New addition
jam1030
| Posted in Green Building Techniques on
I have added a new addition on back of house. Live in south Alabama. The addition used to be a covered screened deck and now has been completely enclosed with windows and will be heated and cooled.
I have used 2×6 walls and 2×10 floor joist along with 2×8 ceiling joist. The walls studs have osb, house wrap and then hardie siding.
Thinking of using R23 rockwool in walls, R30 blown in for ceiling, not sure for floor.
Questions are is rockwool ok for walls with no additional vapor barrier? Also what would be best for floor as it is elevated about 4 feet above ground and is a vapor barrier needed there as I will use a laminate floor.
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Can someone help?
Jam1030, almost all of Alabama is in climate zone 3A, with a couple of counties in zone 2A. Assuming you're in zone 3, minimum 2015 IRC requirements for your zone include R-20 cavity insulation at walls (or R-13 cavity + R-5 continuous exterior insulation); R-13 in raised floors, no insulation required under or around slabs, and R-38 in roofs or ceilings. There is usually a return on financial investment and improved comfort in going above code. There is no excuse for going below code on new construction or additions.
Vapor retarders are not required in your climate zone.
I suggest paying attention to airtightness.
For more information, check out table N1102.1.2: https://codes.iccsafe.org/content/IRC2015?site_type=public/chapter-11-%5Bre%5D-energy-efficiency#IRC2015_Pt04_Ch11_SecN1102
Thanks for the reply. Actually, I am in zone 2a. Right at the bottom of state.
Any particular recommendations for under floor? I don’t particularly like fiberglass but could use it and I read where you can protect it using foam board and/or osb. Also is it a problem to leave an airspace between insulation and bottom of joists especially if I put foam board on bottom of joist to protect insulation from critters? I have 2x10 joist but if I use r19 that won’t fill space
Hi Jam 1030.
In addition to Michael's comments, and assuming that the floor is raised (since this was formerly a deck), you may find these two articles helpful: How to Insulate a Cold Floor, Insulating a Wood-Framed Floor Assembly