EWI - does the thickness of board matter when it comes to thermal performed from a cost vs. Benefit?

Most of the cost of any job will be labour even if you're providing it yourself. Lower thermal value products won't be as coat effective as higher thermal value products.

Yes the thicker the better

It’s been proven that the thickness of the insulation boards has a major role on the efficiency of the system

The going start off point for the u value is 90 mm EPs boards ,you can use a 40 mm or 50 mm kingspan board which is more denser but has the same properties..but price will be a few hundred more for the denser boards on top for the job ..labour is the same ..hope that helps

Answering your question, the price is higher each time we increase the density of the product but the benefits are also greater when it comes to insulating. However, you can compensate if you do not use a board that is too thick by putting some material inside the walls of the house. of termination that also serves as insulation and would not have to be very thick, for example 27 or 35 millimeter plates of plaster and polystyrene