surfaces, tanks, and vessels.
K-FLEX Sheet Insulation Products
K-FLEX ST Elastomeric Sheet
Premium closed-cell rubber sheet for HVAC, refrigeration, and industrial applications. Available in standard, self-adhesive, and aluminium-faced versions.
- Material: Nitrile rubber (NBR/PVC)
- Temperature Range: -40°C to +105°C
- Fire Rating: BL-s2,d0
- Thermal Conductivity: λ₄₀ = 0.036 W/m·K
- Water Vapour Resistance: μ ≥ 7,000
- Thickness Range: 3mm to 32mm
- Formats: Rolls (10m × 1m) or flat sheets (2m × 1m)
- Options: Standard, self-adhesive, or aluminium-faced (ST ALU)
- Best For: Tanks, vessels, ductwork, irregular surfaces, acoustic insulation, condensation control
K-FLEX PU Polyurethane Sheet
High-performance polyurethane foam sheet for demanding insulation applications requiring superior thermal efficiency.
- Material: Closed-cell polyurethane foam
- Temperature Range: -50°C to +110°C
- Fire Rating: BL-s2,d0
- Thermal Conductivity: λ₄₀ = 0.026 W/m·K (30% better than ST)
- Water Vapour Resistance: μ ~3,000
- Thickness Range: 10mm to 50mm
- Best For: High-performance insulation, space-constrained applications, superior thermal efficiency, industrial cold storage
K-FLEX SOLAR HT Sheet
UV-protected EPDM sheet for outdoor, solar thermal, and high-temperature applications.
- Material: UV-resistant EPDM rubber
- Temperature Range: -40°C to +150°C
- Fire Rating: BL-s2,d0
- Thermal Conductivity: λ₄₀ = 0.038 W/m·K
- UV Resistance: Designed for outdoor exposure
- Format: Rolls
- Best For: Solar thermal systems, outdoor installations, high-temperature applications, weather-exposed surfaces
Self-Adhesive & Aluminium-Faced Options
K-FLEX ST Sheet is available with factory-applied self-adhesive backing for faster installation on clean, smooth surfaces. K-FLEX ST ALU features aluminium foil facing for enhanced vapour barrier, weather protection, and professional finish.
Applications
Tanks & Vessels
Insulate hot water cylinders, expansion vessels, buffer tanks, and process vessels to reduce heat loss and prevent condensation. Use ST or PU sheet depending on performance requirements.
Ductwork Insulation
Wrap rectangular or irregular ductwork with ST sheet to maintain air temperature and prevent condensation in HVAC systems.
Acoustic Insulation
Line plant rooms, mechanical spaces, and equipment enclosures with ST sheet to reduce noise transmission from pumps, compressors, and HVAC equipment.
Cold Stores & Refrigeration
Insulate walls, ceilings, and doors in cold stores, walk-in freezers, and refrigerated spaces with PU sheet for maximum thermal efficiency in minimal thickness.
Industrial Equipment
Custom-fabricate insulation for process equipment, heat exchangers, valves, and irregular industrial components using ST or PU sheet.
Solar Thermal & Outdoor Applications
Use SOLAR HT sheet for outdoor pipework, solar thermal collectors, and weather-exposed installations requiring UV protection and high-temperature resistance.
Automotive & Marine
Thermal and acoustic insulation for vehicle interiors, engine compartments, and marine applications using ST sheet.
