I have a flat roof home with 3 feet of clearance from attic floor to ceiling. It is 1920 square feet, existing home. The space is unvented, and has one access hatch. It is in the master bedroom closet with no close access to a window or door. We plan to spray foam the roof deck. I am struggling to figure out how to ventilate the space during the job without positively pressurizing the attic. The home is stucco, so we do not have an easy way to create a hole to the outside. I typically rent a manhole fan. We can't suck air out of the hatch since overspray would ruin the rented fan (I think, maybe not?) When it is gables, I just leave the gable vents open(or mushrooms) until the very end of the job, and have the fan blow up into the attic hatch and out the gable ends. How do you spray foam guys ventilate an unvented attic space while spraying? We have just started on retrofit market, so most of our jobs have been new homes without these problems.

Views: 310

Reply to This

Replies to This Discussion

Hi Craig,

No direct experience in what you asked, but I have seen the venting process used for asbestos abatement.  In your case, an exhaust fan pulling through a large flex duct down through that hatch and extended as far as necessary.  I have a window fan that roars and I have used it to enhance an IR inspection when the blower door was not part of the consultation.  So even if the fan got contaminated, they aren't that expensive.  A round duct through a square hatch should leave plenty of room for fresh air.  Just thinking out load, good luck.

Bud

Bud - I think that is what we decided, except I will seal the exhaust fan in tight in the hatch, run a 20" flex duct to the outside. Keep a window open and allow the recessed cans to let air into the attic. If that isn't enough air we can always open a supply duct since the attic will be depressurized. Came down to finding the right combo of fan and duct. Can get both for around $100 total. I think the fans will hold up even with some overspray.

There are paper hoods that hook to your compressor hose.  Very slick and inexpensive.  Much better than counting on face masks. 

RSS

Videos

  • Add Videos
  • View All

Twitter

Latest Activity

Jeffrey Anthony posted a discussion

9 Blower Door Frames, 9 Shrouds, and 11 Fans, and 8 Fan Controllers For Sale

We are clearing out some of our redundant inventory. All items are from The Energy Conservatory.9…See More
1 hour ago
Quinn Korzeniecki posted a discussion

Five Retrotec Products Added to BPI Product List

The Building Performance Institute, Inc. (BPI) has recognized five new products in its Product…See More
2 hours ago
Tom White's video was featured

New York energy policy & North American Passive House Network Conference

New York is increasing its energy standards and is investigating the possibility of implementing the Passive House Standard for new construction and retrofit projects. Interviewee: Ken Levenson, with NY Passive House Assoc and 475.
2 hours ago
Profile IconRichard Hale, Joseph Schulman, Carol W and 1 more joined Home Energy Pros
3 hours ago
miguel pace posted a blog post

Choosing the right Cooling Tower Fan

The cooling towers are often found in industries and manufacturing units, which are basically the…See More
6 hours ago
John Nicholas commented on John Nicholas's blog post Indoor Air - How do you measure if it is Healthy?
"Tom,   Here it is!"
12 hours ago
John Nicholas commented on John Nicholas's blog post Indoor Air - How do you measure if it is Healthy?
"The issue of Indoor Air Quality in a home comes up very regularly for a Home Energy Auditor. People…"
12 hours ago
tedkidd replied to Michael D'Arcy's discussion Small video we created to promote Home Performance
"Great! So those are results measured a year after work, not modeled? That makes you a rare…"
17 hours ago

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service