Larsen SLC 1550 Flex 20kg
Flexible Self Levelling Compound
Larsen SLC 1550 Flex provides a smooth and level base before installing a finished floor covering.
Its fibre-reinforced formulation combines strength with additional flexibility. Therefore, it works well where a standard rigid levelling compound may not suit the substrate.
The compound is also protein-free. As a result, it suits a wide range of domestic and commercial floor preparation projects.
3-50mm in One Application
SLC 1550 Flex can be applied from 3mm up to 50mm thick in one application.
Therefore, installers can use it for both minor floor correction and deeper levelling work.
For applications above 30mm, Larsen recommends consulting its technical department.
Ideal Over Underfloor Heating
Larsen specifically approves SLC 1550 Flex for use over suitable underfloor heating systems.
The fibre-reinforced formulation helps the compound cope with the temperature changes found in heated floors.
When applying over underfloor heating, Larsen also requires suitable perimeter expansion material. Always follow the current installation instructions.
Browse our Water Underfloor Heating range for compatible heating products.
Fibre-Reinforced Fiberflex Technology
SLC 1550 Flex uses Larsen’s Fiberflex microfibre technology.
Millions of reinforcing fibres help create an internal support structure within the compound.
As a result, the finished layer provides high flexural strength and improved resistance to cracking.
Fast Drying Floor Preparation
Time matters on flooring projects.
Larsen SLC 1550 Flex accepts light foot traffic after approximately 2-4 hours.
Floor coverings can normally follow after 24-72 hours. However, drying time depends on depth, substrate and site conditions.
Therefore, the product works well for fast-track renovation projects.
Suitable Substrates
Larsen SLC 1550 Flex can suit several correctly prepared substrates.
These include:
- Concrete
- Sand and cement screeds
- Suitable timber floors
- Existing ceramic tiles
- Existing resilient flooring
- Properly prepared renovation substrates
The floor must remain clean, dry and structurally sound.
In addition, remove grease, oil, paint and contamination before applying the compound.
Correct Priming Is Important
Correct priming helps create a strong bond.
For normal concrete and screed, Larsen recommends its Acrylic Primer diluted 1:1 with clean water.
Very porous floors may need an additional neat coat.
Timber substrates require a neat coat of Acrylic Primer after suitable preparation.
Use Larsen Acrylic Floor Primer 500ml before applying SLC 1550 Flex where the specification requires it.
For difficult or low-absorbency surfaces, consider Larsen Prime Grip 360 where suitable.
Mixing Larsen SLC 1550 Flex
Add approximately 3.75-4.25 litres of clean water to each 20kg bag.
Then mix with a heavy-duty drill and suitable paddle for around one to two minutes.
Alternatively, installers can use a suitable continuous mixer or pump.
Do not add excessive water. Too much water can reduce the finished strength.
Easy Pour or Pump Application
Pour or pump the mixed compound onto the prepared floor.
SLC 1550 Flex will then flow and level across the substrate.
If required, use a trowel or spiked roller to release trapped air.
Complete this stage within around 5-10 minutes of application.
Approximately 30-Minute Working Time
The published pot life is approximately 30 minutes at 20°C.
Therefore, prepare the floor before mixing.
Also, organise tools and materials in advance.
This helps the installer work continuously once mixing starts.
Coverage per 20kg Bag
One 20kg bag covers approximately 2.5-3m² at 5mm thickness.
Coverage changes as the application depth increases.
Therefore, always calculate the required quantity against the actual floor area and average depth.
Suitable Floor Coverings
Once fully dry, SLC 1550 Flex provides a suitable base for many floor coverings.
These include:
- Ceramic tiles
- Porcelain tiles
- Natural stone
- Vinyl
- LVT
- Carpet
- Resin coatings
- Other compatible resilient floor finishes
However, SLC 1550 Flex is not designed as a final wearing surface.
Domestic and Commercial Applications
Larsen designed SLC 1550 Flex for both domestic and commercial floor preparation.
Typical applications include:
- Homes
- Extensions
- Renovations
- Kitchens
- Bathrooms
- Offices
- Schools
- Hospitals
- Commercial buildings
- Underfloor heating projects
Therefore, it provides a versatile option for both installers and flooring contractors.
