From July 1, 2025, the Flemish government requires all companies with a high electricity consumption (> 1000 MWh) to install solar panels on at least 10% of their total roof area That area will gradually increase to 15% in 2030 and 20% in 2035. Before you rush headlong into installing a PV system on your roof, there are a few points to consider. We always recommend a thorough inspection and renovation may be necessary to enjoy this green investment for years to come.
Compliance with this new obligation requires a thoughtful approach. "It is not acceptable to ask a PV installer to install the panels on an existing roof without first taking a thorough look at the roof and its supporting structure," warns Steven De Gryse, account manager at Tectum Group. "The basic assumption is that a roof should still be in good enough condition to support solar panels for 25 years without any problems. It therefore makes sense to work with an experienced roofer to inspect the roof and check whether the waterproofing is still in good condition and whether the insulation is suitable for placing additional weight on it."
The existing insulation must have sufficient compressive strength and must not collapse when you walk on the roof. "When that compressive strength is not adapted to the additional load of PV panels, there are two options: either we replace the insulation package with an insulation with adapted compressive strength, or we place an additional insulation layer on top of the existing insulation. In the latter case, there are some concerns. One rule of thumb is that the R-value of the new insulation must be 1.5 times that of the existing insulation to prevent internal condensation. This is detrimental to the insulation value. A further condensation calculation can provide information about this. In addition, the building structure must be able to support the extra weight. In some cases it is necessary for a structural engineer to investigate this," Steven De Gryse explains.
If the intention is to retain the existing roof insulation, it is a good idea to inform the roofer openly and fully about any problems with the roof. "A minor leak, for example, can already have a major impact on the insulation. With a targeted destructive examination, we can visualize that impact. If, after an incision, it appears that the insulation is wet, we can look at replacing some or all of the insulation. We always think along according to the budget."
When the insulation is retained, but it makes sense to additionally insulate from an energy perspective, the insulation package can often simply be applied to the existing roof waterproofing. "In the case of plastic waterproofing, it is important to make the membrane stress-free by making incisions at the corners with the roof upstand, or remove them completely. It offers the advantage that you can save on costs for demolition and disposal of the material" said Steven De Gryse.
Additional insulation on top of the existing roof structure may run into the limits of the roof curb. "In such cases, raising the roof curb may be an option. In 80% of the cases we can solve this with a wooden frame of 10 to 30 cm. In doing so, we also provide an appropriate finish on the facade side.
It is important to have a clear warranty responsibility between the roofer and the PV installer. From this point of view, it is appropriate to deliver the roof after the renovation, possibly after a waterproofing test, and only then release it to the installer of the solar panels. "We always recommend applying a rubber mat between the ballast of the solar panels and the roof waterproofing. That helps distribute the pressure better and absorb any movement of the solar panels. We can also provide anchors in the roof seal during the roof renovation to mount the panels on. This way, we contain any damage caused by movement of the installation. For any penetrations, the roofer comes back during the installation of the PV panels to work out a correct, watertight solution."
Before the roofer's visit, it makes sense to check with the company insurer to see if it has any particular requirements for the roof waterproofing or structure with regard to the installation of PV panels. For example, some insurers expect a fire-resistant layer.
The vision of a stability engineer is also valuable to start from the correct information immediately when working out a solution. This saves a lot of time and unpleasant surprises.
The requirement for PV panels applies to large consumers. These are usually large companies with operations that cannot be easily interrupted. "Tectum Group has experience working in the most challenging business environments, such as petrochemicals, pharmaceuticals or manufacturing companies. We have previously performed roof renovations for Air Liquide, Boflex and Lamifil with a view to installing a PV system. Furthermore, we are currently working for Orbix, Graco and Safran. In these cases, we review with the client what is necessary to carry out our work without impacting business operations. That may mean adjusting our schedule to a period of downtime, for example, during a leave of absence. In other cases, we work out specific solutions to work without disturbing the company. This can be by taking measures to avoid dust nuisance or to avoid logistical hindrance due to interaction," Steven De Gryse says.
Safety is priority number one when working on the roof. "During preparation, we study what personal and collective protective equipment is possible and necessary to work safely. We also have VCA** and VCA-P accreditation to work in the most demanding sectors.
We also think along with our clients when it comes to sustainability obligations. For example, we provide a waste management plan tailored to each project and meticulously record the disposal of the various material streams. We provide this information and waste certificates to the client. In short, we stand for completely unburdening our clients," concludes Steven De Gryse.
Do you have plans to renovate the flat roof of your industrial buildings? Contact Steven De Gryse, industry account manager, for advice or a no-obligation quote.
steven.degryse@tectumgroup.be | +32 470 95 16 57
From July 1, 2025, the Flemish government requires all companies with a high electricity consumption (> 1000 MWh) to install solar panels on at least 10% of their total roof area That area will gradually increase to 15% in 2030 and 20% in 2035. Before you rush headlong into installing a PV system on your roof, there are a few points to consider. We always recommend a thorough inspection and renovation may be necessary to enjoy this green investment for years to come.
Compliance with this new obligation requires a thoughtful approach. "It is not acceptable to ask a PV installer to install the panels on an existing roof without first taking a thorough look at the roof and its supporting structure," warns Steven De Gryse, account manager at Tectum Group. "The basic assumption is that a roof should still be in good enough condition to support solar panels for 25 years without any problems. It therefore makes sense to work with an experienced roofer to inspect the roof and check whether the waterproofing is still in good condition and whether the insulation is suitable for placing additional weight on it."