Installation Guide
Surface Preparation
- Ensure surface is clean, dry, and free from dust, grease, and loose material
- Remove any rust, flaking paint, or contaminants
- Allow wet surfaces to dry completely before installation
Cutting & Shaping
- Measure the area to be insulated and add 10-20mm for overlaps
- Use a sharp knife or scissors to cut sheet to size
- For curved surfaces, make relief cuts to allow sheet to conform
- Cut templates from cardboard for complex shapes before cutting insulation
Standard Sheet Installation (ST, PU, SOLAR HT)
- Apply K-FLEX 520 contact adhesive to both the insulation and the surface
- Allow adhesive to become touch-dry (5-10 minutes)
- Press insulation firmly onto surface, working from one edge to eliminate air bubbles
- Use a roller or hand pressure to ensure full contact
Self-Adhesive Sheet Installation
- Ensure surface is smooth, clean, and dry
- Peel back protective film from adhesive backing
- Position sheet carefully and press firmly into place
- Work from one edge to eliminate air bubbles
- Seal joints with vapour-barrier tape
Sealing Joints
- Butt joints together tightly with no gaps
- Apply adhesive to joint edges and press together
- Seal all joints with K-FLEX vapour-barrier tape
- Ensure continuous vapour barrier with no breaks or damage
Technical Specifications
K-FLEX ST Elastomeric Sheet
| Property | Value |
|---|---|
| Thermal Conductivity (λ₄₀) | 0.036 W/m·K |
| Water Vapour Resistance (μ) | ≥ 7,000 |
| Fire Rating | BL-s2,d0 (EN 13501-1) |
| Service Temperature | -40°C to +105°C |
| Density | ~65 kg/m³ |
| Available Thickness | 3mm, 6mm, 9mm, 13mm, 19mm, 25mm, 32mm |
| Formats | Rolls (10m × 1m), Flat sheets (2m × 1m) |
K-FLEX PU Polyurethane Sheet
| Property | Value |
|---|---|
| Thermal Conductivity (λ₄₀) | 0.026 W/m·K |
| Water Vapour Resistance (μ) | ~3,000 |
| Fire Rating | BL-s2,d0 (EN 13501-1) |
| Service Temperature | -50°C to +110°C |
| Available Thickness | 10mm, 20mm, 30mm, 40mm, 50mm |
K-FLEX SOLAR HT Sheet
| Property | Value |
|---|---|
| Thermal Conductivity (λ₄₀) | 0.038 W/m·K |
| Fire Rating | BL-s2,d0 (EN 13501-1) |
| Service Temperature | -40°C to +150°C |
| UV Resistance | Excellent (designed for outdoor use) |
| Format | Rolls |
Product Comparison
| Property | K-FLEX ST | K-FLEX PU | K-FLEX SOLAR HT |
|---|---|---|---|
| Thermal Conductivity | 0.036 W/m·K | 0.026 W/m·K (Best) | 0.038 W/m·K |
| Vapour Resistance | μ ≥ 7,000 (Best) | μ ~3,000 | Good |
| Max Temperature | +105°C | +110°C | +150°C (Best) |
| UV Resistance | Indoor only | Indoor only | Excellent (outdoor) |
| Fire Rating | BL-s2,d0 | BL-s2,d0 | BL-s2,d0 |
| Best For | General HVAC, condensation control | High-performance, space-constrained | Outdoor, solar thermal, high-temp |
Sheet vs Tube Insulation
| Application | Use Sheet | Use Tube |
|---|---|---|
| Pipes | Irregular or oversized pipes | Standard pipe diameters (6-168mm) |
| Tanks & Vessels | ✓ Ideal | Not suitable |
| Ductwork | ✓ Ideal | Not suitable |
| Flat Surfaces | ✓ Ideal | Not suitable |
| Custom Shapes | ✓ Ideal | Limited |
| Installation Speed | Slower (cutting & adhesive) | Faster (pre-formed) |
Frequently Asked Questions
What thickness of sheet insulation do I need?
It depends on the application. For condensation control on cold surfaces, 13-19mm is typical. For thermal insulation on tanks and vessels, 19-32mm. For high-performance applications, PU sheet achieves the same thermal performance in 30% less thickness.
Should I choose ST or PU sheet?
ST sheet offers excellent moisture resistance (μ ≥ 7,000) and is ideal for condensation control. PU sheet has superior thermal efficiency (λ = 0.026 vs 0.036) and is best for space-constrained applications or maximum energy savings.
Can I use sheet insulation on pipes?
Yes, but pre-formed tube insulation is faster and easier for standard pipe diameters. Use sheet for oversized pipes, irregular shapes, or where tube isn't available.
Is self-adhesive sheet easier to install?
Yes, on smooth, clean surfaces. Self-adhesive backing eliminates the need for contact adhesive, speeding up installation. However, traditional adhesive provides stronger bonds on rough or irregular surfaces.
When should I use SOLAR HT sheet instead of ST?
Use SOLAR HT for outdoor applications, solar thermal systems, or anywhere exposed to UV radiation and weather. It's UV-protected and rated to +150°C. ST sheet is for indoor use only.
What's the difference between ST ALU and standard ST sheet?
ST ALU has aluminium foil facing for enhanced vapour barrier, weather protection, and professional finish. It's ideal for external surfaces, exposed installations, and applications requiring a reflective surface.
Can sheet insulation be used for acoustic insulation?
Yes, ST sheet provides excellent sound dampening. Use 13-25mm thickness for mechanical equipment, plant rooms, and noise-sensitive environments.
What adhesive should I use?
Use K-FLEX 520 contact adhesive for ST, PU, and SOLAR HT sheets. For self-adhesive versions, no additional adhesive is required on smooth, clean surfaces.
Related Resources
- Elastomeric Pipe Insulation Guide
- Complete Pipe Insulation Guide
- K-FLEX Premium Product Range
- Technical Data Sheets & Installation Guides
- Knowledge Centre & FAQs
Need help selecting the right sheet insulation? Contact our technical team for expert guidance on thickness, material selection, and installation.