Comment by hourislate | Hacker News Reader

Comment by hourislate | Hacker News Reader

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Some things to consider.

This guy needs to learn more about insulation before attempting an ROI. The average new build has 2000 ft of linear cracks that allow airflow. It's like keeping your front and back door open all year around. Batt Insulation is rated to make batt insulation look good. It does not seal out airflow. If it were great wouldn't we use it in our freezers and refrigerators?

If you want to use Insulation than I would suggest Spray Foam (closed cell or open cell).

https://www.demilec.com/

It not only provides an air seal but can also act as a vapor barrier and is mold/mildew proof and has no nutritional value for pests or bugs. Closed Cell Foam (2 lb -it;s called 2 lb because a cubic ft weighs 2 lb)will strengthen the racking strength of a framed wall 200%. The foam is basically free because after a few years it will pay itself off and it will last longer than your house. I've seen walls in schools sprayed 30 years ago that still look like they were done yesterday.

Unfortunately the mechanical of a house is hidden behind drywall. So it is out of sight and and of mind. People will not hesitate to spend 50k on a kitchen that can be replaced at some point without knocking down the house but they will look at you like you raped their sister and killed their mother when you give them a quote for 20k to spray their whole house. You get one chance to do it right and not to many people care.

Here is a shot of spraying the outside of a foundation wall. The entire inside was sprayed foamed also. This spray foamed foundation stops the cold from even getting to the outside walls. Many schools and commercial buildings are done like this.

https://imgur.com/a/bZGyUJk

This house has geothermal HVAC and is entirely sprayed foamed. It has a fresh air recirc to keep it all healthy. HVAC bills are trivial, comfort is incredible in -40 or 100 +. I would be surprised if it cost more than $800 - $1000 a year to keep at a steady 78 in the winter and 72 in the summer. When the wood stove is going it heats the entire 2800 sq/ft house. You can't even hear thunder or heavy winds.

It was 24k to spray everything (2800 SQ/FT house). A little cheaper than the kitchen if you count the appliances.

I did my house with a 2lb closed cell foam, and could not be more pleased with it. I had the (mis)fortune of getting hit by a major hurricane so the house had to be gutted to the studs. I ended up doing it myself with a fastkick binary gun as I already had an 80 gallon compressor. Ended up costing me 7k to do right at 2000 sq.ft, at an average depth of 3 inches, including under the floor (we are on a pier system) and the ceiling. We put foam board up in the attic and shot the foam between the rafters to the foam board, so there is a little extra insulation there.

Maybe I'm just getting sensitive in my old age, but IMHO there's no benefit to using brutal metaphors involving rape and murder when talking about insulation. I appreciate your comment otherwise though.

It's worth noting that spray foam insulation has significant CO2 impact (measured as GWP). Some estimate is to have a payback time of 50-60 years (although the manufactures dispute the numbers)[1]. We have opted for cellulose insulation for our new house, which has most of the insulation advantages without the environmental impact.

[1]https://www.architectmagazine.com/technology/products/produc...

I can speak from experience, that insulation which forms a vapor barrier is not compliant with the residential building codes in Austin, TX and likely many other places due to the climate of the area.

Additionally, in the UK, many houses had this spray insulation inserted into their wall cavities, and the additional vapor barrier resulted in major damp and mold problems.

In warmer climates like Austin/TX, you use 1/2 lb (Open Cell) to a depth of 6 inches. It does not create a vapor barrier.

It's all about warm side/cold side and the dew point.

Demilic is based in Arlington TX.

to further geek out:

* If air temp will never cross the dew point, you don't need a vapor retarder.

* Though the normal is "vapor retarder on the hot side", they can be on the outside of the wall assembly if condensed water can drain away. This is important for climates that have heavy heating and heavy cooling seasons, or for it's easier to put it on the outside.

Closed cell foam is amazing. Air and vapor barrier, high R-value, cures hard and semi-structural. Expensive, but worth it.

