1. Lithoplast
  2. Waterproofing of buildings
  3. Green roof insulation

Green roof insulation

No simple roof tiles. On roofs of new homes, we more often see moss or carefully selected vegetation. And not only that. Terraces or even entire roofs are decorated with gardens with grown bushes and trees.

So-called green roofs have many advantages:

  • improve air in cities,
  • reduce overheating of roofs,
  • slow down rainwater drainage,
  • provide good heat-insulation,
  • and they look nice.

To select a particular type of waterproofing foil, you need to know what type of roof garden you plan to establish:


  1. Extensive green roof. This concept means a classic green roof made up of mosses and stonemasons. They do not need to be fertilized or watered.
  2. Simple intense green roof. Mosses are replaced by grasses and herbs on this kind of roof. Sometimes you have to mow the roof or water during the period of great drought.
  3. Extensive green roof Designation roof garden is suitable for this type of green roof where you can find trees and bushes. Caring for this garden is just as demanding as for a regular garden.


The particular selection of plants should be discussed with a garden architect. Do not rely on your own gardening experience. The plants on the roof have to face completely different conditions than those on the flower bed.


What to avoid


When designing a green roof, check the load bearing capacity of the roof structure including its individual layers. Do not forget to count the weight of the soil as well as the weight of the plants themselves. Vegetation created with stonecrops, grass, and herbs represents the load of approx. 15 kg/m²; in case of bushes the value is 20 kg/m²; in case of trees the load is 150 kg/m².


Utility loads and loads derived from weather conditions must be of course considered as well (snow etc.). In case of a small point loading capacity of the thermal insulation in roof structure, the bearing layer must be applied under the LITHOPLAST® DREN studded membrane.

Solutions for green roofs in practice

Select a suitable studded membrane according to the following table:

Forma vegetace Tloušťka vegetační vrstvy (mm) Hmotnost vegetační vrstvy (kg/m2) Vhodnost použití nopové fólie LITHOPLAST DREN
      20/1,0 40/1,5 60/1,6 80/2,0
mech - rozchodník 30 - 50 90 +++ + + +
rozchodník - mech - byliny 50 - 80 144 ++ ++ + +
rozchodník - byliny - tráva 80 - 120 216 ++ ++ + +
tráva - byliny 120 - 160 288 ++ ++ ++ +
Jednoduché intenzivní            
tráva - byliny 80 - 100 180 ++ +++ + +
divoké byliny - dřeviny 150 - 250 450 + ++ ++ +
trávník 100 a více 180 ++ ++ ++ +
nízké trvalky a dřeviny 120 - 150 270 ++ ++ ++ +
vyšší trvalky a dřeviny 150 - 200 360 ++ ++ ++ +
keřové výsadby 250 - 350 630 + ++ +++ ++
stromy 450 - 600 1080 + ++ ++ ++

Recommended structure of the green roof

  1. 1. The base of the green roof forms a balanced and coherent substructure of the supporting structure. It is important that there be no depressions, protrusions or other inequalities.

    2. This layer includes subbase iron-smoothed geotextile resistant against scrolling on anchoring screws. The subbase geotextile can be part of the insulating foil (IZOLTECH S 300).

    3. Waterproofing is the third layer whose details must be flawlessly made. FATRAFOL 808/2.3 or FATRAFOL 810/1.5 is the most suitable waterproof insulation for green roofs. PENEFOL 800/1.5 is a conditionally usable membrane for small structures; this membrane must be integrated and concealed in the structure.

    4. The LITHOPLAST® DREN 20/1.0 studded membrane is then placed on the surface. Fit the mounting joint with a one-sided adhesive butyl rubber band. If you use LITHOPLAST® DREN 40/ 1.5; LITHOPLAST® DREN 60/1.6 or LITHOPLAST® DREN 80/2.0 foils, place them at the joint and anchor them with a stapler.

    5. A plastic drainage element with small studs PetexDren 400 or PetexDren 900 with large studs must be placed on the studded membrane. Place the drainage foil on the joint. Use light gravel, such as kemzit to fill bigger studs to increase the bearing capacity.

    6. Further place the IZOLTECH K 300 filter geotextile with an overlap of 50 mm.

    7. If the vegetation layer on the roof is thick, lay the drainage from the lightweight aggregate to the kemrazite.

    8. The last layer is soil.