• Sikafloor 21 N PurCem

Sikafloor 21 PurCem


A multi-component, water-based coloured polyurethane hybrid screed with self-smoothing properties. It has a smooth, matt, impervious, hard wearing surface and is typically installed at 3 - 6 mm thickness.

  • May only be used by experienced professionals
  • Used as a scratch coat primer, basecoat and wear coat layer in SikafloorPurCem system build ups, in areas of medium to heavy loading, high chemical exposure and abrasion
  • Good chemical resistance
  • High mechanical resistance
  • High glass transition point
  • Non tainting /odourless
  • VOC free and environmental friendly
  • Can be applied to substrates with high moisture content (7 days old or mature damp concrete)

Professional use only - from the 24th August 2023, adequate training is required before industrial or professional use of this product.

Should you require training, visit - https://www.safeusediisocyanates.eu/

Product customisation

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  • 250 char. max
Colour Group
£63.88(ex. VAT)
£76.66 (inc. VAT)
Please choose your colour
Available for Delivery (See Delivery Options Below)


Professional use only - from the 24th August 2023, adequate training is required before industrial or professional use of this product.

Should you require training, visit - https://www.safeusediisocyanates.eu/

Medium to heavy duty self-smoothing polyurethane screed.

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Environmental Information

  • Conformity with LEED v4 MRc 2 (Option 1): Building
  • Product Disclosure and Optimization – Environmental Product Declarations
  • Conformity with LEED v4 MRc 4 (Option 2): Building
  • Product Disclosure and Optimization - Material Ingredients
  • Conformity with LEED v2009 IEQc 4.2: Low-Emitting
  • Materials - Paints and Coatings
  • Complies AgBB for use in in indoor environment Test

Approvals & Standards

  • Polyurethane screed for concrete protection according to the requirements of EN 1504-2:2004 and conforms to the requirements of EN 13813: 2002, DoP 02 08 02 02 001 0 000002 1088, certified by Factory Production Control Body, 0086, certificate 541325, and provided with the CE-mark
  • EN1186, EN 13130, and prCEN/TS 14234 standards, and the Decree on Consumer Goods, representing the conversion of directives 89/109/EEC, 90/128/EEC and 2002/72/EC for contact with food stuffs, according to test report by ISEGA, 32758 U11 and 32759 U11, both dated December 6th, 2011. (Tests performed on Sikafloor -20/21/22/29 and 31 PurCem in standard and LP versions)
  • British Standards Specifications (BSS) acceptance for use in the UK
  • Campden and Chorleywood Food Research Association, Ref. S/REP/125424/1a and 2a, dated 8th February, 2012
  • Fire classification report according to EN 13501-1 from Exova Warrington Fire for Sikafloor-21 PurCem No.317047, dated 24th of March, 2012
  • Liquid water transmission rate test report from the Technology Centre, Ref. 15456 dated January 25th, 2012
  • Abrasion resistance tests performed by Face Consultants Ltd., according to BS 8204-2:2003, report ref. FC/12/3850, dated January 17th, 2012. (Tests performed on Sikafloor -20/21 PurCem)
  • Impact resistance values tested at PRA, Ref. nº 75221-151, dated January 11th, 2012
  • Slip resistance properties according to DIN 51130 tested at MPI (Materialprüfung und Entwicklung), test reports refs. Nº 12-6639-S/12 and 12-6641-S/12, dated August 7th, 2012
  • Thermal expansion coefficient and freeze-thaw cycle resistance performed at RWTH / IBAC, report nº M-1614 dated May 29th, 2012

Application Instructions

Substrate Quality / Pre-Treatment

The surface must be clean, dry and free of all contaminants such as dirt, oil, grease, coatings and surface treatments, etc. All dust, loose and friable material must be completely removed from all surfaces before application of the product, preferably by vacuum. Pull of strength shall not be less than 1.5 N/mm2. If in doubt apply a test area first.


Premix part A with a low speed electric stirrer and then add part B and mix for 30 seconds. For the colourpack version, premix part A neutral with a low speed electric stirrer and add part D to it. Mix until a uniform colour is achieved. Ad part B and mix for 30 seconds. Use a double paddle (axis) mixer and gradually add part C (aggregate) to the mixed resin. Allow part C to blend for further 2 minutes minimum, to ensure complete mixing and a uniform moist mix is obtained. During the operations, scrape down the sides and bottom of the container with a flat or straight edge trowel at least once (parts A+B+C) to ensure complete mixing. Mixing Tools Use a low speed electric stirrer (300 - 400 rpm) for mixing parts A and B. For preparation of the mortar mix use a double paddle mixer.


