Ventilation issue, help!

[fusion98]

If the vent for an enclosed space (flat roof with 19cm gap between chipboard and plasterboard) is on a back wall and the joists run left to right & i need air circulation above the insulation, do i drill through the joists above the insulation line? if so would 15mm do and how many holes would you drill for a 7 foot width? Currently the vent is below the joists which is useless for insulation purposes.
thanks


1) i cant remove the roof, too costly
2) the room is freezing due to no insulation, and you can hear everything outside
3) any other idea of ventilation is welcome

 

[^woody^]

No amount of drilling joists will ventilate a flat roof, unless you take the Swiss cheese approach - which does not bode well for the structural integrity of the joists

If you have, or can take the ceiling down, then just fill the whole space between the joists with your chosen insulation and make sure its tight up against the roof deck