TermaTech TT21RS

TermaTech TT21RS

Please note that our stove range is now sold via our distributor, Specflue Ltd. The button link will take you to the dedicated site. For all enquiries, please visit the Specflue site.

The TT21RS wood-burning stove completes the experience of the elements with rounded Brazilian soapstone on a black stove.

The unique heat-storing properties of the soapstone are combined the soft shapes of the elegant cast iron door that closes with the help of two heat-resistant magnets. This avoids moving parts in the door construction, which guarantees a long service life and a maintenance-free function..

Please note that this model requires a Defra Kit to be Defra Approved.

Product code 69TT21RSB

Description

Click here to download the Technical Specifications sheet

The TT21 series meets all the desires and requirements of today’s modern consumer. High efficiency, environmentally friendly combustion, easy operation, and durable cast-iron details come together in a stylish, timeless Scandinavian design – all at a highly attractive price.

Design: Choose from different models, featuring steel sides and a top plate made of cast iron, heat-retaining soapstone, sandstone, or concrete stone. The TT21 series is available in different heights. Additional features such as extra heat storage, shaped floor plates, or a wood compartment door with or without fireplace tools can also be added.

The elegant door handle accentuates the clean design lines and remains cool to the touch. Combined with the unique door closing mechanism, which uses two heat-resistant magnets, this guarantees optimal ease of use and long-lasting durability.

A variety of accessories are available for the stove, including a handle made of powder coated black stainless steel and a wood compartment door with or without fireplace tools to complete the stove’s design.

The depth of the combustion chamber ensures clean, efficient burning, creating a large, glowing ember layer while preventing ash from swirling. The stove’s top plate, door, and combustion chamber floor are made from cast iron, enhancing durability and stability.

Combustion is easily controlled with a discrete air lever located below the cast-iron door, and the integrated start function makes the TT21 exceptionally user-friendly. The large ash drawer, equipped with a lid, allows for easy, clean ash removal when needed.

The TT21 also allows for direct connection of fresh or outside air to the combustion process, which is especially useful for new builds.

Additional information

Weight 176 kg
Dimensions L 419 x W 531 x H 1075 mm
Type of stove

Contemporary

Heat output

5kW

Fuel Type

Wood

Colour

Black with marbled soapstone

Nominal heat output

5kW

Heat range

3-7kW

Efficiency

81%

Energy rating

A+

DEFRA Approved

Yes

EcoDesign

Yes

clearSkies (level 1 - 5)

clearSkies 5

Depth (mm)

419

Width (mm)

531

Height (mm)

1075

Flue diameter

150

Weight (kg)

176

SKU 69TT21RSB

Schiedel Isokern Garden Fireplace Installation Guide

Thinking about transforming your outdoor living space with a premium volcanic pumice fireplace or outdoor kitchen? To help you prepare for a seamless installation, we’ve compiled the answers to the most common questions regarding safety clearances, UK planning laws, and environmental regulations.

Structural & Safety Clearances

Can I build my garden fireplace directly onto my timber decking?

No. Due to the substantial structural weight of these premium volcanic pumice packages—which range from 460kg up to 1,490kg fully built—they must never be placed on timber decking.

Instead, they require a flat, solid foundation. We strictly recommend a minimum 100mm thick reinforced concrete base to guarantee the completed structure won’t sink or slant over time.

How close can the fireplace be placed to wooden fencing or a pergola?

Because volcanic pumice is a highly effective, natural insulator, the exterior of the fireplace remains safe to touch. However, a precise buffer zone must be maintained between the structure and any combustible materials:

  • The Hale Outdoor Kitchen: Requires a minimum clearance of 100mm.
  • The Kingham & Standalone Fireplaces (500, 950, 1200 Models): Require a minimum clearance of 75mm.

I want to position the chimney near or through a pergola roof. How high should it go?

The chimney flue must completely clear the height of your pergola canopy to ensure exhaust smoke and sparks disperse safely away from your seating area.

If your design requires extra height to clear an overhanging beam line safely, additional chimney blocks can be purchased separately and added to the vertical stack during assembly. We also highly recommend adding a Rain Cap / Wave canopy to maintain a reliable upward draft and block weather down-drafts.

UK Planning Permission & Boundary Rules

Do I need formal Planning Permission from my local council to install a garden fire?

