The Ultimate Guide to Isokern Double Module Chimney Systems
The Ultimate Guide to Isokern Double Module Chimney Systems: A Game-Changer for UK Homes
When it comes to chimney systems for UK homes, the Isokern Double Module (DM) Chimney System stands out as a premier choice for homeowners and installers seeking efficiency, safety, and ease of construction. Available through StoveSaver, this pumice-based system is designed to meet the unique demands of the UK market, offering unmatched performance for wood-burning stoves, open fires, and other heating appliances. In this comprehensive guide, we’ll explore the features, benefits, and practical advantages of the Isokern DM system, focusing on its speed of construction, safety features like distance to combustibles, and compliance with UK building regulations.
What is the Isokern Double Module Chimney System?
The Isokern Double Module (DM) Chimney System is a modular, pumice-based chimney solution developed by Schiedel, tailored for the UK’s diverse heating needs. It combines lightweight, highly insulating pumice blocks with a dual-layer design (inner flue and outer casing) to create a robust, efficient chimney system. Available in three variants—DM 36, DM 44, and DM 54—the system caters to a range of internal diameters (150mm, 180mm, 200mm, 300mm, and 345mm), making it suitable for everything from compact stoves to large open fireplaces.
The DM system is engineered for both new builds and retrofits, offering a versatile solution that aligns with the UK’s stringent energy efficiency and safety standards, particularly Document J of the Building Regulations. Its modular design and natural pumice material provide a balance of performance, durability, and installer-friendliness, making it a top pick for UK chimney projects.
Key Benefits of the Isokern Double Module System
The Isokern DM system leverages the unique properties of pumice—a lightweight, porous volcanic rock—to deliver a host of benefits tailored to the UK market. Here’s why it’s a standout choice:
1. Exceptional Thermal Insulation
Pumice’s natural insulating properties ensure that flue gases remain above the dew point, reducing condensation and soot build-up. This is particularly important in the UK’s variable climate, where cold, damp conditions can affect chimney performance. By maintaining optimal flue gas temperatures, the DM system enhances appliance efficiency, ensuring quicker heat-up times and better draft for wood-burning stoves and open fires. This aligns with Document L requirements, helping UK homes achieve higher energy efficiency.
2. Minimal Thermal Expansion
Unlike clay or concrete systems, pumice has a low coefficient of thermal expansion, meaning it experiences minimal expansion and contraction with temperature changes. This reduces the risk of cracking or joint failures, ensuring long-term durability. For UK homes with sporadic fireplace use, this stability is crucial to maintaining structural integrity over time.
3. Lightweight and Installer-Friendly
The DM system’s pumice blocks are significantly lighter than traditional materials like concrete, allowing a single installer to handle and assemble the system with ease. This reduces labour costs and simplifies installation, especially in retrofit projects or properties with limited access. The lightweight design also minimises the need for additional structural support, making it a practical choice for UK new builds and renovations.
4. Versatility Across Applications
With internal diameters ranging from 150mm to 345mm, the DM system is highly versatile:
DM36 (150mm): Ideal for smaller output inserts, stoves, and solid fuel/oil cookers.
DM44 (180mm, 200mm): Perfect for inserts, stoves, and small open fires.
DM54 (300mm, 345mm): Designed for larger appliances, such as Magnum firechests and open fires.
This range ensures compatibility with a variety of UK heating appliances, from modern wood-burning stoves to traditional fireplaces, offering flexibility for homeowners and architects.
5. Enhanced Safety and Stability
The DM system features staggered joints between inner flue blocks and outer casings, providing maximum stability and preventing structural weaknesses. Air gaps between the outer casing and flue minimise surface staining, enhancing longevity and aesthetics. These safety features make the system a reliable choice for UK homes, where fire safety and maintenance are top priorities.
Speed of Construction: A Major Advantage
One of the most compelling benefits of the Isokern DM system is its rapid construction process, which is a significant advantage in the UK’s fast-paced construction and renovation market. The system’s modular design and lightweight pumice blocks streamline installation, reducing project timelines and labour costs. Key factors contributing to its speed include:
Pre-Designed Components: The DM system includes starter flue blocks, offset blocks, and outer casings that fit together like a three-dimensional jigsaw. For example, assembling firechests and gathers can take less than an hour, indicating that the overall chimney construction is similarly efficient.
Single-Person Installation: The lightweight pumice blocks (e.g., DM 36 casing blocks weigh approximately 18–30kg) can be handled by one installer, eliminating the need for mechanical lifting equipment or multiple workers.
Simple Jointing System: Joints are sealed with Isokern lip glue (approximately 2mm thick), applied using a special bag for precision. This quick-drying glue ensures secure connections without lengthy curing times.
Simultaneous Assembly: The dual-layer design allows inner and outer blocks to be laid simultaneously with staggered joints, speeding up the construction process compared to traditional brick-built chimneys.
