Spray-foam insulation makes homes unable to be mortgaged • Hacker News Board

Re: Spray-foam insulation makes homes unable to be mortgaged

#131

Post by CyberDildonics » Tue, Aug 13, 2024, 2:07 PM UTC

lm28469 wrote: post #127

CyberDildonics wrote: post #108

Earlier quoted context omitted.

Why would water be able to get through your roof but air not be able to get to it at the same time? Why would water be able to get through your roof with spray foam making anything worse? Water damage means you have to replace things anyway.

> Why would water be able to get through your roof with spray foam making anything worse? Because your roof _will_ fail, they all do, once it does the water will collect between the roof and the foam, because while it's not air tight there will be nowhere near enough ventilation do get rid of it > Water damage means you have to replace things anyway. Yes, but if your entire wooden structure rots for 5 years because y…

Because your roof _will_ fail

You said that already but it doesn't answer any of the questions I asked. Repetition doesn't make something true. There are typically shingles, then a layer underneath, then wood sheathing like OSB. All that is for the cheapest roof.

https://diy.stackexchange.com/questions/32820/is-it-ok-for-o...

once it does the water will collect between the roof and the foam

Says who? If water is getting to the wood, why isn't air getting to it? Typical roofs last for 20-30 years.

This idea that foam is bad because seeing water soak through through the entire wood sheathing is nonsense. This is also only dealing with foam on the underside of the roof, which is also not the only place or way it can be used.

but if your entire wooden structure rots for 5 years

Now your "entire wood structure" is going to rot? If you want to know if there is moisture in your wood, go in your attic. This idea that roofs blow off without anyone noticing and huge amounts of water soak all the wood in a house and the entire thing rots without any indication is not reality.

feel free to google it if you don't believe me.

You can feel free to google it because you're the one making the claims.

Re: Spray-foam insulation makes homes unable to be mortgaged

#132

Post by throw0101d » Tue, Aug 13, 2024, 4:39 PM UTC

kazinator wrote: post #130

throw0101d wrote: post #129

Earlier quoted context omitted.

> If you ventilate, you're bringing in hot air in the summer or cold air in the winter; it completely defeats the purpose of the insulation. ERV. Build tight, ventilate right. — Perera and Parkins; https://www.aivc.org/sites/default/files/airbase_5952.pdf , https://www.cibsejournal.com/technical/build-tight-ventilate...

I don't see the point of building tight, if you're going to have massive holes in the building, through which you force tons of air (which you should). Would you call a jar airtight if you never close the lid? In multi-tenant dwellings, building tight can help keep people's smells to themselves. That's about it. Like if you have pressurized air in the hallway, keeping the common area fresh, if the apartment units are…

> I don't see the point of building tight, if you're going to have massive holes in the building, through which you force tons of air (which you should). Would you call a jar airtight if you never close the lid?

I'm not quite sure why you're taking thing so literally about combining the two actions. I would call a jar airtight because the glass cannot be penetrated by air, nor can the lid and band.

You can then ventilate the airtight (proverbial) jar on your own terms: using filters and such to control the quality of the air that goes in/out.

The build tight is about the building enclosure; the ventilate right is about exchange stale/dirty interior air with cleaner exterior air in a controlled fashion.

A fully sealed building with zero ventilation would be horrible for people due to increased chemicals from people just breathing (CO2) or cooking. It is absolutely necessary to ventilate a building, but it can be done so to also reduce the incoming undesirable elements in the exterior air.

> Ventilating forces out all that hot or cool air that you paid for, so you have to heat or cool the replacement air.

Ventilating using HRV/ERVs takes the conditioned air and transfers some of its properties (temperature, moisture) to the incoming air to temper it. The incoming air is/can be also filtered to removed things like pollen, dust, wildfire smoke, etc.

> It's basically greed or ideology over health.

There are entire industry standards (ASHRAE 62.1 and 62.2) on the topic of good indoor air quality (IAQ) to make sure that 'just enough' stale air is removed (e.g., to reduce CO2 counts) while not 'over-ventilating' (increasing costs), and it is a topic of active academic research (especially post-COVID):

* https://www.youtube.com/playlist?list=PLsc2-5fAgMq4bj2P8fMgQ...

By not having a tight building envelope treated air can leak out, and untreated air can leak in, and depending on the size of the leaks (holes) you can even get bugs/creatures entering.

The whole point of buildings is to separate environments: inside versus outside. Leaking building compromise that separation reducing the control you have. And if you do not want to separate your interior and exterior environment live in a tent or under a tarp: plenty of ventilation, very little air-tightness.

Re: Spray-foam insulation makes homes unable to be mortgaged

#133

Post by rascul » Wed, Aug 14, 2024, 1:09 AM UTC

hollerith wrote: post #121

rascul wrote: post #120

Earlier quoted context omitted.

Moisture barriers and vapor barriers are different things that are often confused. And sometimes a thing is both.

Can spray-foam insulation be a moisture barrier, though? My guess is no, it cannot.

Yes. That's the problem.