---
title: Optimum thickness of polyurethane according to insulation requirements
description: Designing each constructive solution with the optimum insulation thickness is the best strategy to get the most benefits at the lowest cost.
---

[Synthesia Technology- Polyurethane Systems](https://blog.synthesia.com/en)

# [Optimum thickness of polyurethane according to insulation requirements](https://blog.synthesia.com/en/the-optimum-thickness-of-the-polyurethane-according-to-insulation-requirements)

 Written by [Synthesia Technology](https://blog.synthesia.com/en/author/synthesia-technology) | 04 June 2019

Knowing the insulation needs of buildings is fundamental [**to improve their energy efficiency**](https://blog.synthesia.com/en/optimal-insulation/insulation-polyurethane-systems-ally-energy-efficiency) and so that they** make a more intelligent use of energy**. Therefore, designing their envelope with the optimum insulation thickness is the best strategy to get the most benefits at the lowest cost.

 

### **Interior insulation of facade**

- **Optimum thickness and insulation**: sprayed polyurethane foam; minimum thickness of layer: 30 mm. Minimum density: 35 kg/m3.

The available space determines and limits the thickness of the insulation applied. The best result is achieved by combining low thermal conductivity and low thickness [insulation systems](https://blog.synthesia.com/en/polyurethane-systems-in-buildings), such as polyurethane with reinforced or direct cladding based on laminated plasterboard as an interior finish.

### **Exterior insulation of facade**

- **Optimum thickness and insulation**: sprayed polyurethane foam; minimum thickness of layer: 30 mm. Minimum density: 35 kg/m3.

 

### **Median facade**

- **Sprayed polyurethane foam**: minimum thickness of layer: 30 mm. Minimum density: 35 kg/m3.
- **Optimum thickness and insulation of the protective layer**: polyurethane elastomer; polyurethane layer of variable thickness (1.5-3 mm), density 1,000 kg/m3 with coloration. It provides UV protection to polyurethane foam and increases waterproofness and consistency.

 

 

### **Filling of air gaps**

- **Optimum thickness and insulation**: low density injected polyurethane foam, 12 kg/m3 initial, being able to reach 18 to 25 kg/m3 applied and λ 0.038 W/(m • K) filled with a minimum thickness of 40 mm.

Before its application, it is important to check the continuity of the gap and the existence of a minimum thickness of filling.

 

### **Flat cover**

- **Optimum thickness and insulation**: polyurethane foam; minimum thickness of layer: 30 mm. Minimum applied density: 45 kg/m3 in covers to ensure impermeability.
- **Optimum thickness and insulation of the protective layer**: polyurethane elastomer; Polyurethane layer of variable thickness (1.5-3 mm), density 1,000 kg/m3 with coloration. It provides UV protection to the polyurethane foam and increases the impermeability of the cover.

  

 

### **Sloped cover**

- **Optimum thickness and insulation**: polyurethane foam; minimum thickness of layer: 30 mm. Minimum density: 45 kg/m3 in covers to ensure impermeability.
- **Optimum thickness and insulation of the protective layer**: polyurethane elastomer; Polyurethane layer of variable thickness (1.5-3 mm), density 1,000 kg/m3 with coloration. It provides UVA protection to the polyurethane foam and increases the impermeability of the cover.

   

 

The optimum polyurethane thicknesses can vary according to the **geographic area** where the building is located, so it will be necessary to **check the regulations** in this respect in order to use the appropriate values.

 

*Sources: Institute for the Diversification and Saving of Energy, IDAE.*

 

[View full post](https://blog.synthesia.com/en/the-optimum-thickness-of-the-polyurethane-according-to-insulation-requirements)

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