Research results: insulation | the roof
- Commissie Duurzaam
- 29 jan
- 4 minuten om te lezen
Bijgewerkt op: 9 feb
Table of contents of insulation
The roof - the current situation
Construction of the Kleiburg building roof
The flat roof of our building consists of:
the concrete floor with reinforcement;
an insulation layer of 100 mm (possibly replaced in 2013);
2-layer bitumen;
A gravel layer of approximately 5 to 7 cm.
With an Rc value of 2.958 m²/Kw, the roof covering meets the renovation requirements, but is below the current new construction requirements (6.3 m²/Kw).
What does this mean in concrete terms?
Homes built from 2000 onwards generally already have a reasonable insulation value, which means that the effect of additional insulation measures is more limited than in older homes (see also insulation - introduction ).
In the year 2000, the mandatory minimum Rc value for roof insulation in new-build homes in the Netherlands was 2.5 m²K/W .
The current renovation standard is therefore the same as the requirement that applied to new construction in 2000.
Opportunities for improvement
The HU students gave 3 options, Steeds Advies gave 1 option:
(HU) Option 1: Warm roof + inverted roof;
(HU) Option 2: Warm roof;
(HU) Option 3: Warm roof + inverted roof with sedum;
and (Always) Option 4: as option 2, but with a different thickness of insulation material.
Option 1. (HU) Warm roof + inverted roof
The existing roof already has an insulation layer and can be provided with an additional insulation layer. This layer is applied on top of the existing insulation and
Provided with the existing gravel layer. Because the current roof edge is too low, it must be replaced with a higher raised roof edge. This brings the Rc value to 5.889 m²k/w
Option 2. (HU) Warm roof
Another option is to remove the old insulation layer and replace it with a new, improved version (warm roof construction). By installing 220 mm PIR insulation, an Rc value of 5.918 m²/kW can be achieved. As with option 1, this also requires modifications to the roof edge.
Option 3. (HU) Warm roof + inverted roof with sedum
A third option is to leave the old insulation layer in place and apply an additional layer of insulation on top, as in option 1, and then cover it with sedum where possible. This also requires modifications to the roof edge, as with options 1 and 2.
Sedum won't increase the Rc value, but it will provide additional cooling in the summer. The sedum on the roof does require maintenance several times a year.
Option 4. (Always) As option 2, but with a different thickness of insulation material
The warm roof as described in option 2, but with high-quality, 140 mm thick, hard-pressed PIR insulation as insulation material. This high-quality, pressed PIR is thinner because it has a higher insulation value.
It still needs to be investigated whether the roof edge needs to be adjusted with this variant.
Costs, subsidy and National Heat Fund
The roof area of Kleiburg phase 1 is measured differently in various reports, namely approximately 962 m², 860 m², and 754 m². Accurate surface area measurement is important not only for the cost of the improvement but also because the subsidy is provided per m².
The reports only provide a cost estimate (2024 price level) for options 2 and 4. This is only a rough estimate, as the final price depends on the chosen option and the insulation materials used.
The cost estimates differ:
€96,122 for a surface area of 860m2 with option 2;
and €211,411 for a surface area of 754m2 with option 4.
Subsidies for energy-saving measures, including roof insulation, can be applied for through the SVVE (Homeowners' Association). The condition is that the new insulation material has a minimum thermal resistance of 3.5 m²K/W .
This means that option 1 is not eligible for subsidy.
The subsidy amounts to:
for one insulation measure: €16.25 per m2;
for two or more insulation measures: €32.50 per m2;
for the smallest surface area this amounts to 754 x € 16.25 = € 12,252 or 754 x € 32.50 = € 24,505.
The roof insulation can be further financed by a loan from the National Heat Fund.
Read all about saving, borrowing and subsidies here.
Marginal note
(Protected cityscape) In the first three options, the current roof edge is too low and will have to be replaced with a higher, raised roof edge. The building's aesthetic committee may only grant permission for this if it is also done for the other three phases. Whether the roof edge must also be raised for option 4 still needs to be investigated.
Want to read more about insulation?
Do you have any questions, ideas or would you like to share your experiences?
Email us at duurzaamkleiburg1@gmail.com . Together we'll chart a path toward a future-proof Kleiburg.