20 common mistakes when installing windows

20 mistakes when installing windows — a review of typical fitting defects, from unfilled masonry joints to incorrect fixing and unprotected installation foam.

The material explains how installation errors affect airtightness, structural rigidity and the durability of the joint, and what exactly leads to cold bridging and complaints.

What the video shows

• Unfilled mortar joints and hollows in the opening: sealing materials have nothing to bond to, and water gets into the joint.


• The junction of window and balcony-door units needs separate sealing — not all coupling profiles include gaskets, otherwise the joint freezes.


• Fixing without prior marking out; corner zones are critical; fasteners must not resist thermal movement of the PVC.


• Too few fixing points: spacings should follow the scheme in the applicable standards (DSTU) or the profile maker's guidelines.


• The bottom profile must not be drilled through — moisture reaches the steel reinforcement; mounting on anchor plates is recommended.


• Couple the units and remove the protective film before setting them into the opening.


• Installation foam must be protected: a vapour barrier inside and waterproofing outside, otherwise the foam gets wet at the condensation zone and stops insulating.


• Form the tape corners correctly, allowing for the installation gap; PSUL expanding tape is fitted quickly, before it expands.


• A setting block under the middle of the balcony-door sill prevents sagging; setting blocks are covered with foam to avoid cold bridging.


• Foam joints are moistened for proper curing.