A professionally fitted vapour barrier is vital for all flat roofs

A vapour barrier is very important for a flat roof – it protects the insulation against moisture from inside the building. In this way, the vapour barrier prevents the appearance of damp stains, leaks, mildew and damage to the roof structure. But which vapour barrier should you ideally choose? And what do you need to bear in mind when installing it? Find out more by reading this article.

Protecting the warm side

A vapour barrier protects the insulation material against moisture present in the building. It is therefore only logical that this vapour barrier should be fitted to the warm side of the insulation, which is the surface facing the interior space. The vapour barrier serves several important purposes in this part of the building:

  • The vapour barrier makes the roof airtight
  • It ensures that water vapour cannot attack the insulation
  • It maintains a consistent insulation value
  • A vapour barrier can also be used as a temporary rainproof covering during construction work

Which vapour barrier should I choose?

The choice of vapour barrier depends mainly on the air humidity level inside the building. It goes without saying that, in this respect, there is a big difference between a car dealer showroom and a swimming pool. Not all types of buildings need the same moisture protection on the warm side of the construction.

The different air humidity levels in the interior climate are subdivided into four categories:

Indoor climate class Description Examples
I Buildings with little or no permanent moisture production – Showroom – Warehouses for dry goods
II Buildings with limited moisture production per m³ and with good ventilation – Sports halls – Large homes – Shops
III Buildings with substantial moisture production per m³ and with moderate to sufficient ventilation – Buildings with RH < 60% – Small homes – Restaurants – Hospitals – Buildings with limited air conditioning
IV Buildings with high moisture production – Buildings with RH > 60% – Swimming pools – Moist production and storage halls: laundries, breweries

*RH: Relative Humidity – Source: TV 215 Table 12

High quality expertise makes it easier to choose the right vapour barrier

Is there another vapour barrier that is suitable for every interior climate class? No, definitely not. In fact, the most important thing is that a vapour barrier is fitted professionally and according to the current standards. Only a vapour barrier that is perfectly fitted can guarantee the following properties:

  1. Maximum protection for the insulation material
    The insulation is fully “sealed” between two waterproof bituminous layers. The vapour barrier and under-layer must also be perfectly connected to each other.
  2. A fully waterproof vapour barrier
    The longitudinal and transversal coverings of the vapour barrier must be given a waterproof finish by the roofer.
  3. The vapour barrier adheres perfectly to the support
    A vapour barrier that adheres perfectly to the support is not only important when it comes to avoiding moisture problems. It is also important for wind resistance across the entire roof.

If the vapour barrier meets the above conditions, it is easy to choose the right one:

Interior climate Vapour barrier
Climate class I – III building 3 mm thick reinforced bituminous membrane
Climate class IV building Bituminous membrane covered or reinforced with an aluminium layer

An ALU-reinforced vapour barrier enables a building to stand the test of time

For this reason, a vapour barrier with additional aluminium protection is only strictly necessary for an interior climate class IV building. But it would certainly not be a bad idea to opt for an ALU-reinforced vapour barrier with additional protection for other buildings. At the moment, you may not know how the building will be used many years from now. For example, a dried fruit warehouse might later become a humid production hall. By opting for an ALU-reinforced vapour barrier, you can keep all options open for the building in the future.

As part of the IKO range, you can choose from five ALU-enhanced vapour barriers:

Self-adhesive vapour barriers (E4)
IKO shield ALU/SA 50m Cost-effective membrane for industrial roofs; low fire load
IKO shield PLUS ALU/SA 25m User-friendly membrane for application on steel and timber decks
IKO shield PRO ALU/SA 20m Robust and all-round membrane for heavier work
Vapour barriers for torch on applications (E4)
IKO shield ALU3 T/F User-friendly, suitable for short period temporary waterproofing
IKO shield ALU4 T/F Heavy duty, suitable for short period temporary waterproofing

Selecting the right vapour barrier

Would you prefer to opt for an aluminium-free vapour barrier? In this case, you should choose one that is sufficiently sturdy and will not yield. This is especially important when fitting a vapour barrier to a rough support or construction with interrupted surfaces.

All IKO vapour barriers that are self-adhesive or have a polyester reinforcement can always be used.

A few more tips

  • For renovation work, the existing bituminous waterproofing may act as a vapour barrier.
  • On interior climate class IV buildings, the vapour barrier cannot be perforated. Mechanical fasteners cannot be used.
  • Are you using insulation panels fitted with an aluminium layer? In this case, you must also fit a vapour barrier.

It is vital that you fit a vapour barrier on all flat roofs. Different moisture levels exist in every building and this can lead to unpleasant problems with dampness. Having a hermetically sealed vapour barrier fitted by a professional enables you to avoid a variety of problems.

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Do you know the difference between a warm, a cold and an inverted flat roof?

There are different types of flat roofs. The roof construction determines whether the roof is referred to as a warm, a cold or an inverted roof. The main difference is the location where the insulation is installed with respect to the roof construction and the roof covering. This has a significant impact on the lifespan of the roof. In this article, you can read about the difference and the pros and cons of each construction method.

Most new builds have a warm flat roof

Today, most new builds in Belgium have a warm flat roof. In this roof construction, the insulation is installed above the load-bearing structure, on the vapour barrier, and then the roof covering is placed on top of it.

Optimal protection of insulation and roof construction

A warm roof provides significant advantages for the lifespan of the roof. This is because both the insulation material and the entire roof construction are optimally protected from external influences. This makes the roof less sensitive to expansion and contraction, reducing the risk of tearing or bursting of the roof covering.

In a warm roof, the insulation material is protected on both sides:

  • The roof covering protects the insulation from rain, wind, and other weather conditions.
  • A vapour barrier protects the insulation from moisture from the inside of the building.

