Frequently asked questions

Cavity wall insulation ensures that heat escapes less quickly through the cavity and the masonry. Your home stays warmer in winter and cooler in summer, resulting in lower energy costs and increased living comfort. In addition, a well-insulated cavity helps prevent moisture problems and often increases the value of the property. The investment is relatively low and usually pays for itself within a few years (especially when you make use of subsidies).

Our qualified installation team performs a careful inspection of the cavity walls to assess their suitability for insulation. Small holes are then drilled at strategic locations in the exterior wall, allowing the insulation material to be blown or injected into the cavity. After installation, the holes are neatly sealed with mortar that matches the existing joint color, ensuring minimal impact on the appearance of your home.

The duration of the installation depends on the size of your home and the accessibility of the cavity walls. In most cases, the installation process can be completed within one day. Work is carried out only on the exterior, so you will experience no disruption indoors. The drilling and filling process also produces minimal noise and very little mess. After completion, our team will of course clean everything up, and your facade will look neat again.

Yes, through the ISDE subsidy (national scheme), you can receive a reimbursement per square meter of cavity wall insulation. If you choose two measures (for example cavity wall insulation combined with floor insulation), the subsidy amount is doubled and the payback period decreases. In addition, some municipalities offer extra schemes or local subsidies. These arrangements vary by region; on our service area page you can see which subsidy is available for your home. We also assist and advise you on the available subsidies so you can get the most out of them.

The payback period for cavity wall insulation varies depending on your specific situation, such as the type of insulation material used and your current energy consumption. On average, the payback period is between 3 and 5 years due to savings on energy bills. Our team can provide a tailored calculation to give you an accurate estimate of the payback period for your home. You can also calculate this yourself using our calculator!

Some people believe that there must be air in the cavity to prevent moisture from penetrating indoors and to allow moisture in the cavity to be removed through ventilation. That is not entirely correct. If cavity wall insulation is properly installed, no moisture from outside will penetrate through the cavity that is fully filled with insulation material. Ventilation of the cavity is also not necessary, as it contributes very little to drying the masonry. This does, however, only apply if the masonry is in good condition and not susceptible to frost. Our specialist will assess this during the inspection.

Crawl space insulation is a way to insulate the crawl space of your home. Insulation material (such as EPS HR++ beads or insulation chips) is applied to the ground of the crawl space. The material forms an insulating layer that blocks cold air from the crawl space and reduces moisture. As a result, the floor feels warmer and your home loses less energy. Crawl space insulation is installed from below and does not require any renovation of your floor. It is a quick solution and suitable for crawl spaces where floor insulation is not possible, for example when the crawl space is lower than 50 cm.

Crawl space insulation is particularly suitable for homes with a low crawl space, a damp crawl space, or when the underside of the floor is difficult to access. Your crawl space must be at least 35 centimeters high to properly apply the insulation material. This method is ideal when: floor insulation from the underside is not possible, the crawl space feels cold, damp, or wet, you experience drafts or cold floors, or when pipes or obstacles are in the way.

Crawl space insulation offers several advantages, including:

• Increased living comfort due to warmer floors and reduced drafts.
• Reduction of moisture problems, contributing to a healthier indoor climate.
• Energy savings through better heat retention, leading to lower heating costs.
• Simple installation without major renovations.
• It contributes to an increase in property value, as your energy label improves.

The installation of crawl space insulation is relatively quick and can usually be completed within one day. The exact duration depends on the size of the crawl space and its accessibility. The process requires minimal preparation and no major renovations, making it a fast and effective way to insulate your home.

Yes, through the ISDE subsidy (national scheme), you can receive a reimbursement per square meter of crawl space insulation (the amount is €3.00/m²). If you choose two measures (for example cavity wall insulation combined with floor insulation), the subsidy amount is doubled. In addition, some municipalities offer extra schemes or local subsidies. These arrangements vary by region; on our service area page you can see which subsidy is available for your home. We also assist and advise you on the available subsidies so you can get the most out of them.

What is the difference between crawl space insulation and floor insulation?
The main difference lies in where the insulation material is applied:

• Floor insulation is installed on the underside of the floor and provides a higher insulation value.
• Crawl space insulation is applied to the ground of the crawl space and mainly works by blocking cold air and moisture.

Crawl space insulation is ideal when the crawl space is too low for floor insulation or when pipes, beams, or other obstacles make floor insulation impossible. Floor insulation requires a minimum height of 50 cm, while crawl space insulation requires a minimum height of 35 cm. Our advisor will be happy to tell you more about this!

Various materials can be used for floor insulation, including PIF insulation foil, EPS beads, and insulation chips. The choice of material depends on the specific situation, such as the available space, the condition of the floor, and your personal preferences regarding sustainability and insulation performance. Our specialist will be happy to advise you on this!

Floor insulation can be installed in different ways, depending on the type of floor and the chosen insulation material. For a wooden floor, the material is often placed between the floor joists, while for a concrete floor the insulation material is sprayed or attached to the underside of the floor. The work can usually be carried out from the crawl space, which minimizes the impact on your home and daily life.

The benefits of floor insulation include:

• Increased living comfort by eliminating cold drafts and creating warmer floors.
• Energy savings due to reduced heat loss, leading to lower heating costs.
• Reduction of moisture problems in the home, contributing to a healthier indoor climate.
• Potential increase in the value of your home due to an improved energy label.

Most homes with an accessible crawl space are suitable for floor insulation, provided that the crawl space meets the following requirements:

• The crawl space is at least 50 cm high.
• The space is dry enough and safe to work in.
• The underside of the floor is easily accessible.
• There are no pipes or obstacles in the way.