How about rockwool? It seems like it has a lot of advantages: soundproofing, termite resistance, hydrophobic, fire resistance, recycled content, inexpensive. What am I missing?

Rockwool is excellent. It's not an air or moisture barrier on its own, but combined with spray foam, it's best of both worlds. They call it "flash and batt" and it's an approach that's more and more widely adopted.

What's the environmental impact of CCF?

I'm starting out on a dream home project, but get uneasy thinking I'm building a house from lots of fossil fuel and concrete.

There's such a thing as 'green concrete' but the way its marketed smells like a pending dieselgate.

I'm currently leaning towards straw-bale and timber (I'm building in forests), but want lots of glazing and that seems really bad environmentally too.

> What's the environmental impact of CCF?

Did you consider the total impact of your new house throughout its whole life? Even though CCF may be fossil-fuel based (disclosure: I have no actual idea of how CCF is created), if it saves a lot of energy (which is probably extracted by fossil fuels as well) it may easily be a win for the environment.

Yeap, environmental impact is the whole life thing, total.

We are literally replying to someone saying that the CCF will outlive the house!

I've done a bit of amateur archaeological digging and the viking houses are just stains in the ground, showing where the post holes once were. There's a beauty in that, I think.

Whereas in a thousand years will people be digging up CCF with the imprint of timber studs? Yuck!

Spray foam is way too expensive and should only be used in extraordinary cases. For a new house I'd just use a layer of polyiso on the outside to reduce thermal bridging and regular fiberglass batts between studs. If you really want high R-value, double stud construction with blown in is probably the most cost effective.

$3 sq/ft at 3 inches thick and provides an R21 and a complete air seal and vapor barrier. That's less than most people spend on carpet.

Are people considering insulating with carpet as an alternative to foam? No one: “I was going to use foam, until I realized that, for just a little more money I could put carpet in the walls.”

I used closed cell foam in one room that I tore back to the studs. It’s easily the most comfortable room in the house, so I like the product, but comparing the price of non-substitute goods seems not useful. Compare foam to other insulation products.

No but they won't hesitate to spend money on (8 sq/ft) something that will war out and they can easily change but something that you basically get one chance at and it determines your environmental quality and comfort, they could care less.

I take it you never worked in construction or home building and gave quotes. You would understand how people don't even give the mechanical any consideration (waste of money) but will spend 10's of thousands on cosmetics. You could build their foundation out of lego but you better use marble and gold leaf in their bathrooms.

I have not, but on the customer side, I have tried to buy mechanical services from salespeople who can't intelligently explain the value of the different choices or answer fairly basic questions about anything other than cost and schedule.

I'm a mechanical engineer (non-practicing) and generally in a position to buy something well above the entry level "we do 50 of these jobs a month" so if someone could manage to make a cogent explanation, they stand to get the sale over the other two jokers who have probably explained how "the basic system is just fine; no one ever complains" or "hey, the whole job is less than 1 Bitcoin [or other irrelevant reference]". I have a plumber that I trust; he wasn't the cheapest. I have an electrician that I trust; he wasn't the cheapest. I have an insulation contractor; he was FAR from the cheapest but did an excellent job, so he'll get the return call as well. [He was the only one who didn't make obvious blunders in the bidding process; my favorite was the one who recommended I pay an extra $1000 for him to spray foam my rim joists; said it was the best money I could ever spend. I have a structural brick house with no rim joists, so I took him down to the basement to have him point out what he was proposing to do; hilarity ensued, of course]. I wish I could find a good HVAC contractor. I'm 0 for 2 so far there.

Fiberglass batts are 4x cheaper for the R value and can be DIY. Spray foam cannot be easily added to an existing home without a professional coming out. (except for the cans used for air sealing gaps.

It's essentially a waste of money except for limited applications, which is why you won't find any builders at any price point using spray foam as a primary source of insulation.

Spray foam is also a pain if you need to get into wall/ceiling cavities for HVAC/plumbing/electrical repairs/additions.

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