Insulation Question

noway2

noway2

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As part of the house renovation we're doing, we plan to replace (most of) the old insulation, as well as insulate the interior walls for sound dampening. It turns out that there was a miscommunication with the insulation crew, and they apparently thought we were going to do the minimal job and only put (new) insulation where the old stuff was missing and in the new area that was a car port. One thing I noticed, which leads to my question, is that the new insulation does NOT have a vapor barrier on it. I have been trying to read up on whether or not a vapor barrier is required in our climate (Central NC - a bit south of and between Greensboro and Raleigh) but can't get a definite answer.

Does anyone have an expert opinion on this subject?
 
Vapor barriers are an old thing that isn't used in most modern construction. I've been in the construction field for 26 years and come from a family of carpenters. A house needs to breath and the vapor barriers of old days is a main reason there's so much rotten framing in old houses. They still use them in trailers and modular houses and you can take the wall covering off of a 10 year old modular or trailer and there will be signs of water damage and it's mostly due to the vapor barrier not letting things breath.
 
It’s been a long time since I looked, but building code used to require a vapor barrier for exterior walls and crawls “ceiling”, but not for the attic. Vapor barrier faces the conditioned space.
 
GymB said:
It’s been a long time since I looked, but building code used to require a vapor barrier for exterior walls and crawls “ceiling”, but not for the attic. Vapor barrier faces the conditioned space.
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You are somewhat correct. Vapor barrier is needed on outside of exterior walls between sheathing and siding. Now days tyvek is mostly used over tar paper and such from the past cause tyvek can breath. Although tar paper is still acceptable for outside wrap between layers. But no barrier is needed on the inside of exterior walls like they used to do with tar paper or plastic. And as for the barrier in a crawlspace it's always a good idea in my opinion but is not required unless your crawlspace is I believe 18 inches or closer to the ground.
 
BTW, can see this changing as building wraps got better over the years.
Knew a guy that build a house entirely with concrete filled (I think) plastic blocks that were sealed to each other, it was by design impervious to air and moisture…inspectors still insisted that he wrap it.
 
I was watching when they put the insulation in the floor of the now enclosed car port. Its pretty thick, but I don’t recall a vapor barrier on it. Obviously it passed inspection, so I assume it meets the codes. The new exterior has Tyvek, but the original part of the house, built in 1971 doesn’t. I think it has tar paper between the sheeting and the brick. Since we took down most of the Sheetrock, we are going to re insulate where it’s exposed. Most of it is really nasty looking anyway and as much as we’re doing, I should have taken it all down. It looks Ike it picked up smoke from the original owners being tobacco users. The barrier is dark and oily looking. See this picture for example.

IMG_0519.jpeg
 
I've done jobs where the inspector wouldn't even get out the car and just pass the job. And I've done jobs where you get that one inspector that finds some kind of little bs on everything that gets done so he can fail you over and over again. I've even had to call the state and request a new inspector on one big remodel I did years ago. And when the new inspector came in and passed all my work that had been constantly getting failed by first inspector I found out the first inspector lost there license after that for unfare practices or something like that.
 
HandyDave said:
I've done jobs where the inspector wouldn't even get out the car and just pass the job. And I've done jobs where you get that one inspector that finds some kind of little bs on everything that gets done so he can fail you over and over again.
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I recall the discussion over the framing of the enclosed car port floor. He asked if they were going to stick build it or use engineered trusses. The answer was stick build, and he said use 3 stacked 10x’s and he could follow the stick built rules. It’s got the 3x 10xs and hurricane hangers and pillars. The GC knew we plan on putting a 1,000 lb pool table on it and built it accordingly.

Oddly, there is about 13” to the concrete slab beneath, which has plastic under it. There are sufficient vents and a big enough access to the crawl space under the house, but we made sure to put NO infrastructure underneath.
 
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On our most recent reno we installed all new drywall and insulated both interior & exterior walls with Roxul Comfort Batt R15 rock wool insulation. No paper vapor barrier on the exterior walls other than the existing house wrap.

Compared to fiberglass batts this stuff is easier to install and stays in place without sagging, it also allows you to completely fill the space around blocking, boxes and pipes.
 
I'm not sure what they were using. It's white, so I don't think it's rock wool, but looks denser than the spun pink fiberglass. There are some bags in the dumpster so I'll have to look.
 
Update: they showed up today, but didn’t get the instruction to remove all the old R11 and replace it with R15. The inspector passed the job and said he doesn’t need to see if we replace the R11. Sheetrock delivers this afternoon, to be installed next week. One of the crew either doesn’t speak English or pretended to not. He said something in Spanish, I replied, “Lo siento, solo hablo un poco español”. He chuckled, said OK, then went quiet.
 
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