PU foam strip Ø 40mm (open cell)

Joint foam strip Ø 40mm open-cell PU foam

For joints up to 35mm ✓ CFC- & HCFC-free ✓ Heat insulating ✓

Our foam strip in 40mm diameter is the largest foam strip we stock in metre lengths in our online shop. Made of open-cell polyurethane foam, the joint strips are light, soft and flexible and are very easy to work with. At the same time, the thick strips are perfectly suited for wide joints to be used as filling material. Our PU strips are UV-resistant and can therefore be used without further ado for expansion joints and construction joints in outdoor areas.

To be able to use the foam strips, the joints should have a width between 25mm and 35mm. In addition, the depth of the joint should be at least 60mm in order to be able to achieve a sufficient thickness of the sealant, which is necessary for an elastic joint. A foam strip has a significant effect on the optimum consumption of the sealant used, because the depth of the joint can be precisely limited by the foam strip. In addition, a joint strip ensures that the adhesion of the sealant to the outer sides is limited. This ensures optimal two-flank adhesion, which is very important for expansion joints.

Scope of delivery:
• 1x foam strip Ø 40mm open cell 1000mm length

TIP: With a cutter knife or large household scissors, the thick foam strips with a diameter of 40mm can be easily shortened.

Properties of our PU foam strip in Ø 40mm

Our foam strips made of PUR are UV-resistant and can therefore be used without hesitation for joints in outdoor areas. The strips can also be used for interior joints as filling material to limit the joint depth, because they are not only physiologically neutral, but also CFC and HCFC-free. Polyurethane is also resistant to chemicals and is characterised by good resistance to all materials that are common in the construction industry or in industrial sectors where joint sealing is a possibility. Only against acids and alkalis in high concentrations, as well as petrol, the resistance is moderate, so that continuous contact should be avoided. For the intended use of the foam strips, however, this hardly plays a role. PU foam strips are soft, flexible and stretchable and can be processed very easily, even if the joint width is smaller in places.

While the foamed polyurethane has a positive effect on the workability and insulating properties, this also has the disadvantage that the elastic foam strips cannot be used for joints that are subject to permanently high mechanical pressure. Constant pressure, for example in joints that are submerged in water, would put too much stress on the joint, causing the foamed material to compress. Due to the lack of pressure stability, this could result in the joint tearing. For such applications, we recommend the use of foam strips made of closed-cell polyethylene.

Technical data of the PU foam strip in 40mm

• Material: Polyurethane
• Colour: Grey
• Diameter: 40mm
• Recommended joint width: 25mm - 35mm
• Recommended joint depth: min. 60mm
• Density: 0.125g/cm³
• Shore hardness: 20 - 40
• Shrinkage hardness: min. 150 KPa according to DIN 53571
• Elongation at break: min. 150% according to DIN 53571
• Compression set: 25% - 35% in accordance with DIN 53572
• Temperature resistance: -30°C - +60°C
• Ageing resistance: Excellent
• UV resistance: Sufficient
• Water resistance: Sufficient
• Chemical resistance: Sufficient

NOTE: PU foam strips are only moderately resistant to petrol and concentrated acids or alkalis.

Processing of our PU joint strips with 40mm diameter

A joint strip is inserted into the joint before the joint is sealed. Our thick foam strips with a diameter of 40 mm and a length of one metre can be inserted very easily by hand. The flexible material can also be used very well in smaller joints or around radii. For corners, it is recommended to shorten the strip at the appropriate point and then start again with another piece. The 40mm strips are used as backfill material for joints between 25mm and 35mm wide. When choosing the depth of the joint, ensure that it is at least 60mm, as for joints this wide, the thickness will be approximately 12mm-18mm, which should be chosen depending on the width of the joint. For floor joints, the thickness of the sealant after curing should be 60%-100% of the joint width. For all other joints, for example wall connection joints or expansion joints of adjoining buildings, the recommended joint thickness is about 50% of the joint width. All conventional sealants that are commonly used for sealing joints can be used as sealants. Our high-quality Alcoxy-based silicones, for example, are ideal for this purpose. Silicones from other manufacturers, as well as painter's acrylics or powerful MS polymers can also be used for joint sealing, in which our polyurethane joint cords are used as joint boundaries.

Foam strips made of open-cell PU foam not only have the advantage that the joint is limited to the necessary depth, but also have very good insulation values, so that they are also used for the thermal insulation of joints. Especially in expansion joints and wall connection joints, the use of a joint strip can significantly reduce the heat loss of a thermal insulation, which has a noticeable effect on the energy efficiency of a property. However, it is important to ensure that the foam strips are not stretched too much when they are inserted. Even though our PU foam strips have a breaking elongation of more than 150%, too much elongation can cause gaps in the filling material, because the strips contract again over time depending on the elongation.

Application examples:
• Foam strips serve as joint filling material for a very precise limitation of the joint thickness
• Foam strips provide the two-flank adhesion necessary for expansion joints
• All conventional sealants such as acrylics, MS polymers or silicones can be used
• Thanks to the foamed polyurethane, our joint strips have an insulating effect on exterior joints
• By limiting the thickness of the joint, excessive sealant consumption is kept in check

Sealing joints should always be done at temperatures above freezing. This ensures that the elastic properties of the sealant are not affected by frost. For this reason, silicones or acrylics should be processed between +5°C and +40°C. Joint strips are usually inserted into the joint shortly before sealing, so that the same processing temperatures apply to them as to the sealant used. Damp or wet joint strips may not dry sufficiently in sealed joints, so they should always be stored and processed in a dry place.

NOTE: PU foam strips should be stored at temperatures between +5°C and +25°C in a dry location.