Floor timber joists and no ventilation

lokz

Hello all,

I am putting a new floor in my garage. There will be 4 * 2 joists over double layer of 1200 gauge DPM to make the floor sturdy and 75 mm of insulation in between them. T&G board over top of it and laminate flooring.

I understand the risk of timber rotting without ventilation, but how worried should i be. How bad will it be in say 5 , 10 or 20 years.

The bathroom space in the garage is already built that way. The building inspector said he will sign off but doesn't suggest it. in my bathroom i went that way because of the units which need more support. Now for the remaining space, I am not sure as this will be my office space and spare bed room.

All the 3 builders i spoke to suggested timber joists so that it will be more sturdy.

The other option for me is levelling screed to level about 5 mm of the garage space and floating floor on top of it.

Couple of pictures attached. Any advice appreciated.