If you’re thinking that this doesn’t fully apply to your situation, then crawl space insulation is a good alternative. It is also effective and helps prevent heat loss from the crawl space.

However, our advisor will always assess during an appointment which type of insulation best suits your home, ensuring you get the highest insulation performance and optimal comfort.

Roof insulation is one of the most effective ways to save energy and make your home more comfortable. A large portion of heat in a home is lost through the roof; without proper insulation, this can be as much as 30% of total heat loss. By insulating the roof, heat stays inside much better during winter, while your home remains cooler in summer. As a result, your heating system doesn’t have to work as hard, leading to lower energy consumption and noticeable savings on your energy bills.

A well-insulated roof also ensures a more consistent indoor temperature and helps prevent drafts and cold spots. Another advantage is that roof insulation contributes to an improved energy label, which is beneficial for the value of your home. And thanks to available subsidies, the payback period is often shorter than you might expect.

We offer various insulation solutions suitable for both flat and pitched roofs, including PIF insulation foil, Supafil Cavity 033 blowing wool, and Gramitherm. Depending on the structural characteristics of your roof and your personal preferences, our experts can advise you on the most suitable materials and methods for your specific situation.

The installation time for roof insulation can vary depending on the type of roof and the size of the project. In general, insulating an average roof can be completed within a few days. Our team works efficiently and professionally to minimize any disruption for you as a resident.

Yes, through the ISDE subsidy (national scheme), you can receive a reimbursement per square meter of roof insulation (the amount is €16.25/m²). If you choose two measures (for example roof insulation combined with floor insulation), the subsidy amount is doubled. In addition, some municipalities offer extra schemes or local subsidies. These arrangements vary by region; on our service area page you can see which subsidy is available for your home. We also assist and advise you on the available subsidies so you can get the most out of them.

The cost of roof insulation varies per home and is determined by factors such as:

• The type of roof (flat or pitched)
• The surface area
• The accessibility of the roof
• The desired insulation value
• The chosen insulation material
• Whether the insulation is applied from the inside or the outside

For this reason, we cannot provide a fixed price without first assessing your roof. During a no-obligation inspection, we measure the roof, assess the structure, and immediately calculate the exact costs for your situation. You will receive a clear, tailored quotation right away.

Yes, in most cases you can receive a subsidy for insulating your home. The main scheme is the national ISDE subsidy, which provides a reimbursement for measures such as cavity wall insulation, floor insulation, roof insulation, and crawl space insulation. The amount of the subsidy depends on the number of square meters and the number of measures you carry out. If you implement two or more measures within twelve months, the subsidy amount per m² is even doubled.

In addition, many municipalities offer local subsidies or additional schemes. These can vary by municipality and range from small contributions to full additional reimbursements. Because this is determined locally, you can check on our service area page which schemes apply in your municipality and whether you are eligible.

In many cases, subsidies can be combined, making insulation even more affordable.

For the ISDE subsidy, the conditions are set nationally. The most important requirements are that you are both the owner and occupant of the home, that the house was built before 2019, and that the insulation is carried out by a certified insulation company. In addition, the materials used must meet strict technical requirements, such as minimum Rd values and recognized quality certifications. You must also apply for the subsidy within twelve months after completion, and you will need photos, invoices, and m² data as proof (we provide these).

For municipal subsidies, the conditions can vary significantly by municipality. Some municipalities apply income thresholds, others require specific materials or combine subsidies with energy advice. It is therefore advisable to always check the conditions applicable in your municipality; you can easily find this on our location pages.

To qualify for the ISDE subsidy, insulation materials must meet minimum insulation values. The RVO assesses this based on the Rd value (for insulation materials) and the U value (for glass). The higher the Rd value, the better the material retains heat. For glass, it is the opposite: the lower the U value, the less heat loss. We only use insulation materials that meet these requirements so you can get the most out of your subsidy.

Each insulation measure has specific requirements:

In addition to the insulation values, a minimum number of square meters must also be insulated in order to qualify for a subsidy. These minimum surface areas vary depending on the type of property (detached house, corner house, terraced house, apartment).

Want to be sure your home meets the requirements? We’re happy to check this for you free of charge and immediately advise you on the best subsidy combination.

You always apply for the ISDE subsidy after the insulation has been completed. To do this, you log in to the RVO using DigiD, enter the technical details of the completed measure, and upload your invoices, proof of payment, and photos. Since the RVO has specific guidelines for supporting documents, it is important that all documentation is complete and submitted according to the requirements. At De Vries Isolatietechniek, we ensure that you receive all the required documents and can guide you through the application process so you can be confident that everything is submitted correctly.

For municipal subsidies, the application process often works differently. Some municipalities allow you to arrange this together with the national subsidy, while others use separate forms or conditions. The exact procedure therefore depends on your municipality, which you can check via our service area page or on your municipality’s website.

The exact subsidy you receive for insulation depends on the type of measure you carry out, the number of square meters insulated, and whether you combine one or two (or more) measures. The ISDE subsidy works with fixed amounts per square meter: if you choose one measure, you receive a fixed amount per m², but if you combine two or more measures, the amount per m² is doubled.

In addition, in 2025 there is an extra bonus for biobased insulation materials, which is added on top of the standard ISDE amounts.

The final subsidy therefore varies per situation, but the overview below gives you an indication of the subsidy amounts per m² applicable in 2025:

Regarding local subsidies, the amounts vary by municipality and are regularly updated. You can check the exact amounts via our service area page or on your municipality’s website.