I have to replace my sealed unit in a door how can I calculate the thickness of the unit, as I wish to fit a solid panel with a cat door.

bogeynight, December 2012

Measure the thickness of the door itself.

Put a batten across the panel and measure the distance from the edge of the batten to the face of the panel.

Do the same again on the other side just in case there's a difference.

Do the maths...

A - (B + C) = X

Who said that Algebra was of no use to modern life?

Peccavi, December 2012

normally if its a old door its normally 24mm thick ifs its new then its likely to be 28mm thick. if u hold a ruler or tape measure right angle to the glass and u can normally see the thickness in the reflection as it will show it on the measurement. best to try it in low light. or if u are change the unit u will need to know how to remove it by removing the strips and just measuring the total thickness

kash, December 2012