New Upstairs Bedroom

[tiredretired]

I have a small area on the end of our cape that we have used for storage. Not served by dormers and I am not willing to invest in that right now. So, I decided to build a small 16' x 10' bedroom for the occasional guest and for me when I am in the doghouse. Here is a pic of the project.

The roof rafters are 2x6 with a 12/10 pitch so the depth is not enough for poper insulation without furring out considerably. Spray in foam quotes were crazy high for the amount of work citing set up time and cleanup. So I opted for 6" of PolyISO board. This will give me a R48 on the sloped roof portion. Two iso boards between the rafters with a 1 1/2 air space under the roof boards for an air space from the soffett venting to the ridge venting.

The 2x4 wall gets R11 and then 1" of R8 PolyISO to achieve R19 rating.

Knee walls will have R21 Pink and 1" Poly iso facing for a R29 rating. Ceiling / Collar Ties will be insulated to R40. Floor behind Knee wall will have R40+ with wind breaks at the soffit end and foam air barrier under the knee walls between the floor joists. Floor decking is 3/4" Plywood tongue & groove. All seams and cracks caulked under 1/4" and foam sealed above 1/4".



Detail of insulation on knee wall behind outlet and CATV to maintain R29 or greater insulation rating at outlet location

 

[FrancSevin]

Since youare not spry foaming, put a6 mil poly barrier onthe outsidewalls and overthe studs.

Harder to do than just over the finished studs But will seal better. At least that is the gospel according to Mike Holmes.

I'm doing a second floor loft area over the On-Suite and common bathroom. 2X4 stringers from the trusses are my Joists which ain't Zactly' legal but no span is over 6 feet.

All the Stringers are sistered and tied with 5/4" decking, screwed not nailed. This covered with 1/4 plywood.

4 X 6 rafters are sistered and span only 8 feet from the knee walls, which are actualy 2X12 headers, giving me the minimum 80" in the center of the room. A couple of sky lights are in and, if needed a dormer, and the wife has her artist's studio.

Plumbing is in, Electric done. Insulation (pink fibreglass) complete. we are arguing over the stairwell without which I cannot bring up 4X8 panels to do the walls.

Did it all using the pull down ladder for access.

I like your use of 1/2" foam board.Lighter than dry wall and warmer. I used 1/4 foam sheathing and I am not impressed. That looks good TR.

 

[tiredretired]

Since youare not spry foaming, put a6 mil poly barrier onthe outsidewalls and overthe studs.

Harder to do than just over the finished studs But will seal better. At least that is the gospel according to Mike Holmes.

I'm doing a second floor loft area over the On-Suite. 2X4 stringers fromthe trusses are my Joists which ain't Zactly' legal but no span is over 6 feet.

All the Stringers are sistered and tied with 5/4" decking, screwed not nailed. This covered with 1/4 plywood.

4 X 6 rafters are sistered and span only 8 feet from the knee walls, which are actualy 2X12 headers, giving me the minimum 80" in the center of the room. A couple of sky lights are in and, if needed a dormer, and the wife has her artist's studio.

Plumbing is in, Electric done. Insulation (pink fibreglass) complete. we are arguing over the stairwell without which I cannot bring up 4X8 panels to do the walls.

Did it all using the pull down ladder for access.

I like your use of 1/2" foam board.Lighter than dry wall and warmer. I used 1/4 foam sheathing and I am not impressed. That looks good TR.

Actually Franc, that is 1" foam board on the outside wall and it will get 1/2" sheetrock over it. Code requires at least 1/2" rock over PolyIso board.

I wish I could have spray foamed but it was well above my budget and they still wanted me to furr out the roof rafter by 1 1/2" as they wanted to put 7" of foam insulation. The claim was I would not need the 1.5" air space between the insulation and the underside of the roof deck as I am doing now as the R rating would be so high as to preclude any roof icing. Not so sure about that in a Zone 7 winter climate. So I opted to do it myself. Hopefully I made the right decision, but money is money. It either fits the budget or it don't.

You did a lot of work there as well. Post some pics when you get a chance.

 

[FrancSevin]

Actually Franc, that is 1" foam board on the outside wall and it will get 1/2" sheetrock over it. Code requires at least 1/2" rock over PolyIso board.

I wish I could have spray foamed but it was well above my budget and they still wanted me to furr out the roof rafter by 1 1/2" as they wanted to put 7" of foam insulation. The claim was I would not need the 1.5" air space between the insulation and the underside of the roof deck as I am doing now as the R rating would be so high as to preclude any roof icing. Not so sure about that in a Zone 7 winter climate. So I opted to do it myself. Hopefully I made the right decision, but money is money. It either fits the budget or it don't.

You did a lot of work there as well. Post some pics when you get a chance.

It's not roof icing that you should worry, It is ventalation for the roof sheathing. keep at least 1 1/2" from the insulation to the sheathing as ventilation or your wood will rot in the summer heat. Sheathing and rafters.

as for my project, it is off the books and not going thru the permit process. I knew the county would not allow it.
There will be no drywall as the weight would be too much.

I have used several construction methods at which building inspectors would scoff. One of them is load suspension to transfer the weight of the project to the foundation. It is correctly engineered but an unconventional way to build.

So, questions questions and more questions.

I went thru this with engineered floor joists back in the 60's and 70's. Now common practice, I could not get approval on the concept from many building inspectors.

Today it is proven to be structuraly superior and is now common practice.

So not exactly legal but, my second floor is stronger and stiffer than the first. No inspection needed.