Roofs insulation with polyurethane systems

Polyurethane systems are a very efficient solution to insulate the buildings’ envelope, preventing unwanted air infiltrations. Polyurethane guarantees airtight insulation without extra components with 50% more efficiency than other insulating systems, which results in a saving of money and energy.

Regarding roofs insulation, whatever the type of cover the degree of impermeability must be independent of climatic factors and minimum insulation requirements must be met.


Paying special attention to singular points is key, since they are the most problematic areas: expansion joints, encounters with vertical walls, meetings with passing elements, anchoring of elements, gutters, sinks, corners, skylights, etc.

Flat covers

The hygrothermal insulation of flat roofs is essential to guarantee the comfort of the interior since, being a practically flat surface, it is necessary to collect the water to lead it to the drains. In addition, it is estimated that the energy losses of a building by the roof can be up to 30% of the total. That is why isolation plays such an important role.

According to the insulation arrangement we can distinguish between traditional covers, where the waterproofing system is installed on top of the thermal insulation, and inverted covers, where the thermal insulation is placed on top of the waterproofing coat.


The main threat affecting the envelops are leaks, whose consequences are often insidious as the symptoms may take time to manifest. To such an extent that, on many occasions, the cover is not operated until these leaks are detected in the lower houses, with the consequent degradation that this situation of deterioration has caused in an invisible during all that time.

That is why waterproofing the roofs is essential. Particular attention must be paid to the singular points and joints between walls, where almost all failures occur, for example: sinks, the edges of the walls or the joints in the pavement. In turn, the fact that the envelope is ventilated or not, influences on the choice of material depending on the existence or not of condensation.

Polyurethane offers important advantages such as resistance to ultraviolet radiation, elasticity or uniformity due to the absence of joints. Not only is it advantageous against weather conditions, but thanks its characteristics, polyurethane is also resistant to standing water. And finally, another advantage of polyurethane is that it can be walked on, allowing light pedestrian traffic.

Roof waterproofing with polyurethane Urespray F-75 - Download video


Design considerations

When renovating a roof with polyurethane we obtain a double advantage. On the one hand, the roof is reinforced mechanically by supplying the action of the anchors and, on the other hand, the thermal and / or acoustic insulation that it needs is provided.

  • It must not be installed on damp or rotten wood.
  • The roof must have ventilation openings at the height of the eaves to promote cross-flow of air. If the roof ventilation is insufficient due to building design restrictions, additional holes must be opened.
  • All the constructive elements involved in the process of renovation of the roof must be designed and built taking into account anti-humidity measures before the application of the product.
  • The product must not come into direct contact with smoke outlets, chimneys and other systems that produce heat.
  • This product forms a tough and resistant final system, a factor to be taken into account for future modifications.
  • Being that it’s made of polyurethane, this system designed to stabilize a roof can also improve its thermal transmittance.

Metal roofs

Metal roofs usually require renovation and waterproofing due to a multitude of factors, such as corrosion, high expansion and contraction over time (resulting in loosening of fastenings and cracks in joints and seals) or condensation and leaks in the waterproofing of difficult areas, in joints and unions (such as interior guttering, skylights, etc.).

After analyzing the type of roof, we also have to consider its situation: if it has been renovated, if it presents structural problems or if it does not have any type of thermal insulation.


BBA certification

The BBA certification has been granted to Synthesia UK range of polyurethane systems for roof insulation by The British Board of Agrément (BBA).This Agrément Certificate Product Sheet relates to the Synthesia range of spray-applied, in-situ insulation for flat and pitched roofs, including those with different coverings, of new and existing buildings.

The certification evaluates different key factors such as thermal behaviour, risk of condensation and durability.

Keymark certification

The Keymark certification is available for a wide range of products in the building sector, including thermal insulation materials.

It demonstrates compliance with European harmonised standards, in this case EN-14315-1, and it is recognised in EU Member States and accepted as equivalent to their own national certification marks (which are BBA and BSI in the United Kingdom).

Buyers of Keymark products benefit from the double guarantee offered by a system that, like the BBA mark, evaluates both the product and the manufacturer's production facilities.

The Keymark for thermal insulation products helps professionals and buyers to differentiate between products that comply with the minimum legal (safety) requirements in the European Economic Area in accordance with the requirements of the CE mark, and products that comply completely with the European Standards in force for such products.


Are you interested in roofs insulation? You can download the video of a roof waterproofing with polyurethane: 

Roof waterproofing with polyurethane Urespray F-75 - Download video



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