A warm roof construction guarantees that the roof will last a long time and also that its insulation value will remain optimal.

A cold roof has a number of major drawbacks

In a cold roof, the insulation is installed below or between the load-bearing beams, on top of which the roof covering is installed. This method of installing a flat roof has several drawbacks. That is why warm or inverted roofs are generally the preferred options.

A cold roof has two major disadvantages:

  1. The timberwork sits right up against the roof covering and is therefore insufficiently protected against temperature variations. This makes the entire roof construction much more liable to expansion and contraction, which may cause the roof covering to tear or burst.
  2. While it is possible to install a vapour barrier below the insulation, it remains particularly difficult to ensure adequate ventilation with this construction method. This makes cold roofs sensitive to condensation, which may cause the wooden roof construction to rot.

An inverted roof is sometimes a cost-effective option

An inverted roof is a warm roof that is installed upside down. Here, the insulation is placed over the roof covering. This roof construction is sometimes used for roof terraces and for flat roofs with heavy foot traffic. For refurbishments, this method may offer advantages over a warm roof.

Ballast layer required

In an inverted roof, the insulation is installed over the roof covering. Logically, this can only be achieved using insulation specifically designed for this purpose. This material must, for example, be highly pressure-resistant. This method always requires a ballast layer to be placed on top of the insulation. This layer may consist of gravel, tiles, stones, etc. and serves to protect the insulation from erosion as well as to keep everything in place.

Roof refurbishment without major rework

Inverted roof construction is particularly advantageous if you want to refurbish your roof or install extra insulation. An inverted roof can be a cost-effective solution, particularly when the existing roof covering is still in good condition. In fact, with an inverted roof, you do not need to replace the roof covering and you can simply install the insulation over the existing roof. It allows you to refurbish your roof without any extensive work.

Disadvantages of an inverted flat roof

An inverted roof also has a number of disadvantages. For example, the insulation layer should not project beyond the roof edge and the roof should be able to support the extra weight of the ballast layer.

Moreover, an inverted roof will lose more heat and you will therefore have to use more insulation to obtain the same performance. To avoid moisture issues, the roof must also have a greater pitch.

In most cases, a warm roof is the ideal method for installing a durable flat roof. This method adequately protects the entire construction from outside and inside moisture. An inverted roof may provide a solution in some cases, especially when refurbishing a flat roof or installing extra insulation.

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A utility roof helps you get the most out of your home or office

Do you have a home with a flat roof? In this case, you might have thought about converting it into a utility roof. This is a great idea as roof living spaces greatly increase the fun factor of your home or office building. What would you think, for example, of having a pleasant roof terrace where you can enjoy summer aperitifs or hold open-air meetings? Or how about a fragrant terrace garden bursting with colour where you can grow your own vegetables and herbs. Utility roofs have all kinds of possibilities. However, it is important to use an appropriate roof covering for this purpose. With IKO pantera or IKO carbon, you will be able to enjoy your utility roof for many years to come.

An utility roof with extremely resistant roofing

It goes without saying that a utility roof places an extra strain on the roof. It is important that the roof structure is sufficiently sound and suitable roofing materials have been used. However, you certainly should not delay your plans. Several excellent options exist when it comes to creating a highly comfortable or practical outdoor living space. With the appropriate roof covering, it is guaranteed that you can create a roof terrace or terrace garden that will bring you pleasure for many years. In addition, bituminous roof sheets will immediately give your roof living space an attractive and elegant look.

You can create a roof terrace or terrace garden as part of a renovation project or new construction. Check out our handy tool that will help you find the appropriate roof structure for your project.

Creating a roof terrace with IKO carbon or IKO pantera

At IKO, we have developed two families of roofing rolls, which are fully able to cope with the strain created by a roof terrace or garden terrace. The IKO carbon and IKO pantera ranges have a robust framework, which makes it possible to reinforce the membrane sufficiently so that the roof can cope with heavy use. These bituminous membranes are therefore the ideal choice for an utility roof.

The difference between Carbon and Pantera lies in the type of bitumen used. IKO carbon is made from plastomeric bitumen (APP), whereas IKO pantera is made from elastomeric bitumen (SBB). The IKO carbon range is finished on the lower side with the IKO TURBO profile with burls. This profile enables increased flame contact during flame welding, which makes it possible to lay the roll more quickly than a conventional roll with a smoother upper side.

The IKO carbon and IKO pantera families are able to resist flying sparks (Broof T4), which enables the membranes to show off their qualities, including under the most extreme test conditions. IKO membranes are made fire resistant by adding expandable graphite to the roofing roll.  This fire retardant effect remains stable throughout the life cycle of the roof.

The IKO carbon and IKO pantera ranges are finished with an attractive dark black granulate. This guarantees a very elegant and sleek finish. Another advantage of the mineral finish is that the upper layer is not subject to leaching and grey water can therefore be recovered without any problems.

Protecting your terrace garden roof against roots

Are you thinking of creating a terrace garden? In this case, you should go for a root resistance covering. This will make sure that plant roots cannot push through your roof covering. IKO carbon 250 and IKO pantera Roofgarden have a high quality roof resistant finish, which gives your roof additional protection.

IKO nv leefdak

A roof structure with an insurance-backed guarantee

Was your utility roof fitted by an IKO certified contractor? If it was, the roof comes with a COMPREHENSIVE 10-year insured guarantee. This guarantee covers the product, roof structure and work completed by the IKO Certified Contractor.  Yes, that’s right…!  With IKO pantera and IKO carbon, you will not be leaving anything to chance and will be able to sleep soundly in your roof living space. This is just what you need on a fine spring day. Make the most of it!

Would you like to receive more information about the IKO insured guarantee? Are you looking for an IKO certified contractor? Or would you like to become an IKO certified contractor yourself?

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