How To Correctly Install And Use Extruded Polystyrene XPS Boards To Ensure Their Performance And Service Life?

Proper installation and use of extruded polystyrene xps boards are critical to maximising their thermal insulation, waterproofing, and other performance characteristics while extending their service life. This requires strict control across multiple stages, including pre-installation preparation, installation techniques, and post-installation maintenance. The following are specific operational guidelines and precautions:

1. Pre-installation Preparation: Substrate Preparation and Material Inspection

1. Substrate Surface Preparation

Cleaning and Levelling:

Remove dust, grease, loose mortar, and loose areas from the substrate (walls, floors, roofs), ensuring the surface is dry and firm (moisture content ≤10%).

Level uneven areas with cement mortar (error ≤5mm/2m). Round corners at阴阳角 (radius ≥50mm) to prevent hollow spaces after EPS board installation.

Special Substrate Treatment:

Concrete Substrate: If the surface is smooth, apply a bonding agent to enhance adhesion;

Aerated Concrete Walls: Apply a layer of crack-resistant mortar to level the surface, preventing rapid water absorption by the substrate that could cause the adhesive to fail.

2. Material inspection and pre-treatment

Quality inspection:

Verify the specifications of the extruded polystyrene boards (thickness, dimensional tolerance ≤ 1 mm), compressive strength (exterior walls ≥ 150 kPa, underfloor heating ≥ 200 kPa), and environmental certification (e.g., Ten-Ring Certification). Reject damaged, deformed, or moisture-affected boards.

Inspect the shelf life and performance reports of the adhesive, anchoring hardware (plastic expansion nails, effective anchoring depth ≥50mm), and finishing mortar.

Panel Pre-Treatment:

Cutting: Cut panels to design dimensions using a utility knife or specialized cutting machine; edges must be straight, with diagonal dimensional accuracy ≤2mm;

Panel layout planning: Start from the corners and lay the panels in a staggered pattern (staggered joints ≥ 1/2 panel length), avoiding vertical joints. Panels at wall corners must be interlocked (e.g., L-shaped joints).

II. Core Installation Process: Construction Key Points for Different Scenarios

1. Exterior Wall Insulation System Installation

Adhesive Application Process:

Adhesive Application: Use the ‘dot-and-frame method’ or ‘strip adhesive method,’ with an adhesive coverage area ≥ 40% of the panel surface (≥ 50% in severely cold regions). Leave a 50mm ventilation groove along the panel edges to prevent air pockets.

Fixing Method:

Immediately press flat with a straightedge after bonding to ensure flatness ≤3mm/2m and panel joints ≤2mm. If gaps exceed 2mm, fill with expanded polystyrene strips;

Install anchors after 24 hours (≥6 per square metre, increased to 8 for high-rise buildings), with anchor bolts penetrating the base wall ≥50mm. Densify anchors at corners, door/window openings, etc.

Surface treatment:

Apply the first layer of crack-resistant mortar (thickness 3–5 mm), embed alkali-resistant mesh fabric (lap width ≥100 mm), then apply the second layer of mortar to cover, with a total thickness controlled at 5–7 mm to prevent cracking.

2. Installation of underfloor heating insulation layer

Base moisture-proofing:

First lay moisture-proof film (overlap ≥100mm, sealed with tape) to prevent ground moisture from penetrating the extruded polystyrene boards and affecting insulation performance.

Panel Installation:

Install the extruded polystyrene boards (thickness ≥20mm, compressive strength ≥200kPa) with staggered joints, seal the board joints with tape to prevent the underfloor heating pipes from causing the boards to shift;

Pipe Fixing: Install pipe clamps on the extruded polystyrene boards at the designed spacing (150-200mm) to fix the underfloor heating pipes, preventing direct contact between the pipes and the boards that could cause local compression.

3. Roof/Basement Insulation Installation

Roof Insulation:

Before installation, create a levelling layer. After laying the extruded polystyrene boards with staggered joints, cover them with a protective layer (such as concrete slabs or metal sheets) to prevent UV radiation from accelerating ageing. Ensure proper drainage slope (≥2%) to prevent water accumulation.

Basement insulation:

Apply waterproofing membrane to the outer side of the panels (using hot-melt construction to avoid high-temperature damage to the extruded polystyrene boards). Extend the panels at wall corners 500 mm below ground level to prevent soil moisture intrusion. Apply crack-resistant mortar on the inner side for protection.

