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Calculate material requirements for sealing windows and doors

30% of all air leakage comes through windows and doors. Proper sealing prevents this. An effectively sealed connection between the window/door and the wall can drastically reduce energy usage.

Secondary Sealing with Flexseal-T

Always start with a secondary seal at the bottom of the installation opening (window/door opening) regardless of the chosen method. The secondary seal consists of the flexible and elastic sealing tape Flexseal-T.

When you enter the width of your windows or doors and the quantity, we calculate how much material you need below in Method A, B, and C.

Assembly instructions can be found here

Method A - Expanding Drive Belt

In Method A, self-expanding drive belts are used T-Expand Standard or T-Expand Pro.

Enter the width and height of your windows or doors and the quantity, and we will calculate how much material you need.

Assembly instructions
T-Expand Standard
T-Expand Pro










You need:


Method B - Mineral wool caulking with diffusion-tight tape inside and diffusion-open tape outside

Method B is used for external taping Airtight-T and for internal taping use T-Flex.
For caulking, you traditionally use caulking tape made of mineral wool.

Enter the width and height of your windows or doors and the quantity, and we will calculate how much material you need.

Assembly instructions
Airtight-T
T-Flex










You need:


Method C - Mineral wool caulking with diffusion-tight tape inside and outside

Method C is used for external taping T-Flex Outdoor and for internal taping use T-Flex. For caulking, you traditionally use mineral wool caulking strips.

Enter the width and height of your windows or doors and the quantity, and we will calculate how much material you need.

Assembly instructions
T-Flex Outdoor
T-Flex