Brad Diepholz talks about “Attic Ventilation”-part 4
Brad Diepholz found the following information.
When it comes to moisture in the attic (this blog is continued from part 3) even vapor barriers for all their effectiveness cannot totally stop this process.
Another way moisture travels into an attic is by air moving through openings cut into a vapor barrier. These openings are commonly found at recessed ceiling boxes and attic entries.
The problems start when moist air hits cooler rafters, trusses and roof decking. The moisture condenses as water droplets or frost depending on what time of year it is. Eventually the condensation drips on the insulation below.
If too much water soaks into the insulation its volume can be compressed and its effectiveness will be reduced. The sequence of events that follows is very predictable.
Greater heat loss leads to colder rooms and colder rooms lead to a greater need for heat and greater use of the furnace leads to higher electrical bills. But that is only the immediate problem and its consequences.
As with heat buildup moisture buildup has long-term effects also. This is because not all condensing moisture drips into insulation. The structural elements of the house absorb some leading to wood rot and the deterioration of roofing materials.
Other moisture is likely to soak into the attic floor and eventually into ceiling material causing water stains and paint damage in the rooms below. Although the problems of attic heat and moisture have different causes they share a common solution.
A high-efficiency ventilation system that allows a uniform flow of air to sweep the underside of the roof sheating. In warmer months such a system exhausts hot air from an attic. In the colder months it exchanges warm moist air with cooler dry air.
In both cases the end result is the same. There will be less damage to the home.
The next blog (“Attic Ventilation”-part 5) I will talk about dealing with the effects of ice dams.
Typed by Brad Diepholz
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