I've tried to maximize outgassing ever since the polyurethane spray foam was installed in January. But it the past few weeks, I've pushed it harder. I run the ceiling fan 24 hours a day. I added three 40 watt incandescent light bulbs which I run continuously so that there is infrared energy inside the building 24/7 also, and therefore a little extra heat, which might be especially helpful when it cools slightly in the early morning. The forced heating from the light helps prevent the outgassing from reversing temporarily when it gets relatively cool in the early morning. Or at least that was one of the ideas that inspired it.
On Sunday night, I noticed that the smell could be smelled twenty or more feet away from Lyndhurst on the outside. I had two ideas: the air was so still that the smell wasn't actively being blown away from my property. The air was very humid, so the formaldehyde was essentially "going into solution" with the humidity in the air. The latter image was very compelling, and I imagined that if nothing else the smell outside the building suggests that the outgassing rate is high for some reason, probably the humidity. But this special case of high heat (it was still above 90 at 10pm) and humidity was not well being taken advantage of, I thought, because there was no breeze or fan moving air into or outside the building.
So I moved the new fan I bought last week from my master bedroom (where it had proven quite nice for a few days) to Lyndhurst, which was what I bought it for.
While I typically see winds from the east, particularly the SE, on Sunday night the air was moving in very slowly from the north. So I cranked the Fleetwood casement window all the way open, and I felt a tiny bit of air movement inward.
So I decided to place the new fan in the doorway, blowing out. That would tend to suck air in through the window, providing forced crossflow ventilation. Although I worried that the doorway is so wide that any air blowing out would be immediately cancelled out by air sliding back in, it didn't seem to work badly. With the fan running, I could feel air blowing out through the entire doorway, as if the doorway were operating as some kind of horn for expanding the airflow. And more air was coming in through the window. I found it worked fine with the fan a few feet inside the building also, so it would almost always tend to pull in air that was inside the building. And it would also tend to draw from the window just 6 feet or so behind it.
The fan blew all day on Monday. On Monday night, fearing rain, I closed the window slightly, but increased the fan speed from 1 to 2. That was actually at 1am in the morning. At about 4am I changed it back to 1, fearing the added noise might disturb the neighbor (though unlikely). Even at 2 the fan makes less noise than an A/C compressor.
I'm noticing that the smell seems more likely when there is heat, but maybe even moreso when there is humidity and just some lingering heat. I'm thinking that both water and formaldehyde are small molecules that can leak through the tiniest of pores (most building materials are vapor permeable). Also, water and formaldehyde are soluble, but formaldehyde has the additional property of attracting oily compounds. Anyway, the water vapor has a greater ability to leech out the formaldehyde when the humidity is high. The effect of humidity on formaldehyde emmission is well known, but not so often explained.
One nice thing is that once I finish the "outgassing" phase of the project, hopefully in mid September this year, and close the doors and start the climate control, the inside temperature and humidity will be controlled to points where there isn't much outgassing. If the humidity is below 50, and the temperature below 80, based on what I'm already seeing, I suspect there won't be much outgassing. Meanwhile, during the outgassing phase, I can force much more outgassing than will be possible under climate control.
It's also possible the watering I have done in the past few days around Lyndhurst has helped created a high humidity bubble around Lyndhurst which both increases outgassing and tends to hold on to the formaldehyde smell temporarily.
The high temperature outside reached over 100 on Monday and over 106 on Tuesday. With the fans blowing the hot air into and around inside the building, this is great for outgassing. I'm also thinking outgassing could be occuring on the "outside" of the building now, from the sheathing outward. Inside the sheathing there is a 1.5 inch layer of closed cell polyurethane which is about as hard and impermeable as metal. So formaldehyde in the sheathing plywood can't escape to the inside of the building, but it might escape outward, through the hardi panel, through gaps in the caulk, and through the bottom seams.
On Sunday night, I noticed that the smell could be smelled twenty or more feet away from Lyndhurst on the outside. I had two ideas: the air was so still that the smell wasn't actively being blown away from my property. The air was very humid, so the formaldehyde was essentially "going into solution" with the humidity in the air. The latter image was very compelling, and I imagined that if nothing else the smell outside the building suggests that the outgassing rate is high for some reason, probably the humidity. But this special case of high heat (it was still above 90 at 10pm) and humidity was not well being taken advantage of, I thought, because there was no breeze or fan moving air into or outside the building.
So I moved the new fan I bought last week from my master bedroom (where it had proven quite nice for a few days) to Lyndhurst, which was what I bought it for.
While I typically see winds from the east, particularly the SE, on Sunday night the air was moving in very slowly from the north. So I cranked the Fleetwood casement window all the way open, and I felt a tiny bit of air movement inward.
So I decided to place the new fan in the doorway, blowing out. That would tend to suck air in through the window, providing forced crossflow ventilation. Although I worried that the doorway is so wide that any air blowing out would be immediately cancelled out by air sliding back in, it didn't seem to work badly. With the fan running, I could feel air blowing out through the entire doorway, as if the doorway were operating as some kind of horn for expanding the airflow. And more air was coming in through the window. I found it worked fine with the fan a few feet inside the building also, so it would almost always tend to pull in air that was inside the building. And it would also tend to draw from the window just 6 feet or so behind it.
The fan blew all day on Monday. On Monday night, fearing rain, I closed the window slightly, but increased the fan speed from 1 to 2. That was actually at 1am in the morning. At about 4am I changed it back to 1, fearing the added noise might disturb the neighbor (though unlikely). Even at 2 the fan makes less noise than an A/C compressor.
I'm noticing that the smell seems more likely when there is heat, but maybe even moreso when there is humidity and just some lingering heat. I'm thinking that both water and formaldehyde are small molecules that can leak through the tiniest of pores (most building materials are vapor permeable). Also, water and formaldehyde are soluble, but formaldehyde has the additional property of attracting oily compounds. Anyway, the water vapor has a greater ability to leech out the formaldehyde when the humidity is high. The effect of humidity on formaldehyde emmission is well known, but not so often explained.
One nice thing is that once I finish the "outgassing" phase of the project, hopefully in mid September this year, and close the doors and start the climate control, the inside temperature and humidity will be controlled to points where there isn't much outgassing. If the humidity is below 50, and the temperature below 80, based on what I'm already seeing, I suspect there won't be much outgassing. Meanwhile, during the outgassing phase, I can force much more outgassing than will be possible under climate control.
It's also possible the watering I have done in the past few days around Lyndhurst has helped created a high humidity bubble around Lyndhurst which both increases outgassing and tends to hold on to the formaldehyde smell temporarily.
The high temperature outside reached over 100 on Monday and over 106 on Tuesday. With the fans blowing the hot air into and around inside the building, this is great for outgassing. I'm also thinking outgassing could be occuring on the "outside" of the building now, from the sheathing outward. Inside the sheathing there is a 1.5 inch layer of closed cell polyurethane which is about as hard and impermeable as metal. So formaldehyde in the sheathing plywood can't escape to the inside of the building, but it might escape outward, through the hardi panel, through gaps in the caulk, and through the bottom seams.
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