For the vast majority of residential homes, permanent brick or stone barbecues and outdoor fireplaces fall under Permitted Development rights (similar to garden outbuildings or enclosures). This means they do not require a formal planning application, provided your project meets specific layout criteria.

How close to my neighbor’s boundary line or fence can I build the fireplace?

This depends entirely on the total height of your completed structure (including the chimney capping):

  • Structures up to 2.5m tall: Can be positioned as close to your boundary fence or wall as you like (though we recommend a small gap to make rendering the exterior easier).
  • Structures taller than 2.5m: The entire unit must be shifted forward into your property line so that it sits more than 2 metres away from any boundary line or fence.

What are the absolute height limits if I move it more than 2 metres away from the boundary?

Once your fireplace is positioned safely past the 2-metre boundary zone, your Permitted Development allowances increase:

  • Your structure can go up to a maximum height of 3 metres for standard mono-pitch or custom flat profiles.
  • It can go up to a maximum height of 4 metres only if the structure features a dual-pitched (apex/A-frame) roof line.

Note: If your space is restricted and you cannot move a chimney taller than 2.5m at least 2 metres away from a boundary, you must submit a formal Householder Planning Application to your local council before starting construction.

Are there any extra restrictions if my fireplace is completely freestanding?

Yes. If you plan to install your garden fireplace as a standalone, freestanding unit (rather than building it flush against a solid masonry wall or as part of a fully supported outdoor kitchen layout), you must carefully consider the maximum height for wind safety:

  • Standard Kit Height: Our standard packaged kits are completely load-bearing and fully safety-tested to be freestanding at their delivered heights.
  • Adding Extra Chimney Blocks: While you can easily purchase extra chimney blocks to increase the height of your flue, we strongly advise against extending a freestanding chimney beyond 3 metres in total height without a professional structural review.
  • When to consult an expert: If your property is located in an exceptionally exposed or high-wind area (such as a coastal zone or an elevated hillside), or if your custom design calls for a highly extended freestanding chimney flue, you should consult a qualified structural engineer before building. They will assess your local wind load factors and advise if your specific site requires a deeper concrete foundation pad or specialized internal structural reinforcement.

Are there any other garden layout rules I need to worry about?

  1. No Front Yards: You cannot construct a permanent garden fireplace or structure on land forward of the front facade (principal elevation) of your home. It must be situated to the side or rear.
  2. The 50% Rule: The space occupied by the fireplace, outdoor kitchen modules, and any existing sheds/outbuildings must not collectively take up more than 50% of the total land area surrounding your original house.
  3. Designated Land & Listed Buildings: If your home is legally a Listed Building or sits within a Conservation Area, National Park, or Area of Outstanding Natural Beauty (AONB), permitted development rights are typically restricted or removed. You will need to check with your council before starting any stonework.

Environmental & Smoke Regulations

Can I use my garden fireplace if I live in a designated UK Smoke Control Area?

Yes. While the UK Clean Air Act regulates chimney smoke inside urban areas, unroofed outdoor garden fireplaces and barbecues are broadly exempt from domestic indoor chimney restrictions. However, you can still face local enforcement if your fireplace creates what the law defines as a “Statutory Nuisance.”

What is a “Statutory Nuisance” and how do I avoid it?

Under Section 79 of the Environmental Protection Act, if smoke, ash, or persistent fumes from your garden fire regularly blow directly into a neighbor’s property—preventing them from opening their windows, sitting outside, or hanging out laundry—the local council can issue an Abatement Notice.

To avoid this, always position your fireplace where prevailing winds won’t push smoke directly toward neighboring windows, and extend your chimney height if necessary to discharge smoke cleanly upwards.

What fuels am I legally allowed to burn?

To ensure a clean, efficient burn, you should strictly use clean, dry, and seasoned wood logs—ideally labeled with the Woodsure “Ready to Burn” logo, which certifies a moisture content below 25%.

Never Burn: Treated or painted waste wood, old pallets, plastic, or household rubbish. Burning these materials releases volatile, toxic chemicals into the air, creates heavy dark smoke, and leads to an immediate buildup of corrosive tar within your chimney structure.

All Termatech products achieve clearSkies Level 5 and are Defra Exempt.

This means that they achieve the highest possible ratings for wood burning stoves, therefore energy efficient with more fire and less smoke. Being Defra Exempt means they can be installed in Smoke Control Areas.