Prior to application, confirm substrate moisture content, relative humidity and dew point. As a scratch coat Sikafloor-21 PurCem can be applied using a steel trowel. As a body coat Sikafloor-21 PurCem can be applied using a toothed trowel or pin screed, to the desired thickness, or a steel trowel. Remove air with a spike roller. For further details please refer to the related system data sheet.

Cleaning of tools

Clean all tools and application equipment with Thinner C immediately after use. Hardened / cured material can only be mechanically removed.


Do not apply to PCC (polymer modified cement mortars) that may expand due to moisture when sealed with an impervious resin.

Always ensure good ventilation when using Sikafloor- 21 PurCem in a confined space, to prevent excessive ambient humidity.

Freshly applied Sikafloor-21 PurCem, must be protected from damp, condensation and direct water contact (rain) for at least 24 hours.

Protect the substrate during application from condensation from pipes or any overhead leaks. Do not apply to cracked or unsound substrates.

Always allow a minimum of 48 hours after product application prior to placing into service in proximity with food stuffs.

Products of the Sikafloor-PurCem product range are subject to discolouration when exposed to UV radiation. Extend depends on colour. There are no measurable losses of any properties when this occurs and it is a purely aesthetical matter.

Products can be used outside provided the change in appearance is acceptable by the customer. In some slow curing conditions, soiling of the surface may occur when opened to foot traffic, even though mechanical properties have been achieved. It is advised to remove dirt using a dry mop or cloth.

Avoid scrubbing with water for the first three days.

Product Details

Data sheet

For Use By
Professional Use
Interior / Exterior Use
Interior & Exterior
For Use On
Application Method
VOC Levels
Pack Size
Mixing Ratio
Part A : B : C - 1 : 1 : 5 (packaging size - 3.0 : 3.0 : 15) by weight
~ 1.93 kg/m2/mm
Recommended Thinner/Cleaner
Thinner C
Flexural Strength (at 20°C)
10 N/mm2 after 28 days at +23°C / 50% r.h.
Max. Application Temperature
Min. Application Temperature
Part A+B+C mixed: ~ 1.93 kg/l ± 0.03 (at +20°C)
Touch Dry
12 Hours
Layer Thickness
Scratch coat 1 -2 mm
Base- and wear coat 3 – 6 mm
Resistance to chemicals
Pot Life
+10°C ~ 35 - 40 minutes
+20°C ~ 22 - 25 minutes
+30°C ~ 15 – 18 minutes
+35°C ~ 12 - 15 minutes
Compressive Strength
50 N/mm2 after 28 days at +23°C / 50% r.h.
Base Type
Exterior / Interior Use
Exterior & Interior Use
Suitable For Use On
Application Method
Floor Coating Systems
Product Type
Hybrid Screed
Product Range
Maximum Overcoating Time
+10°C 72 hours
+20°C 48 hours
+30°C 24 hours
+35°C 24 hours
Minimum Overcoating Time
+10°C 24 hours
+20°C 24 hours
+30°C 12 hours
+35°C 12 hours
Shore D
Colour Family
Colour Family
Colour Family
Colour Family
Colour Family
Colour Family
Fire Rating
Fire classification report according to EN 13501-1 from Exova Warrington Fire

Customer agrees that before placing an Order, Customer has read and understood the most up to date Product Data Sheet for the Product. Where we have access to the Product Data Sheet from the manufacturer, we will either provide a copy on request, or include a link to the Product Data Sheet available on the manufacturer’s website. Customer further agrees that we have no liability for any errors or omissions contained within the Product Data Sheets. For more information, please see our Terms & Conditions of Sale.

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Sikafloor 21 PurCem is only available with the shipping and delivery timescales listed below - please do not contact our Customer Support Team with enquiries about alternative or earlier shipping and delivery times.

Saturdays and Sundays, as well as Bank Holidays, are not classed as working days.

Orders placed after the cut-off for this product will not be processed for earliest dispatch until 9am the next working day.

All delivery costs below are excluding VAT

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