Diasen Diathonite Thermostep.047 Screed
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Product Overview
Main purpose
Breathable non-combustible internal insulation and acoustic screed for ground or separating floors. Also as lightweight external insulation to insulate the rooms below a flat concrete roof or roof terrace.
Use it on
Internal ground floor concrete slabs or onto compacted foam glass aggregates with soil underneath. Can also be used externally on flat concrete roofs and roof terraces. With embedded steel reinforcing mesh, it can be applied to wooden or metallic surfaces and insulation panels.
Overview
Diathonite Thermostep.047 is a fibre reinforced lightweight insulating lime and cork-based floor screed. Typically applied over rigid concrete slabs or glass foam aggregates, it is ideal for the insulation of floors, ceilings and ventilated roofs which have concrete floors. Made of natural lime, cork, clay and diatomaceous earth powder, it is completely natural, highly-breathable, non-combustible and mould resistant. It is very workable and can be mixed with a mechanical mixer then hand applied with a trowel, or sprayed-on with a suitable plastering machine.
Where to use it
Diathonite Thermostep.047 can be used internally on ground floor concrete slabs or on to compacted foam glass aggregates with soil underneath. It can also be used externally on flat concrete roofs and roof terraces to provide external insulation for the rooms below.
Diathonite Thermostep.047 is typically applied in one 50-60mm layer but greater thicknesses (up to 200mm) can be achieved in multiple 40-60mm layers.
A typical ground floor installation consists of the following layers:
- Floorboards, flagstones or tiles
- Diathonite Thermostep.047 (40-200mm thick)
- Geotextile breather membrane
- Compacted foam glass aggregates (100-200mm deep)
- Geotextile breather membrane
- Ground soil
When Diathonite Thermostep.047 is installed over wooden/metallic panels or insulating panels, the surface must be primed first with Diasen Aquabond Primer. To help reduce the effects of movement on more flexible substrates like these, a stainless or galvanised steel reinforcing mesh should be embedded into the screed at 50% of the total depth to prevent cracks.
The suitable type and thickness of reinforcing mesh should be calculated by a structural engineer based on the expected use of the floor and the load exerted upon it.
Diathonite Thermostep.047 can be used in combination with underfloor heating. The heating pipes should be installed on top of the screed and they must not be embedded within it.
If there are any other pipes embedded in the screed, there must be at least 30mm of screed over the top of them and a galvanised steel or stainless steel mesh must be used to reinforce the area.
What it does
Diathonite Thermostep.047 improves the acoustic and thermal performance of the floor whilst maintaining high levels of breathability. It assists in regulating moisture thanks to its high capillarity and low vapour resistance. It is also highly mould resistant thanks to lime's high alkalinity. It also offers excellent fire resistance with a fire class A1 non-combustible rating. It is very workable and can be mixed in a mechanical mixer, applied by hand with a trowel, or it can be sprayed on with a suitable plastering machine.
The mixed screed has an excellent workable consistency due to its enrichment with natural fibres. The fibres help the screed hold its shape and provide strength once it sets. Once fully set it has a compression strength of 5N/mm²
It can be used internally or externally and can be finished with floorboards, tiles, or natural fibre carpet with a suitable breathable underlay.
Why we love it
Diathonite Thermostep.047 has superior thermal properties than its predecessor, Diathonite Screed. Containing only natural materials and qualifying for LEED points, Diathonite Thermostep.047 can be used in projects with strict environmental requirements.
It is non-combustible and does not emit smoke so will improve the fire safety of the building.
Made with totally natural materials including cork, natural hydraulic lime, clay and diatomaceous earth powder, Diathonite Thermostep.047 keeps the floor breathable and provides humidity balance. It is ideal for new builds and retrofits, including Heritage and Listed buildings.
It can be mixed straight from the bag with clean water to create a consistent mixture with excellent workability. The materials used make it lightweight, easy to work and an excellent insulator. It also dries much faster than a traditional lime-based screed.
Experienced builders can install it without special training.
How it works
Diathonite Thermostep.047 has an excellent low thermal conductivity, is highly vapour open (breathable) and is capillary active. So whether it is used over a concrete slab or in combination with glass foam aggregates with bare soil underneath, it provides excellent thermal benefits, maintains breathability and provides comfort to the building occupants.
Hints and Tips
Application temperature must be between +5°C and +30°C During summer season, apply the product during the cooler hours of the day, away from sun. The material is workable for about 30 - 40 minutes (this may vary depending on temperature and humidity).