For UK installers, this efficiency is a game-changer, particularly for retrofit projects where minimising disruption is critical. The system’s rapid assembly also makes it ideal for new builds, where tight schedules are common.
Distance to Combustibles: Unmatched Safety and Flexibility
Safety is paramount in UK chimney installations, and the Isokern DM system excels with its flexible clearance requirements, which comply with Document J of the Building Regulations. The system’s design allows for minimal or even zero distance to combustible materials under specific conditions, offering significant advantages:
Zero Distance for Straight Rendered Chimneys: For straight rendered chimneys with a ventilated terminal (e.g., using an approved raincap), the DM system requires zero distance to combustibles. This means the chimney can be installed directly adjacent to wooden structures, such as roof timbers or wall studs, without additional clearance. This is a major benefit for UK homes, where space constraints are common, particularly in older properties or compact new builds.
38mm Distance for Offset Systems: For offset chimneys or systems without a ventilated terminal, a 38mm distance to combustibles is required. This applies to components like DM 36, DM 44, and DM 54 offset blocks, ensuring safe installation even in complex configurations. For example, when passing through a floor or roof, non-combustible materials like mineral wool can be used for sliding joints to maintain zero clearance for straight sections, but offset sections require the 38mm clearance to structural timbers or loose combustibles. Non-structural elements like floorboards, skirting boards, or architraves may contact the chimney, providing additional flexibility.
Compliance with Regulations: The system’s clearance requirements are rigorously tested and CE Certified to EN1858 (TUV Cert no. 0036 CPD 90219001), ensuring compliance with UK safety standards. This gives homeowners and installers peace of mind, knowing the system meets the highest safety benchmarks.
These clearance options make the DM system highly adaptable, allowing it to be installed in a variety of UK properties without compromising safety or requiring extensive modifications.
Compliance with UK Building Regulations
The Isokern DM system is designed to meet the stringent requirements of Document J, ensuring safe and efficient operation in UK homes. Key compliance features include:
Clearance from Combustibles: As noted, the system adheres to zero or 38mm clearance requirements, depending on the configuration, ensuring safe installation near combustible materials.
Construction Standards: The system requires a minimum of 100mm of brick, stone, or block masonry surrounding the chimney, providing structural integrity and fire resistance.
Termination Heights: The system supports proper chimney termination heights, such as 600mm above the ridge if within 600mm of the ridge, or 1000mm above the highest point of intersection with the weather surface, as per Document J.
Testing and Maintenance: Post-installation tests, such as those outlined in Document J, ensure the system is functioning correctly. A chimney notice plate must be fixed in the dwelling (ideally near the electrical consumer unit), and the chimney should be swept twice a year using a medium-density polypropylene brush to maintain performance.
These features ensure the DM system is not only safe but also future-proof, designed to last the lifetime of the dwelling with proper maintenance.
Practical Installation Tips for UK Installers
Installing the Isokern DM system is straightforward, thanks to its modular design and lightweight components. Here are some practical tips for UK installers, based on Isokern guidelines:
Foundation and Hearth: Ensure a suitable foundation and constructional hearth are in place, compliant with Building Regulations. For open fires, use a cast-in-situ concrete slab lintel or pre-stressed lintels to support the firechest.
Joint Sealing: Use Isokern lip glue for all joints, applying a 2mm-thick layer with the provided application bag. Remove excess glue to maintain a smooth surface and ensure a secure seal.
Offsets and Bends: For offset chimneys, use DM offset blocks (available for DM 36, DM 44, and DM 54) and ensure a 38mm clearance to combustibles. A maximum of two offsets (four bends) is allowed, with angles not exceeding 45° from vertical.
Ventilation and Termination: Use a ventilated terminal (e.g., approved raincap) for zero clearance to combustibles in straight chimneys. Ensure proper lead DPCs and flashings are installed, with weep holes above the tray for moisture drainage.
Post-Installation Curing: Allow the chimney to cure for at least 72 hours before use, starting with small fires for the first week to ensure proper setting.
These steps ensure a safe, efficient, and compliant installation, tailored to the UK’s building standards and climate.
Why Choose the Isokern Double Module for Your UK Home?
For UK homeowners and installers, the Isokern Double Module Chimney System offers a compelling combination of performance, safety, and practicality. Its high insulation, lightweight design, and rapid construction make it ideal for a range of applications, from energy-efficient wood-burning stoves to traditional open fireplaces. The system’s flexible clearance options—zero distance for straight ventilated chimneys and 38mm for offsets—provide unmatched installation flexibility, while its compliance with Document J ensures safety and reliability.
At StoveSaver, we’re proud to offer the Isokern DM system as a leading chimney solution for the UK market. With free delivery on all Isokern Liner Packs and individual items over £750.00, StoveSaver makes it easy to access this high-performance system. Whether you’re upgrading an existing chimney or building a new one, the Isokern DM system delivers the efficiency, safety, and ease of installation you need to enjoy your fireplace or stove for years to come.
For more information or to explore our range of Isokern products, visit StoveSaver or contact our team today.