Monarflex Moisture and vapour barriers

Monarflex Vapour control layers

What is a vapour control layer and where is it installed?

 Monarflex Monartight system  
A vapour control layer is a vapour tight or a vapour check membrane that is installed on the warm side (facing towards the liveable area) of a roof or on the inside of the exterior house wall. The function of a vapour control layer is to avoid moisture that builds up inside a house, to find its way to the insulation material, which then will absorb the moisture making the insulation material lose its ability to insulate.


What is air tightness?

Air tightness is absolutely essential if you want to achieve a healthy environment, reduce heating costs, eliminate heat loss and reduce CO2 emissions. It also protects the building envelope from harmful condensation in walls and roof spaces that can form mould, mildew and rot resulting in the decay of the construction and potentially leading to health risks.

Why air tightness?

Air tightness is the control of air leakage and heat loss through the building fabric and in particular at interfaces, joints & junctions It is therefore extremely important to provide an airtight seal within the internal building fabric that eliminates air leakage heat loss and unwanted condensation in the building fabric.

Why use a vapour control layer?

Effective Air tightness involves securing air leakage paths and therefore reducing the risk of condensation through warm air from the inside of the building coming into contact with cold surfaces in roofs and walls. The amount of moisture created in a typical family building is approximately 15 litres of water per day. If not ventilated away, the moist air will enter the building fabric and take with it heat that will eventually condense. In winter time this will often accumulate on the roofing underlay including roofs designed with vapour permeable membranes where the amount of condensation is higher than the membrane capacity .

Importance of application

In order to get air tight building envelope out of a Monarflex VCL it is important to recognize the fact that the accessories, as well as the installation process, play an equally important role as the vapour control layer itself.
When combining the different Monarflex accessories with the Monarflex VCL you ensure that a TOTAL protection system is formed that will assist the vapour control layer in providing the best air tightness.

Air tightness – building test

Air tightness testing is carried out by using a method known as a ‘blower door test’ in accordance with BS EN 13829. The measurement is taken by blowing air into the house via a particular door that is mounted in the main entrance. According to the air flow the air tightness can be defined. By the use of thermo graphic equipment, leakage paths can be identified.

Product range

The Monarflex product portfolio for vapour control layers covers all the needs for different applications ranging from ordinary houses with regular levels of water vapour to swimming halls with extreme water vapour build up.
Monarflex has a wide range of Vapour Control Layer.

The Vapour Control Layers are divided into to main groups

  • Vapour Check membranes - Multi purpose air barrier and vapour check membranes
  • Vapor Tight membranes - High performing vapour control layer and effective air barrier
Product Name Vapour tight Vapour check Weight g/m²  SD value - meter Reinforced grid
Monarvap SD2 95 2  
Monarvap SD2 RE   135 2
Monarvap SD5   95 5  
Monarvap SD5RE   125 5
Monarvap SD10   95  10  
Monarvap SD10RE   125 10
Monarflex® Elephant Skin   184 105  
Monarflex® MonarVap 200 Black   185 125  
Monarflex® Netofol 200VB   210 80
Monarflex® Monofilament 250   265 120
Monarfol® Super   320 150
Monarflex® Monarvap Reflex 110   110 150
Icopal Monarvap Reflex 200   190  250
Monarflex® Polykraft STD   80 ≥1500  
Monarflex® Reflex V-TEK   240  ≥1500
Monarflex® Reflex 275   300  ≥1500


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Monarflex contact details

Monarflex s.r.o.
Továrenská 1
943 03 Štúrovo

Slovak Republic

Phone + 421 36 7563865

UK & Ireland

Please visit the dedicated website at

Tel: 0161 8654444 (UK office)

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