Features
- Breathable
- Lightweight
- Good compressive strength
- High flexibility
- Contains only natural materials
- Fire Class A1 / non-combustible
Benefits
- Ensures excellent thermal comfort and humidity balance compared to a concrete screed
- It is four times lighter than a traditional floor screed
- High compression strength 5N/mm²
- With thermal conductivity of just 0.047W/mK, it is five times more insulating compared to conventional sand-cement screeds.
- Highly breathable with a vapour resistance factor (µ) of just 4
- Does not burn or smoke; helps improve fire safety of the building.
- DOP and UKCA certified
- Versatile. Can be applied to any depth in layers of 40-60mm.
- With a high quantity of light-weight cork, it minimises weight related stresses on the building making it ideal for retrofit of older buildings.
Questions
There are currently no questions and answers published for this product
Technical Details
Key Technical Data
Installation Guide
Find an installerMixing
Mix the product in a concrete/cement mixer. It is not suitable for mixing by hand. Add 12.5 litres of water per bag of Diathonite Thermostep.047.
Mix for approximately 4-5 minutes in the cement mixer. It is fundamental not to exceed mixing time. Do not mix the product by hand. Never add external compound to the product. Never add anti-frost products, cement or aggregates to the mix. For spray application with a suitable plastering machine, the nozzle of the applicator gun should be removed. The settings of the machine may vary depending on the type of machine being used. We recommend contacting the machine’s manufacturer or our technical team for assistance with settings. Also, check with our technical team for the suitability of the plastering machine; traditional screed pumps are not compatible.
The material is workable for about 30 - 40 minutes (this may vary depending on temperature and humidity).
Application
The ambient temperature during application must be between +5°C and +30°C. During summer or very warm weather, apply the product during the cooler hours of the day, away from sun. You may need to mist the surface with water prior to applying the screed.
Use timber battens no more than 2m apart set at the appropriate height to mark the required thickness of screed. Ensure the battens are perfectly level. Apply Diathonite Screed by filling the area between the battens. Levelling of the screed should be done with an aluminium straight edge in contact with the timber battens. Use smooth and continuous movements to make the screen flat and in line with the tops of the battens. As you proceed it is recommended to use a trowel to smooth and compact the surface.
The thickness of each layer must not exceed 60mm. For greater thicknesses, use multiple layers. When pipes are buried in the screed, stainless steel or galvanized reinforcement mesh must be used. The piping must always be covered with at least 30mm of screed, and the mesh must be positioned directly above the piping. The thickness and the type of metal reinforcement mesh should be calculated depending on the expected loads on the floor (refer to a structural engineer or contact us for assistance).
For application over wood or metal panels, it is necessary to use a galvanized metal reinforcement mesh every time regardless of screed thickness required.
Finishing
Diathonite Thermostep.047 should be completely dry before any final finish is installed. Dry screed can be covered with ceramic, terracotta, stone or tiles. The screed can also be finished with glued parquet flooring after at least 28 days of drying (depending on screed thickness and environmental conditions).
If the screed is too rough, the surface can be sanded and treated with Watstop to consolidate and stabilise the sanded surface prior to the final finish being applied.
Diathonite Thermostep.047 can be coated with liquid waterproofing or Diasen coatings without the use of primers.
Drying
At 23°C and 50% relative humidity, 50mm of Diathonite Thermostep.047 will dry in approximately 28 days. Drying time is influenced by humidity level and temperature and may significantly change. For thicknesses over 50mm, allow an additional 7-10 days for each 25mm of thickness.
Diathonite Thermostep.047, while curing, should be protected from ice, direct sunlight and wind to reduce the risk of cracks.
Under high temperatures, direct sunlight or strong wind you may need to wet the plaster for 2-3 days after the application (refer to our technical team for advice).
Once the application has been completed, leave at least 48h before walking over the screed.
Hints & Tips
All application/yield figures quoted are based on application to a smooth level surface.
For external applications, it is important to create expansion joints at regular intervals to reduce the risk of cracks on the finishing coat. Always create an expansion joint over each existing expansion joint underneath the screed.
Create suitable expansion joints where there are changes in the supporting material. E.g. at fixed elements like pillars, partitions, doors or thresholds etc. In special cases where the floor may flex due to wide distance between pillars or high loads, always use stainless steel or galvanized reinforcement mesh to reinforce the Diathonite Thermostep.047.