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Vapor retarder

Vapor retarder

New postby Dave F on Tue Oct 17, 2017 1:39 pm


I'm modifying a room in my house to be a 2nd bathroom. it used to be a sun porch, so 3 of the 4 walls and the ceiling are exterior walls/surfaces. My question is, does code require me to install vapor barrier/retarder on the interior of the studs (between studs and sheet rock)? I searched through the 2009 IRC, which my town goes by, and I didn't see a requirement for it. When you search for it on the internet, there is no clear answer, and everyone has strong opinions about it. I personally don't want to install it, but of course I will if I have to keep inspectors happy. I have done a lot of light construction in my life, most with a licensed contractor, and we never installed interior vapor barrier (granted this was 25 years ago). I also never found any in any remodel we did. I live in Connecticut, and my house is air conditioned in summer (window units). I will say that the room had a hot tub in it for over 12 years, and was unheated when it contained the tub. I recently gutted the room to the studs for this project, and found no evidence of water/vapor damage. The house itself is over 90 years old, and I have renovated many parts of it, no vapor barrier found or added, and no moisture damage to be found.

Dave F
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Joined: Wed Feb 10, 2016 12:15 pm

Re: Vapor retarder

New postby Jerry Peck - Codeman on Tue Oct 17, 2017 4:10 pm

Unless there is a Connecticut code which addresses vapor retarders/barriers other than in the Energy Code or Existing Building Code, and the referenced IRC, then, no, there are no requirements for vapor barriers/retarders - however, when installed, vapor retarders are to be installed in accordance with the manufacturer's installation instructions, such as on faced fiberglass batt insulation.

That said, here are some code sections to start with as the work you are describing should start under the Existing Building Code, specficially in Connecticut, the:
- 2012 IEBC (International Existing Building Code)
- - Section 202 General Definitions
- - Addition. An extension or increase in floor area, number of stories, or height of a building or structure
Alteration. Any constsruction or renovation to an existing structure other than a repair or addition. Alterations are classifed as Level 1, Level 2, and Level 3.
- - Change of Occupancy. A change in the purpose or level of activity within a building that involves a change of application of the requirements of this code.

- - Section 504 Alteration - Level 2
- - - 504.1 Scope.
- - - - Level 2 alterations include the reconfiuration of space, the addition or elimination of any door or window, the reconfiguration or extension of any system, or the installation of any additional equipment.

- - - 506 Change of Occupancy
- - - - Change of occupancy provisions apply where the activity is classified as a change of occupancy as defined in Chapter 2.
- - - - 506.2
- - - - - Changes of occupancy shall comply with the provisions of Chapter 10.

- - - Section 1001 General
- - - - 1001.2.1 Repair and alteration with no change of occupancy classification.
- - - - - Any repair or alteration work undertaken in connection with a change of occupancy that does not involve a change of occupancy classification shall conform to the applicable requirements for the work as classified in Chapter 4 and to the requirements of Sections 1002 through 1011.

- Chapter 8 is Level 2 Alteration
- - Section 811 Energy Conservation
- - - 811.1 Minimum requriements.
- - - - Level 2 alterations to existing buildings or structures are permitted without requiring the entire building or structure to comply with the energy requirements of the International Energy Conservation Code or the International Residential Code. The alterations shall conform to the energy requriements of the International Energy Conservation Code or International Residential Code as they relate to new construction only.

From the 2012 IRC, referenced in 8.11.1
- N1102.1.10 (R402.2.10) Crawlspace walls.
- - (R402.2.10 is the IECC Section for the same thing)
These sections address vapor retarders in crawlspaces.

All the above said, though, follow what your local AHJ (Authority Having Jurisdiction) says - makes life easier.
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Re: Vapor retarder

New postby Dave F on Tue Oct 17, 2017 4:21 pm

Thanks for the quick response. I do plan to go along with whatever the town wants, but I wasn't sure if it was required by code.

Thanks again.
Dave F
Posts: 11
Joined: Wed Feb 10, 2016 12:15 pm

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