Decothane Root Resistant waterproofing system

Manufacturer: Sika 

Materials: Polyurethane 

The Decothane Root Resistant waterproofing system comprises of:

  • Decothane Root Resistant base coat and top coat – a root resistant, single-component, liquid-applied, moisture-triggered, aliphatic polyurethane membrane for use in the main waterproofing layer
  • Decothane detail coat – a root resistant, single-component, liquid-applied, moisture-triggered, aliphatic polyurethane membrane for use as a top coat in exposed areas  of the system (eg upstands)
  • Sika Reemat Premium Reinforced Mat – a non-woven, glass fibre reinforcing mat for use as reinforcement embedded in the polturethane layer while still wet, and available for use in strips to cover cracks, joints or details

BBA logo

Number: 06/4359
Issue date: 04/06/2019

ETA logo

Number: 20/1024
Issue date: 20/12/2020

Approved for use on

Biodiverse Green Roofs Inverted Roofs Protected Roofs Roof Gardens Warm Ballasted Roofs 

The Decothane Root resistant Waterproofing system is satisfactory for use in:

  • warm Ballasted Roofs
  • inverted Roofs
  • protected inverted roofs
  • green roofs
  • roof gardens
  • biodiverse specifications



Conctrete decks to which the system is to be applied must comply with the relevant requirements of BS 6229 : 2018, BS 8217 : 2015 and, where appropriate, NHBS standards2019, chapter 7.1. Attention is drawn to the requirements of these standards to ensure that reinforced concrete roof slabs are finished to an acceptable standard, allow free drainage of water and are allowed to dry prior to the installation of the waterproofing. When these conditions are not satisfied, approprate remedial treatment is essential.


25 Years 

Under normal service conditions, the system will provide a durable roof waterproofing with a service life in excess of 25 years.

Where the system is used in a fully protected specification and subject to normal service conditions, it will provide an effective barrier to the transmission of liquid water and water vapour for the design life of the roof in which it is incorporated.

In situations where maintenance or repair of any of the system components in the roof structure is necessary (eg protection layer or insulation), the durability of the membrane my be reduced. In these circumstances the Certificate holder should be consulted.

An estimate cannot be given for the life of green roof and garden specifications owing to the nature of use. However, under normal circumstances it should be significantly greater than for open coverings.

Installation Requirements

The system should only be installed by specialist roofing contractors who have been trained and approved by the certificate holder.

Puncture Resistance

P4 - roof gardens, inverted roofs and green roofs)

Most Compressible Substrate (eg insulation)

Fire Safety

When protected by an organic covering (eg. gravel or paving slabs) listed in the annex of Commission Decision 2000/553/EC the system is considered to achieve BROOF (t4) classification and so is unrestricted to the National Building Regulations.

In the opinion of the BBA, a roof incorporating the system will be unrestricted under the National Building Regulations in the following circumstances: a roof garden covered with a drainage layer of gravel 100mm thick and a soil layer 300mm thick, irrigated roof gardens and green roofs

When used for flat roofs with the surface finishes of bitumen-bedded stone chippings covered with whole surface to a depth of not less than 12.5mm or bitumen-bedded  tiles of non-combustible material, sand and cement screed or macadam, defined in approved document B of the Building Regulations , England and Wales, Appendix A, table 5 part iii or the Building Regulations Northern Ireland, Technical booklet E part IV table 4.6, the roof is deemed to be of classification BROOF (t4)

The designation of other specifications (eg on combustible substrates) or where the capsheet is exposed should be confirmed by: England and Wales — test or assessment in accordance with Approved Document B, Appendix A, Clause 1 Scotland — test to conform to Mandatory Standard 2.8, clause 2.8.1(1)(2) (1) Technical Handbook (Domestic). (2) Technical Handbook (Non-Domestic). Northern Ireland — test or assessment by a UKAS-accredited laboratory, or an independent consultant with appropriate experience.

If allowed to dry, the plants used may allow flame spread across the roof. This should be taken into consideration when selecting suitable plants for the roof. Appropriate planting irrigation and/or protection should be applied to ensure the overall fire rating of the roof is not compromised.

  • Downloads


Sika House
Miller Street

T : 01772 259781

Website disclaimer:

“The information contained in this Website is for general information purposes only. The information is provided by manufacturer members and their accreditation certifications and while we endeavour to keep the information up to date and correct, we make no representations or warranties of any kind, express or implied, about the completeness, accuracy, reliability, suitability or availability with regard to information or products. Any reliance you place on such information is therefore strictly at your own risk.

LRWA Is not an accreditation body and does not test products or have a role in determining whether a product or system is fit for purpose. An agrément certificate is only issued for a successful product or system following a detailed assessment including both laboratory testing and inspections by the certificate provider.”