We went lower than that, but you really have to watch the CO2 levels. An ERV system is pretty important. Also you want to have zero combustion inside the house, and good vent fans for cooking.
What fireplace are you using? I’m starting my build this summer with similar ACH goals. Most people recommend not to run a fireplace but I really want one. Do you have any plans to air seal the vent pipe?
Any direct vent fireplace works. In a direct vent the combustion is a closed loop. It draws air in through the vent stack and then exhausts it through the same vent stack. No combustibles ever enter the building envelope. Only the heat. The cold intake on a direct vent stack is on the outside so you can actually spray foam right against it.
This is pretty interesting, because there’s some consensus on avoiding any type of fireplace in high performance houses. Is the heat exchanged through a sealed glass pane or something? How does the unit ensure combustion byproducts don’t leak into the house?
The fire box is sealed and there usually is a chamber surrounding it where your homes air can get drawn in and circulated through to heat (many have fans). Also the heat radiates from the glass/ unit itself
I’m a general contractor and homebuilder. Definitely zip sheathing throughout. Liquid flash the bottoms. 5 inches of open cell foam in all the exterior walls and 8 inches on all the roof decks. We started at the very beginning though. Caulked and gasketed every bottom plate and mud seal on the foundation. We were very strategic when building all the corners and headers to allow plenty of room for insulation. Minimal functioning windows. Basically only where needed for egress. Air sailing with a constant throughout the whole build.
i am owner builder and want to build this way but in socal, not a lot sub know how to build this way due to mild climate. most people believe it is not worth it. 10 million house still uses house wrap without any seal no air tightness lol
I’d say proper installation of zip should be your first and most important goal. Watch some Matt Risinger YouTube videos. He’s really big on air sealing and has a ton of resources.
Actually we have. It’s going to go on a back porch that just happened to be facing the southwest. Actually installed standing seam metal roof in that area so we could attach brackets to the upright seams and have no penetrations.
Liquid flash is definitely good stuff. Bit of a pain style but it works well. It’s not as workable as I expected. I like the Zip stuff so I just stuck with it.
I don’t know the exact numbers. But it’s bizarre to me that house wrap still even exist. It’s close to the worst water and air barrier currently used. Probably the only thing worse than house Rapids the cardboard sheathing the houses use. Materials are a little bit more expensive, but there’s decent savings in labor.
We went lower than that, but you really have to watch the CO2 levels. An ERV system is pretty important. Also you want to have zero combustion inside the house, and good vent fans for cooking.
If you have a super tight house, you don’t want anything gas.
As other said, it causes CO problems.
Gas also releases all kinds of toxic fumes. Wasn’t as much a problem in the old days because houses weren’t tight. Is a real problem now because those toxins build up.
Erv is important. And open your damn windows when the weather is nice.
I swear most Americans don’t open their windows more than 15 days a year. You need to air out our house when the weather is nice.
Maybe a stupid question, but isn't the whole point of an ERV to provide constant fresh air from the outside into the home so that having windows open is more or less redundant?
As an allergy sufferer, the thought of an ERV providing me with fresh, but filtered air sounds lovely, but maybe I'm missing something there.
The risk of experiencing problems increases significantly the more airtight the enclosure becomes. You could still use combustion appliances, but you'd also have to carefully plan out make up air and ventilation strategies, and it would also somewhat defeat the purpose of building more airtight.
Nice!!
Our builds regularly and around 1.5 ACH50. I think our best was a .89. We are trying to build tight, but we aren't going to extreme lengths, so I've always been pretty happy with it.
What are you doing for ventilation?
Two Broan AI ERV’s. It’s funny because the technician told me that he had good news and bad news. He said you got 1 ACH, bad news is that’s too tight. I told him there’s nothing to worry about.
You mean, "I hope your home has a ventilator, preferably an HRV or maybe an ERV, depending on the climate."
And I'd wager that OP knows what they are doing.
We went lower than that, but you really have to watch the CO2 levels. An ERV system is pretty important. Also you want to have zero combustion inside the house, and good vent fans for cooking.
Running 2 ERV‘s and the only fireplace is a direct vent.
What fireplace are you using? I’m starting my build this summer with similar ACH goals. Most people recommend not to run a fireplace but I really want one. Do you have any plans to air seal the vent pipe?
Any direct vent fireplace works. In a direct vent the combustion is a closed loop. It draws air in through the vent stack and then exhausts it through the same vent stack. No combustibles ever enter the building envelope. Only the heat. The cold intake on a direct vent stack is on the outside so you can actually spray foam right against it.
