Connecting the Ventilation Fans

The ventilation fan connections also had to be done before the drywall can be installed. We have to ventilate the crawlspace to meet the requirements of a conditioned crawlspace. This can be done by placing a heating vent into the space or in our case by sucking heated and cooled air from the house through the crawlspace. Luckily the cubic feet per minute requirements are low. Just one cfm per 50 square feet of space. We have about 500 square feet of crawlspace so we have a 10 cfm ventilation fan that I installed in the master bedroom closet into the crawlspace below the hall.
The code requires the continuous vapor barrier as I installed and also a few options for conditioning the space. I am used the second one.

2004 Supplement To The IRC
IRC, Section R408.3, Unvented Crawl Space
b. Conditioned air supply sized to deliver at a rate equal to 1 cfm (0.47 L/s) for each 50 ft2 (4.7 m2) of under-floor area, including a return air pathway to the common area (such as a duct or transfer grille), and perimeter walls insulated in accordance with Section N1102.2.8,

Ducting for Crawlspace Ventilation Fan

Ducting for Crawlspace Ventilation Fan

The duct work attaches to the fan which ventilates to the hallway just behind the back door.

Closed Duct Outlet in Hall

Closed Duct Outlet in Hall

It is unobtrusive either open or closed.

Open Crawlspace Ventilation Fan

Open Crawlspace Ventilation Fan

There will be a cold air return vent near the stairs to allow the ventilation air to pull conditioned air into the crawlspace and vent it here at the rear of the hallway near the back door.

Inside the crawlspace the fan ductwork is capped by a plastic hood that draws in the air.

Hood for Fan inside Crawlspace

Hood for Fan inside Crawlspace

Unfortunately the fan is made for a 6″ to 8″ wall going straight through. I will have to box in the duct work but that is not such a problem since it will make it accessible in the future.

Duct for Ventilation Fan

Duct for Ventilation Fan

I also had to connect the bathroom shower fan’s duct. I had installed the fan and the duct through the wall several months ago but the duct was not connected. Now it is.

Bathroom Shower Fan Duct

Bathroom Shower Fan Duct

These were just two projects from the long list of items that need to be completed before drywall is installed.

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