nebbian, water begins to expand only at boiling point. It does not "push" before that.
And under pressure, water boils at higher temperatures anyways... for water trapped in a board at 15psi, you would need to heat the board at 200C (your board will be destroyed before that) before the water has any impact on delamination...
Make the experiment: heat a pan full of water with a tight lid: there will be pressure on the lid only at 100C, not before.
www.engineeringtoolbox.com/boiling-point-water-d_926.html
PS: There are a lot counter-intuitive facts on air & water: for instance, humid air is actually lighter than dry air...
