Polyurethane Systems for building and industry

Optimum thickness for polyurethane: application conditions

The high insulating capacity of polyurethane is not achieved in construction with any other commonly used insulating materials. This special characteristic is due to the structure of small cells formed by the foam and to the composition of the insulating gas occluded in these cells. Thanks to this low thermal conductivity, polyurethane achieves the thermal insulation values required in the TBC with the minimum thickness, which allows a larger living area to be left, with the consequent economic benefit.

On the other hand, if polyurethane thicknesses similar to other materials are incorporated, higher thermal resistance and greater energy savings are achieved, which also results in an economic benefit for the end user.

espesor optimo del poliuretano 1.jpg

 

Thermal resistance

From the declared conductivity value, and knowing the thickness applied, it is possible to know the thermal resistance by applying the following ratio.

R = e / λ

Where:
R stands for thermal resistance, m²·K/W
e stands for thickness, mm
λ stands for  thermal conductivity, W/m·K

THICKNESS (mm)

λ
0.026 (W/m·K)

λ
0.028 (W/m·K)

λ
0.030 (W/m·K)

λ
0.032 (W/m·K)

30

1,15

1,05

1,00

0,90

40

1,50

1,40

1,30

1,25

50

1,90

1,75

1,65

1,55

60

2,30

2,10

2,00

1,85

70

2,65

2,50

2,30

2,15

80

3,05

2,85

2,65

2,50

90

3,45

3,20

3,00

2,80

100

3,80

3,55

3,30

3,10

110

4,20

3,90

3,65

3,40

120

4,60

4,25

4,00

3,75

Thermal resistance value in m²-K/W, depending on conductivity and thickness. For intermediate values, you can interpolate.

 

Equivalent thickness

The equivalent thickness of an insulation material is that which equals the thermal resistance of another insulation material whose thickness is known. That is to say, it is the thickness that makes both materials have the same insulating capacity. In order to calculate the equivalent thickness, it is necessary to equalize the thermal resistance of both products.

R = e1 / λ1 = e2 / λ2

Where:
R stands for thermal resistance, m²·K/W
e1 stands for thickness of material 1, mm
λ1 stands for  thermal conductivity of material 1, W/m·K
e2 stands for thickness of material 2, mm
λ2 stands for thermal conductivity of material 2, W/m·K

espesor optimo del poliuretano 2.jpg

 

Thickness measurement

The thickness of the projected polyurethane works shall be measured according to the Annex A of the UNE-EN 14315-2 Norm, by means of a graduated punch or a similar instrument whose diameter does not exceed 2 mm. 10 measurements will be taken every 100 m² projected, at a distance of over 200 mm. of any edge. If the width of the projected area is less than 450 mm, measurements must be taken at a distance of over 100 mm. of any edge. The declared thickness of the insulation installed shall be calculated as the arithmetic mean of all measurements taken.

In order to measure the thickness of injected polyurethane works, 10 measurements will be taken every 100 m² through the injection holes, measuring the total depth of the hole using  a metal tape and subtracting the thickness of the first sheet. The average thickness shall be calculated as the arithmetic mean of all measurements taken.

 

DOWNLOAD. Basic aspects you need to ask your polyurethane manufacturer

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