Wall thickness is an important consideration when building with insulated metal panels (IMPs). IMP walls provide many benefits – they are durable, energy efficient, and quick to install. But determining the right thickness for your project requires looking at several factors.
What are IMPs?
IMPs, or insulated metal panels, are prefabricated building panels made of two metal skins surrounding an insulating foam core. The metal skins are most often steel or aluminum, while the core is typically polyurethane or polyisocyanurate foam.
IMPs provide a continuous layer of insulation and an air tight building envelope. They are available in a range of thicknesses, with thicker panels providing greater insulation value. Common thicknesses range from 2 inches up to 6 inches.
Benefits of IMP walls
There are several benefits that make IMP walls a popular building material:
- Thermal performance – The insulated core provides excellent insulation for energy efficiency. Thicker panels improve insulation values.
- Strength – The metal skins give IMP walls strength and rigidity.
- Weather resistance – IMPs are designed for exterior use and protect against wind, rain, and moisture.
- Speed of installation – IMPs install quickly compared to other wall systems.
- Design options – IMPs are available in a range of colors, textures, and reveal profiles.
IMP wall thickness considerations
Choosing the right thickness IMP wall involves looking at several factors:
Climate and location
The climate where the building is located will impact the insulation needs. In colder regions with more extreme weather, thicker panels may be recommended. In temperate climates, thinner panels may suffice.
Building use
The building’s use and interior temperature requirements will also affect insulation needs. For example, a commercial freezer building would need thicker insulation than a typical office building.
Energy codes
Local building energy codes provide minimum insulation R-values for walls. The IMP thickness must meet or exceed the code requirements.
Budget
Thicker IMPs improve insulation but also increase material costs. The budget for the project is a factor in choosing appropriate thicknesses.
Design loads
The expected wind, snow, seismic, and other loads impact the necessary strength and thickness of the IMP walls.
Fire resistance rating
Some buildings require walls to have a fire resistance rating (FRR). Thicker IMPs generally provide higher FRR.
Spans
For long spans between structural supports, thicker panels may be needed to provide sufficient stiffness and strength.
Typical IMP wall thicknesses
Here are some typical IMP wall thicknesses used for common building types:
| Building Use | Typical IMP Thickness |
|---|---|
| Office buildings | 2-3 inches |
| Retail stores | 2-4 inches |
| Healthcare facilities | 3-4 inches |
| Warehouses | 4-6 inches |
| Cold storage buildings | 4-6 inches |
These thicknesses are general guidelines only. The specific project requirements must be evaluated to determine the appropriate IMP wall thickness.
Structural performance
In addition to insulation value, the thickness of IMP walls affects their structural properties:
- Thicker panels have increased shear strength and stiffness to resist lateral and wind loads.
- Thicker panels have improved span capability between framing supports.
- Thicker panels provide higher shear bond strength for rooftop equipment, canopies, and other attachments.
Consult with the IMP manufacturer to determine the required thickness for adequate structural performance.
FRR and acoustics
Two other factors related to thickness are fire resistance rating (FRR) and acoustics:
- Thicker IMP walls improve fire resistance, as the foam core provides additional protection before the metal skins are exposed to fire.
- Thicker panels have higher sound transmission class (STC) values to block exterior noise. This is beneficial in buildings near airports or other noise sources.
Weight considerations
While thicker IMPs improve insulation and strength, they do become substantially heavier. Some weight comparisons for a typical 4×10 foot panel:
| IMP Thickness | Panel Weight |
|---|---|
| 2 inches | 420 lbs |
| 3 inches | 500 lbs |
| 4 inches | 595 lbs |
| 5 inches | 710 lbs |
| 6 inches | 820 lbs |
The structure must be designed to support the weight of thicker IMP wall panels. Handling and erection are also more difficult with heavier panels.
Cost comparison
The installed cost of IMP walls increases with thickness. Here is a relative cost comparison:
| IMP Thickness | Relative Cost |
|---|---|
| 2 inches | 1.0 |
| 3 inches | 1.15 |
| 4 inches | 1.35 |
| 5 inches | 1.50 |
| 6 inches | 1.75 |
The improved thermal, acoustical, and fire resistance performance often justifies the added cost of thicker panels. But budget is always a consideration.
Conclusion
Determining the optimal IMP wall thickness depends on many factors – climate, building use, codes, loads, fire rating, acoustics, weight, and cost. Thicker panels have higher insulation value and strength, but become much heavier and more expensive.
When designing the walls for your next IMP building project, carefully evaluate the requirements and consult closely with the manufacturer to choose the ideal thickness.
