PURboxes mounted in a prepared pocket in the masonry

14.3.2025 Ivan Landa

Are you not interested in a contact insulation system or do you intend to use it only to a limited extent? Do we have a solution for you to use PURbox for these cases as well?

In this article, we will present a practical solution - a "pocket" in the masonry that allows the installation of the PURbox.

If you prefer an alternative other than contact insulation, do not hesitate to try a building modification that will allow you to install a PURbox - even including insulation in the window area. Simply prepare a pocket in the masonry into which the box can easily fit.

A) Installation of boxes without contact insulation

Below are examples of box installation solutions for the two most commonly used building systems without contact insulation. The first one is the Ytong Lambda YQ thermal insulation block and the second one is brickwork with a thickness of 440 or 500 mm.

Ytong Lambda YQ
Preparation during implementation Status after installation of PURbox with PIR insulation

2. Brickwork 440 or 500 mm

Preparation during implementation Status after installation of PURbox with PIR insulation

B) Limited contact insulation

If you are planning contact insulation only to a limited extent, here is one possible case:

PIR insulation of the box in contact with the lintel and the window frame 30 (PBI30), 40 (PBI40), 50(PBI50), 60 (PBI60) mm. The thickness of the PIR insulation (30-60) will be selected according to the possibilities allowed by the whole composition with the contact insulation system.

Insulation of the window frame and connecting joints

It is necessary to think about the insulation of the lintel and the window frame - this is the weakest point of this detail. We therefore recommend using a PURbox type PBI with PIR insulation when installing into a prepared pocket. With this box you will insulate the critical detail and, most importantly, create more favourable conditions for the window - thanks to this you will get better thermal properties of the building and avoid thermal bridges. Proper installation and execution of the detail will easily stand up to all aspects.

For how high windows is this solution applicable, how should I choose?

You can see more details in our tables.

In the following tables you will see the minimum box depths in mm with regard to the type of blind and the insulation used.

PIR insulation for PBI