The existing insulation must have sufficient compressive strength and must not collapse when you walk on the roof. "When that compressive strength is not adapted to the additional load of PV panels, there are two options: either we replace the insulation package with an insulation with adapted compressive strength, or we place an additional insulation layer on top of the existing insulation. In the latter case, there are some concerns. One rule of thumb is that the R-value of the new insulation must be 1.5 times that of the existing insulation to prevent internal condensation. This is detrimental to the insulation value. A further condensation calculation can provide information about this. In addition, the building structure must be able to support the extra weight. In some cases it is necessary for a structural engineer to investigate this," Steven De Gryse explains.
If the intention is to retain the existing roof insulation, it is a good idea to inform the roofer openly and fully about any problems with the roof. "A minor leak, for example, can already have a major impact on the insulation. With a targeted destructive examination, we can visualize that impact. If, after an incision, it appears that the insulation is wet, we can look at replacing some or all of the insulation. We always think along according to the budget."
When the insulation is retained, but it makes sense to additionally insulate from an energy perspective, the insulation package can often simply be applied to the existing roof waterproofing. "In the case of plastic waterproofing, it is important to make the membrane stress-free by making incisions at the corners with the roof upstand, or remove them completely. It offers the advantage that you can save on costs for demolition and disposal of the material" said Steven De Gryse.
Additional insulation on top of the existing roof structure may run into the limits of the roof curb. "In such cases, raising the roof curb may be an option. In 80% of the cases we can solve this with a wooden frame of 10 to 30 cm. In doing so, we also provide an appropriate finish on the facade side.
It is important to have a clear warranty responsibility between the roofer and the PV installer. From this point of view, it is appropriate to deliver the roof after the renovation, possibly after a waterproofing test, and only then release it to the installer of the solar panels. "We always recommend applying a rubber mat between the ballast of the solar panels and the roof waterproofing. That helps distribute the pressure better and absorb any movement of the solar panels. We can also provide anchors in the roof seal during the roof renovation to mount the panels on. This way, we contain any damage caused by movement of the installation. For any penetrations, the roofer comes back during the installation of the PV panels to work out a correct, watertight solution."
Before the roofer's visit, it makes sense to check with the company insurer to see if it has any particular requirements for the roof waterproofing or structure with regard to the installation of PV panels. For example, some insurers expect a fire-resistant layer.
The vision of a stability engineer is also valuable to start from the correct information immediately when working out a solution. This saves a lot of time and unpleasant surprises.
The requirement for PV panels applies to large consumers. These are usually large companies with operations that cannot be easily interrupted. "Tectum Group has experience working in the most challenging business environments, such as petrochemicals, pharmaceuticals or manufacturing companies. We have previously performed roof renovations for Air Liquide, Boflex and Lamifil with a view to installing a PV system. Furthermore, we are currently working for Orbix, Graco and Safran. In these cases, we review with the client what is necessary to carry out our work without impacting business operations. That may mean adjusting our schedule to a period of downtime, for example, during a leave of absence. In other cases, we work out specific solutions to work without disturbing the company. This can be by taking measures to avoid dust nuisance or to avoid logistical hindrance due to interaction," Steven De Gryse says.
Safety is priority number one when working on the roof. "During preparation, we study what personal and collective protective equipment is possible and necessary to work safely. We also have VCA** and VCA-P accreditation to work in the most demanding sectors.
We also think along with our clients when it comes to sustainability obligations. For example, we provide a waste management plan tailored to each project and meticulously record the disposal of the various material streams. We provide this information and waste certificates to the client. In short, we stand for completely unburdening our clients," concludes Steven De Gryse.
Do you have plans to renovate the flat roof of your industrial buildings? Contact Steven De Gryse, industry account manager, for advice or a no-obligation quote.
steven.degryse@tectumgroup.be | +32 470 95 16 57
From July 1, 2025, the Flemish government requires all companies with a high electricity consumption (> 1000 MWh) to install solar panels on at least 10% of their total roof area That area will gradually increase to 15% in 2030 and 20% in 2035. Before you rush headlong into installing a PV system on your roof, there are a few points to consider. We always recommend a thorough inspection and renovation may be necessary to enjoy this green investment for years to come.
Compliance with this new obligation requires a thoughtful approach. "It is not acceptable to ask a PV installer to install the panels on an existing roof without first taking a thorough look at the roof and its supporting structure," warns Steven De Gryse, account manager at Tectum Group. "The basic assumption is that a roof should still be in good enough condition to support solar panels for 25 years without any problems. It therefore makes sense to work with an experienced roofer to inspect the roof and check whether the waterproofing is still in good condition and whether the insulation is suitable for placing additional weight on it."
The existing insulation must have sufficient compressive strength and must not collapse when you walk on the roof. "When that compressive strength is not adapted to the additional load of PV panels, there are two options: either we replace the insulation package with an insulation with adapted compressive strength, or we place an additional insulation layer on top of the existing insulation. In the latter case, there are some concerns. One rule of thumb is that the R-value of the new insulation must be 1.5 times that of the existing insulation to prevent internal condensation. This is detrimental to the insulation value. A further condensation calculation can provide information about this. In addition, the building structure must be able to support the extra weight. In some cases it is necessary for a structural engineer to investigate this," Steven De Gryse explains.
If the intention is to retain the existing roof insulation, it is a good idea to inform the roofer openly and fully about any problems with the roof. "A minor leak, for example, can already have a major impact on the insulation. With a targeted destructive examination, we can visualize that impact. If, after an incision, it appears that the insulation is wet, we can look at replacing some or all of the insulation. We always think along according to the budget."
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