III. Key technical points: Details to prevent performance degradation

1. Joints and waterproofing treatment

Board joint sealing:

When the gap between boards is ≤2mm, fill with polyurethane foam sealant; when the gap is >2mm, cut strips of the same material to fill the gap tightly, then seal with sealant to prevent air convection from forming a ‘thermal bridge.’

Waterproofing Nodes:

Around door and window openings, extruded polystyrene boards must be wrapped (with mesh fabric extending 100 mm into the opening interior); additional layers of mesh fabric should be applied at eaves, canopies, and other areas to enhance crack resistance;

In humid areas such as bathrooms and kitchens, board joints must be coated with waterproof paint (e.g., polymer cement-based paint) to prevent moisture penetration.

2. Anchoring and wind load design

Enhanced measures for high-rise buildings:

For buildings over 20 storeys, anchorage components must be installed immediately after the extruded polystyrene boards are bonded, with the number of anchor bolts increased to 8–10 per square metre. Support brackets must be added to the bottom three layers to resist wind pressure (in coastal areas, wind pressure values must be calculated, and the spacing between anchor bolts must be ≤300 mm).

3. Fire Safety Measures

Flame Retardant Rating Requirements:

Public building exterior walls must use B1-grade (difficult to ignite) extruded polystyrene boards. During construction, keep away from heat sources, strictly prohibit welding operations near the boards, and ensure fire extinguishers are available on-site.

IV. Usage and Maintenance: Key Measures to Extend Lifespan

1. Daily Usage Precautions

Avoid Mechanical Damage:

Do not directly stack heavy objects (such as building materials) on the surface of the extruded polystyrene boards. In underfloor heating areas, avoid using sharp tools that could puncture the floor. When constructing above the roof insulation layer, protective boards must be laid.

Control environmental temperature:

The operating temperature range for extruded polystyrene boards is -50°C to 70°C. Avoid prolonged exposure to high-temperature environments (such as near industrial chimneys). If used in high-temperature scenarios, a fire-resistant insulation layer such as rock wool must be applied externally.

2. Regular inspection and maintenance

Exterior wall system inspection:

Inspect the walls annually for cracks or hollow areas (by tapping and listening for sounds). If panels are found to be loose, repair them promptly: remove old adhesive → apply a bonding agent → attach new panels → apply crack-resistant mortar.

Moisture-proof layer maintenance:

If leaks occur in basements or roofs, repair the waterproofing layer first, then replace the moisture-damaged extruded polystyrene boards (moisture-damaged boards have a thermal conductivity increase of over 30%), to prevent insulation failure.

3. Special Environment Measures

Freeze Protection in Cold Regions:

The exterior plastering mortar on the outer side of exterior wall extruded polystyrene boards must contain freeze-resistant additives. During winter construction, ensure temperatures are ≥5°C to prevent adhesive freezing and failure;

Mould prevention in humid and hot regions:

The surface of extruded polystyrene boards in bathrooms can be coated with anti-mould paint, and regular ventilation should be maintained to reduce air humidity (≤60%).

V. Industry Standards and Regulations Reference

National Standards:

《Technical Standards for External Wall Insulation Engineering》 (JGJ 144-2019): Specifies the bonding strength and wind resistance requirements for the installation of extruded polystyrene boards on exterior walls;

‘Technical Procedures for Radiant Floor Heating’ (JGJ 142-2012): Specifies the compressive strength and installation requirements for extruded polystyrene boards used in radiant floor heating systems.

Construction and Acceptance:

After installation, the thermal insulation system must be tested for impact resistance (no cracking in a 3J impact test) and adhesive strength (≥0.1 MPa), and records of concealed work acceptance must be kept (e.g., anchor bolt depth, board joint treatment).

Summary

The installation and use of extruded polystyrene boards must adhere to the principle that ‘proper substrate preparation is the foundation, proper bonding and anchoring are critical, waterproofing and fireproofing are essential, and maintenance and care are key to extending service life.’ Through standardised construction practices (e.g., staggered joint installation, sealing treatment) and scientific maintenance (preventing damage, controlling environmental conditions), the thermal insulation performance can remain stable over the long term (thermal conductivity annual decay ≤1%), with a service life exceeding 30 years, fully leveraging its energy-saving and structural protection benefits.