DIBLU POLYSTYRENE 220MM / PACK 50 PCS

220MM POLYSTYRENE DOWEL

A 220mm polystyrene dowel is an essential fastener in External Thermal Insulation Composite Systems (ETICS), used to mechanically anchor expanded polystyrene (EPS), extruded polystyrene (XPS) or, in some cases, mineral wool to substrates such as concrete, solid brick, hollow brick, BCA or other building materials. Designed to provide a stable and durable fixing, this dowel resists external forces such as wind, thermal expansion or the weight of the thermal insulation system and is ideal for insulation thicknesses thinner than those covered by 240mm, 260mm or 300mm dowels.

Detailed description

1. Composition and materials

• Main body: Made of high quality polypropylene (PP) or polyethylene (PE), sometimes reinforced with fibres to increase mechanical strength. The plastic material is chosen to minimise thermal bridging, reducing heat loss and improving energy efficiency.
• Fixing Nail: Available in galvanised steel for superior corrosion resistance and solid anchorage, or reinforced plastic for lighter applications. Metal nails are preferred in hard substrates or demanding environmental conditions, and heat-capped designs reduce heat transfer through the nail.
• Flange (rosette): The upper part of the dowel, with a standard diameter of 60-65 mm, which presses the polystyrene board against the substrate surface. The flange evenly distributes the pressure to prevent damage to the insulating material.
• Expansion Zone: Located at the bottom, this zone expands into the backing material to provide a firm hold. Some designs include multiple expansion zones, effective in porous or hollow materials such as cavity brick.

2. Dimensions and technical specifications

• Overall length: 220 mm, suitable for 8-16 cm thick polystyrene boards, taking into account the adhesive layer (5-10 mm) and any additional layers (e.g. existing plaster).
• Diameter: The body of the dowel is usually 10 mm in diameter, compatible with standard drill bits.
• Anchoring depth: Minimum 50 mm into the substrate material (concrete, brick, etc.), according to pull-out strength standards. The drilled hole must be 10 mm deeper than the anchorage length for correct fixing.
• Pull-out strength: Depends on the type of substrate, e.g. may exceed 1 kN in concrete, but is lower in BCA or hollow brick, where specialised designs may be required.

3. Uses and applications

The 220 mm dowel is mainly used for:

• Fixing thermal insulation boards in façade systems, both new build and refurbishment, where insulation thickness is relatively thin.
• Various substrates: concrete, solid brick, hollow brick, BCA, porous concrete or, in specific cases, wood/OSB (with suitable screws).
• Low rise buildings (under 25-50 m, depending on regulations), where 4-6 dowels per square metre are recommended, according to the technical design.
• Plinth area: For extruded polystyrene used at the plinth, dowelling should start at least 30 cm above the ground to avoid contact with moisture.

4. Advantages

• Thermal efficiency: The plastic material reduces thermal bridges, contributing to the energy performance of the building.
• Mechanical resistance: Provides a stable hold even in windy conditions or temperature variations.
• Versatility: Compatible with most substrates and insulation types.
• Quick installation: Installs easily with a rotary hammer for drilling and a hammer for hammering the nail, without complex tools.
• Durability: Resistant to corrosion (galvanised nails) and degradation caused by moisture or chemical agents.

5. Installation instructions

1. Surface preparation: The polystyrene sheets are glued with special adhesive and left to harden (24-48 hours).
2. Drilling: Use a 10 mm drill bit to create a hole through the polystyrene and a minimum of 50 mm in the substrate. The hole should be 10 mm deeper than the anchor length.
3. Inserting the dowel: Insert the body of the dowel until the flange touches the surface of the polystyrene sheet.
4. Fastening the nail: Tap the nail (metal or plastic) with a hammer or screw it in until the flange presses firmly against the plate without deforming it.
5. Covering: Cover the flanges with reinforcing mesh and layers of decorative plaster.

6. Recommendations and standards

• Number of dowels: Minimum 4-6 dowels/sq.m for buildings under 50 m, according to project requirements.
• Length calculation: Thickness of polystyrene + thickness of existing adhesive/plaster + minimum 50 mm for anchorage.
• Certifications: Choose dowels with European Technical Approval (ETA) for compliance with building standards.
• Correct installation: Avoid excessive tapping, which can damage the polystyrene board, or insufficient drilling, which reduces strength.

7. Special features of the 220 mm dowel

• Optimal for thin insulation thicknesses (8-16 cm), common in renovations or constructions with moderate thermal requirements, such as single-family houses or low-energy buildings.
• The 220 mm length allows fixing into substrates with minimal additional layers (e.g. 1 cm old plaster).
• Some models include depth gauges or optimised design for quick installation.

8. Limitations and cautions

• Brittle substrates: In very porous or weak materials (e.g. porous BCA, old brick), pullout resistance may be reduced, requiring specialised tests or dowels.
• Incorrect assembly: Too wide a hole or insufficient anchorage compromises fixing.
• Compatibility: Check compatibility with the type of substrate and insulation thickness to avoid using too short a dowel.

9. Comparison with 240 mm, 260 mm and 300 mm dowels

• Length: The 220 mm dowel is shorter than 240 mm (by 20 mm), 260 mm (by 40 mm) and 300 mm (by 80 mm), making it suitable for insulation thicknesses of 8-16 cm, compared to 10-18 cm (240 mm), 12-20 cm (260 mm) or 15-25 cm (300 mm).
• Use: Ideal for thin insulation projects, reducing costs and installation time compared to longer dowels.
• Strength: Similar performance, subject to minimum anchorage depth (50 mm). All are versatile, but the 220 mm dowel is preferred in applications with less demanding thermal requirements.

Conclusion

The 220 mm polystyrene dowel is a practical and efficient solution for fixing thermal insulation boards in façade systems, ideal for thin insulation thicknesses (8-16 cm). With a design that minimises thermal bridging and provides mechanical strength, this dowel is perfect for renovations, single-family houses or buildings with moderate energy requirements. Choosing a certified model and following the installation instructions guarantees the durability and performance of the thermal insulation system.