Technical Specifications
| Specification | Details |
|---|---|
| Brand | Larsen Building Products |
| Product | SLC 1550 Flex |
| Pack Size | 20kg |
| Type | Fibre-Reinforced Self Levelling Compound |
| Application Depth | 3-50mm |
| Coverage | Approx. 2.5-3m² at 5mm |
| Water Requirement | 3.75-4.25 litres per 20kg |
| Pot Life | Approx. 30 minutes at 20°C |
| Light Foot Traffic | 2-4 hours |
| Full Traffic | 1-2 days |
| Floor Coverings | Approx. 24-72 hours |
| Application Temperature | +5°C to +30°C |
| Compressive Strength | Greater than 25MPa |
| Flexural Strength | Greater than 7MPa |
| Shrinkage | Less than 0.06% |
| Classification | EN 13813 CT-C25-F7 |
| Colour | Grey |
| Shelf Life | 6 months in unopened packaging |
| Underfloor Heating | Suitable |
| Final Wearing Surface | No |
Why Choose Larsen SLC 1550 Flex?
This compound combines several useful features within one bag.
Benefits include:
- 3-50mm application depth
- Fibre-reinforced formulation
- Suitable over underfloor heating
- Fast drying
- Light foot traffic after 2-4 hours
- Approximately 30-minute working time
- Suitable for difficult substrates
- Suitable over correctly prepared timber
- Protein-free formulation
- Pump or hand application
- High compressive strength
- Suitable for domestic and commercial projects
Why Buy From Kudos Trading?
Kudos Trading supplies Larsen floor preparation products alongside complete underfloor heating systems.
Therefore, installers can source the levelling compound, primer and UFH components from one supplier.
We hold SLC 1550 Flex in stock for fast UK delivery. In addition, customers can collect directly from our Nottingham warehouse.
Frequently Asked Questions
Is Larsen SLC 1550 Flex Suitable for Underfloor Heating?
Yes.
Larsen specifically approves SLC 1550 Flex for suitable underfloor heating systems.
Always follow the manufacturer’s preparation and expansion-joint guidance.
How Thick Can Larsen 1550 Be Applied?
Apply the compound between 3mm and 50mm.
For depths above 30mm, Larsen recommends seeking technical advice.
How Much Does One 20kg Bag Cover?
One 20kg bag covers approximately 2.5-3m² at 5mm.
Deeper applications will reduce the coverage per bag.
How Much Water Do I Add?
Use approximately 3.75-4.25 litres of clean water per 20kg bag.
Do not add extra water to increase flow.
How Quickly Can I Walk on It?
Light foot traffic is normally possible after 2-4 hours.
Site temperature, depth and conditions can affect this time.
When Can I Install the Floor Covering?
Larsen states approximately 24-72 hours.
However, the exact time depends on compound depth, substrate and site conditions.
Can I Use Larsen 1550 on Timber Floors?
Yes, on suitable stable timber substrates.
However, the floor must remain rigid and correctly prepared.
Larsen also provides specific priming and plywood requirements for timber installations.
Does Larsen 1550 Need Primer?
Yes, suitable substrates require the correct preparation and primer.
For normal concrete and screed, Larsen specifies Acrylic Primer diluted 1:1 with clean water.
Can Larsen 1550 Be Pumped?
Yes.
Installers can pour the product manually or apply it using suitable pumping equipment.
Can I Leave Larsen SLC 1550 as the Finished Floor?
No.
The product creates an underlayment for a suitable floor covering. It does not provide a final wearing surface.
Related Products
- Larsen Acrylic Floor Primer 500ml
- Larsen Prime Grip 360 1kg
- Levelling Compounds & Tile Adhesives
- Kudos Trading Tile Backer Board 10mm
- 16mm PE-RT/AL/PE-RT Underfloor Heating Pipe
- XPS 400 Underfloor Heating Insulation Panels
Next Working Day Delivery
We hold our products in stock across our UK warehouses, including our 7,000 sq ft Nottingham warehouse.
Order before 12:00pm for tracked next-working-day delivery.
We use DPD for our tracked delivery service.
Delivery options and charges depend on your postcode.
Collection Available
You can also collect your order from our Nottingham location.
You can also enjoy a free tea or coffee while you visit.

