The point is that current materials & contruction practices--mostly the
almost-universal use of sheet goods (plywood, OSB, drywall,
etc.)--often results in houses that are quite tight, even when builders are
not particularly trying to build tight.
They then get the worst of both worlds--no control over ventilation in a
(relatively) tight envelope that is not tight enough provide comfort or low
energy bills.
If we want to go back to building "loose"--and some people do-- then go
back to 1 x 6 subfloors, 1 x 8 sheathing, beaded board walls & ceilings.
I've been in gorgeous houses built this way. But with this looseness
come substantial comfort and energy penalties, higher first costs, and no
guarantee that you will get good IAQ. This will depend on the weather,
prevailing breezes, and where the main holes are.
If, on the other hand, we're gonna use contemporary sheet goods, then it
makes sense to me to do it consciously, make it tight enough to get
comfort and low energy bills, and design in a ventilation system.
Typical construction practices today are already too tight to be loose,
but not tight enough to get the real advantages of being tight.
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