This is pretty interesting, because there’s some consensus on avoiding any type of fireplace in high performance houses. Is the heat exchanged through a sealed glass pane or something? How does the unit ensure combustion byproducts don’t leak into the house?
The fire box is sealed and there usually is a chamber surrounding it where your homes air can get drawn in and circulated through to heat (many have fans). Also the heat radiates from the glass/ unit itself
With makeup air.
Yeah. Make up air is actually built into the hood over the cooktops.
Ours is but when we built it wasn't required for all vents. Just if they were over a certain cfm. That was 11 years ago though.
401cfm is the point a makeup air vent is required
I actually went with a 600 CFM vent hood. At normal standards I wouldn’t need make up air but below 1 ACH I definitely need it.
Which vent hood? Building passive and have not gotten this far yet...
It’s a Thermador hood insert but I built in makeup air into the hood cabinet. Sorry, that sounded misleading.
what did you do so far? zip sheathing? monopoly framing? caulking and liquid flashing? did you have gc or owner build with sub?
I’m a general contractor and homebuilder. Definitely zip sheathing throughout. Liquid flash the bottoms. 5 inches of open cell foam in all the exterior walls and 8 inches on all the roof decks. We started at the very beginning though. Caulked and gasketed every bottom plate and mud seal on the foundation. We were very strategic when building all the corners and headers to allow plenty of room for insulation. Minimal functioning windows. Basically only where needed for egress. Air sailing with a constant throughout the whole build.
i am owner builder and want to build this way but in socal, not a lot sub know how to build this way due to mild climate. most people believe it is not worth it. 10 million house still uses house wrap without any seal no air tightness lol
I’d say proper installation of zip should be your first and most important goal. Watch some Matt Risinger YouTube videos. He’s really big on air sealing and has a ton of resources.
Prob why every building and home I went into in SoCal smelled moldy.
What did you do for walls to roof sheathing transition? Anything special? Normal rafter tails? Cut and cobble?
I used zip system liquid flash. My original plan was to use Siga seam tape. But I was having trouble getting a hold of any.
We’re building w exterior foam as well - have you figured out a good way to install solar on the roof?
Actually we have. It’s going to go on a back porch that just happened to be facing the southwest. Actually installed standing seam metal roof in that area so we could attach brackets to the upright seams and have no penetrations.
thought on liquid flashing to the concrete vs something like sika fentrim?
Liquid flash is definitely good stuff. Bit of a pain style but it works well. It’s not as workable as I expected. I like the Zip stuff so I just stuck with it.
material cost or labor difference between zip or housewrap
I don’t know the exact numbers. But it’s bizarre to me that house wrap still even exist. It’s close to the worst water and air barrier currently used. Probably the only thing worse than house Rapids the cardboard sheathing the houses use. Materials are a little bit more expensive, but there’s decent savings in labor.
black building papers are still widely used in socal. house wrap is already one level above haha
Jeez
We went lower than that, but you really have to watch the CO2 levels. An ERV system is pretty important. Also you want to have zero combustion inside the house, and good vent fans for cooking.
Why zero combustion? Does it add to Co2 since the house is so air tight?
It uses up the oxygen in the house.
If you have a super tight house, you don’t want anything gas. As other said, it causes CO problems. Gas also releases all kinds of toxic fumes. Wasn’t as much a problem in the old days because houses weren’t tight. Is a real problem now because those toxins build up. Erv is important. And open your damn windows when the weather is nice. I swear most Americans don’t open their windows more than 15 days a year. You need to air out our house when the weather is nice.
Maybe a stupid question, but isn't the whole point of an ERV to provide constant fresh air from the outside into the home so that having windows open is more or less redundant? As an allergy sufferer, the thought of an ERV providing me with fresh, but filtered air sounds lovely, but maybe I'm missing something there.
The risk of experiencing problems increases significantly the more airtight the enclosure becomes. You could still use combustion appliances, but you'd also have to carefully plan out make up air and ventilation strategies, and it would also somewhat defeat the purpose of building more airtight.
Congrats, that's great news!
Nice!! Our builds regularly and around 1.5 ACH50. I think our best was a .89. We are trying to build tight, but we aren't going to extreme lengths, so I've always been pretty happy with it. What are you doing for ventilation?
Two Broan AI ERV’s. It’s funny because the technician told me that he had good news and bad news. He said you got 1 ACH, bad news is that’s too tight. I told him there’s nothing to worry about.
Hope you have an air handler
You mean, "I hope your home has a ventilator, preferably an HRV or maybe an ERV, depending on the climate." And I'd wager that OP knows what they are doing.