ᐅ Where to install ducts for controlled residential ventilation in the ceiling of the top floor

Created on: 24 Feb 2016 19:21
W
world-e
Hello,

can someone briefly explain where the ducts for a mechanical ventilation system with heat recovery can be installed on the upper floor if the house has two full stories, the top ceiling is a beam ceiling, and the roof above is either uninsulated or has only 60mm (2.4 inches) of insulation above the roof deck? If the ducts are installed above the beam ceiling, they are outside the thermal envelope; if installed within the insulation, much of the insulation’s effectiveness is lost. Also, running ducts perpendicular to the beams is difficult. How is this usually done? Thank you.
S
Sebastian79
25 Feb 2016 22:12
That is a different starting point with the vapor retarder in your attic space – that’s why I asked about it. In that case, ventilation through a mechanical ventilation system with heat recovery is even mandatory.
S
Saruss
25 Feb 2016 22:42
Sure. But I wouldn’t rely on “random” air exchange—either be bold and leave a “gap” or use a controlled ventilation system at a low setting.
S
Sebastian79
26 Feb 2016 05:49
I don’t rely on that, but measure there.

Although I’m still not sure whether I should just ventilate there, or only extract air, or do both in case of need.
V
Vitalio
27 Feb 2016 11:43
2 full stories, installation space of 15cm (6 inches) between the vapor barrier and substructure

Unplastered ceiling with steel frame, OSB panels, pipes and cables, window on the right.