Airbrick position with ducting tube

[AMZO]

Hello all,

I need some help and advice:

A building control officer has recommended a builder to use 6" high timber frame joists to be used with 100mm insulation inside the frame as the proposed suspended timber frame joist of 4" high isn't strong enough for the underfloor heating, because of the span. The remaining 50mm are enough for housing the underfloor heating.

Then, the other amendments regarding the construction is that weep holes are unacceptable as need to be replaced with airbricks. If we are going to use airbricks in the extension - does this mean we need to create 150mm void cross ventilation for a timber suspended flooring or does this need an airbrick ducting tube to run across either within the insulation with timber joists to within the new layer of cement to be connected to the existing wall? The idea was not to have 150mm air void because its too high in terms of levelling with the existing dwelling.

This is because the builder's sketch shows that the airbrick is supposed to be located in front of the wall but connects to the insulation and timber frame joists and I don't know if this is correct for not because the sketch is not featured in the NBHC guideline. But the builder has stated that the builder control officer has recommended to do this.

I added an architects detailed drawing interpretation to see if this is correct or not because he was confused with the builders sketch.

Any thoughts would be useful.

 

[RandomGrinch]

I am no expert, so please feel free to ignore!
If I understand correctly, your architect has specified a ducting tube to allow ventilation from an air brick on the extension, presumably to an air brick on your existing house to allow cross ventilation of your existing floor.
Whereas your builder (and possibly building control) have specified the air bricks ventilate the bottom of the joists in your new floor as well as cross ventilation to your existing.
I suspect your builder maybe correct! However, you need the builder and architect (and building control!) to talk to each other!
Nothing useful will be achieved by chinese whispers. The builders will end up building it the way they believe to be correct.
You may also have more luck in getting opinions, if this was posted in the 'Building' forum, rather than the 'Your Projects' section.
Good luck

...and you will still need weep holes to drain the cavities!