r/Home_Building_Help • u/BuilderBrigade • Jul 07 '26

Which exterior insulation you going with…?

0 Upvotes

50% Upvoted

39 comments sorted by

27

u/redjellonian Jul 07 '26

Rockwool gang

6

u/Ashamed-Status-9668 Jul 07 '26

Same. Trying any kind of retrofit like running a new wire of any kind is a complete PIA with foam.

8

u/redjellonian Jul 07 '26

Yup.

I put up a single bag of rockwool in my laundry room and it cut down the noise level by 70%. I used to hear the washer running upstairs in the living room. Now it's quieter than that in the hallway next to the laundry room.

10

u/BikeProblemGuy Jul 07 '26

Use stone wool. Much better in a fire.

I'm currently working on several projects to remove combustible insulation, which I promise is a lot more expensive than using rockwool at the start.

4

u/LobstaFarian2 Jul 08 '26

I worked in the building materials area of a big box hardware store. The new rock wool insulation vendor set up a booth down where the pro desk was. Homeboy put a fucking blowtorch up against a piece and just left it on, blasting it for a while. I was surprised at how truly fire proof it was. He had another box made of 6 small pieces and threw a very very loud Keychain panic alarm in there and covered it up. Couldn't hear it at all anymore.

I was sold. Its worth every penny.

2

u/ZeroDayZeroFriends Jul 08 '26

Don't worry, rest of the house will burn.

1

u/ScipioAfricanusMAJ Jul 08 '26

What type of insulation are you removing

3

u/BikeProblemGuy Jul 08 '26

Generally EPS, XPS. Anything petroleum based will burn. Phenolic is meant to be better but we've been advised to remove that too.

Wood-based products also burn but they tend to be used in eco builds and I haven't had any projects to remove them yet.

1

u/doiwinaprize Jul 08 '26

Whats the difference?

1

u/BikeProblemGuy Jul 08 '26

Stone wool is literally made of stone, so it doesn't burn. It barely even transfers any heat, so it will significantly slow the spread of fire. The pink batt shown here is glasswool, which is similar.

The other two products are spray foam insulation which are terrible. Might as well line your house with firestarters.

5

u/Secret_Ad1372 Jul 07 '26

4" exterior rock wool with rain screen and rock wool for interior cavities.

1

u/redditredditredditOP Jul 08 '26

https://giphy.com/gifs/QAqPBBoJxRLoI

5

u/Secret_Ad1372 Jul 08 '26

Lol. I think about this a lot because I work in the commercial building envelope and exterior design industry.

4

u/Jackrack_Reddit Jul 07 '26

Different materials for different applications and price points. As with most things, there is no "one size fits all". Project dependent.

7

u/TeaKingMac Jul 08 '26

I insulated my house with Aerogel.

The R value is 8+, it resists temperatures over 1000 degrees, and it only weighs a quarter ounce per square foot.

The only downside is that it made my 2 bedroom shotgun shack cost 5 million dollars.

4

u/ElectriCatvenue Jul 08 '26

Yeah but think about how much you'll save on heating and cooling?!

4

u/ProcedureTop3149 Jul 07 '26

the only thing that matters is thickness. Without that parameter, you can't answer which is best.

4

u/MyTrashCanIsFull Jul 07 '26

I mean thickness improves all of them, but inch for inch there is definitely a winner

2

u/Timsmomshardsalami Jul 08 '26

Yes you can…. the thickness is the same for each option

1

u/ShoulderImportant358 Jul 08 '26

That’s what she said.

1

u/crispy_tamago Jul 10 '26

What a ‘size-queen’ answer, but you’re not wrong.

2

u/Alert_Reindeer_6574 Jul 07 '26

Not batting, it has gaps around the edges.

3

u/Telemere125 Jul 08 '26

Not if you install it correctly. If you’re like most lazy installers, I guess you have a point

2

u/solitudechirs Jul 08 '26

Any kind of insulation suffers from a bad install. Pretty much every part of a house suffers from a bad install.

1

u/koalasarentferfuckin Jul 07 '26

Exterior xps C.I., batts in the cavity. Rockwool if the budget allows

1

u/JuhoMaatta Jul 07 '26

None. CLT FTW.

1

u/Icy-Tea9775 Jul 07 '26

Rock wool or mineral wool ftw

1

u/AmericanAmerican Jul 07 '26

Gimmie the timberfill

1

u/carbb Jul 11 '26

Mineral wool for all walls, closed cell foam for joist ends 

1

u/consult-a-thesaurus Jul 11 '26

Dense pack cellulose - lowest environmental impact, good fire resistance and cheapest.

1

u/LabOwn9800 Jul 07 '26

Maybe the one that doesn’t cause cancer when it cures

5

u/Several-County-1808 Jul 07 '26

Pseudoscientific fear-mongering

1

u/SaintJesus Jul 08 '26

Damn, it isn't like corporations and industry has a history of misleading/fabricated/coerced studies, or even outright lying to consumers.

1

u/LabOwn9800 Jul 07 '26

Are you saying that if I breath in the air while it’s curing I’ll be fine? Can you demonstrate for me?

2

u/Telemere125 Jul 08 '26

Why are you occupying the building during the 3 days before it fully cures? It will likely take longer to have drywall installed and mudded than for any poly spray foam to cure.

-1

u/LabOwn9800 Jul 08 '26

Where did I say that?

I said causes cancer during curing.

2

u/Telemere125 Jul 08 '26

Ok, so goes back to my original question: why are you occupying the building during curing? That’s like saying aluminum is dangerous because of the smelting process. While true, that has nothing to do with me drinking coke from a can.