Joe Lstiburek - Configurations of The Perfect Wall on Timber HP's Beyond R-Value

[@koenraadprincen7212]

Joe Lstiburek appearantly doesn"t trust the water repellent capabilities of TimberHP Board... a drainage gap behind the Timberboard is not needed.
_If you want to apply it - because it makes you sleep better - make sure it's air sealed but vapor open at the top or you will loose lots of the insulating properties of the Timberboard._
All those control layers behind the TimberBoard are not needed... tape or caullk the seams of the structural sheathing (plywood, OSB, gypsum, MDF, hardboard,...) and you have an air sealing ("air control layer"), with a "vapor throttle".
And use Timberboard at its full capabilities as a water control layer and insulation layer.
If you don't trust the Timberoard as your water control layer, apply a UV resistant vapor open housewrap at the outside (underneath the siding/cladding).

[@worganyos]

I don't think he said to put a drainage gap to the interior or the TimberHP

[@koenraadprincen7212]

@@worganyos You need to look at the drawing:
- On the outside of the TimberBoard the drawing mentions a "drainage cavity" (which is correct);
- On the inside of the TimberBoard the drawing mentions a "drainage gap" (which is to avoid to keep the thermal insulation of the TimberBoard useful).