# Furring out existing 2x6 rafters



## kirylm (Feb 11, 2012)

My house was built in 1941. It's 1.5 story with regular gable roof. We are planning on renovating our 2nd floor. I have few questions about the approach i have chosen.


















Existing rafters are 2x6 and 15' in length, span is 14'' o.c. The floor joists are 2x8 and joined from two pieces in the middle (each joist basically consists of two pieces). They are 12' in length (each, making total length of a bit less then 24'' because they overlap like 5''). I attached the picture. There are 2x4 collars nailed every other rafter.

I am planning on furring out rafters and ridge board with 2x4 douglas firs, creating an air channel (smth like 1'' from sheathing) along the space between rafters by using plywood wrapped in radiant barrier foil (exterior side), then putting unfaced R-30 insulation and plastic sheeting for for vapor barrier.

I will use simpson hardware. 3x7, 16ga plates for rafters, 6x2 12ga angles for reinforcing rafters to the ridge board, 9x1.5 16ga angles for reinforcing rafters to the floor joists.

Then, since i am adding weight to the rafters, i am planning to reinforce floor joists in the place where they connect together in the middle. I am thinking of using some simpsons plates and corners, and/or bolting them together.

I will be putting new subfloor using 4x8 boards, and then nailing hardwood floor. Also plan to add some knee wall cabinets.

Here are the questions:

1). By furring out rafters I will add weight to the roof structure (wood + metal plates & corners + plywood). Does this pose any structural problems? Should I reinforce the floor joists better (extend it with 2x4, etc.) then with just some hardware metal plates and bolts?

2). By removing collar beams I potentially increasing outward thrust, however, i don't think that those are helping much. The floor joists is really holding those rafters together. Therefore I plan to reinforce those joists. Question is: from what i described above , does it sound reasonable?

Thanks


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## joecaption (Nov 30, 2011)

I'm missing something, is your plan to take out that center supporting wall and the ceiling rafters to make a catheral celing?


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## kirylm (Feb 11, 2012)

no, no cathedral ceiling, i am keeping the floor. the picture's dimensions is not exactly correct, the height (from the ridge to the floor) is about 10'.


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## joecaption (Nov 30, 2011)

Looks like an attic not added living space.
How far is it from the tops of those rafters to the center of the ridge beam?


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## kirylm (Feb 11, 2012)

right, its an attic, but its finished to add living space.


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## kirylm (Feb 11, 2012)

joecaption said:


> Looks like an attic not added living space.
> How far is it from the tops of those rafters to the center of the ridge beam?


if i understand correctly, you are asking about the height in the middle from where rafters intersect with ridge board to the floor joists? then - its about 10 feet.


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## Joe Carola (Apr 14, 2006)

joecaption said:


> I'm missing something, is your plan to take out that center supporting wall and the *ceiling rafters *to make a catheral celing?


Joe,

You mean ceiling joists....right?


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## kirylm (Feb 11, 2012)

I am not removing ceiling joists


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## Nailbags (Feb 1, 2012)

"long the space between rafters by using plywood wrapped in radiant barrier foil (exterior side), then putting unfaced R-30 insulation and plastic sheeting for for vapor barrier"
Why are you placing a vapor barrier in? you don't need it in the attic except were the ceiling is and that is were the Kraft paper needs to be face down towards the living space. doing it from what you described sounds like your going to trap moisture.


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## kirylm (Feb 11, 2012)

right, the ceiling will be right on the rafters. i will be putting drywall on top of that plastic vapor barrier, so it will be facing living area.


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## Nailbags (Feb 1, 2012)

kirylm said:


> right, the ceiling will be right on the rafters. i will be putting drywall on top of that plastic vapor barrier, so it will be facing living area.


Don't just use the Kraft faced batts it is a whole lot better. the Plastic is how can I say like placing your head is plastic bag and expecting to breath fresh air! if you do that you get water vapor on the plastic and in contact with the sheet rock and then you get mold. and damp sheet rock and more problems. I just wish who ever came up with placing plastic sheathing over insulation would be around to to repair the moisture damage it causes.


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## kirylm (Feb 11, 2012)

> Don't just use the Kraft faced batts it is a whole lot better. the Plastic is how can I say like placing your head is plastic bag and expecting to breath fresh air!


thanks for the advice

still my other questions are unanswered


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## Nailbags (Feb 1, 2012)

your floor joists are 2x8 correct? can you read a lumber stamp? if you can can you tell me what kind of lumber it is? is it Doug fir larch? or Doug fir?


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## kirylm (Feb 11, 2012)

Nailbags said:


> your floor joists are 2x8 correct? can you read a lumber stamp? if you can can you tell me what kind of lumber it is? is it Doug fir larch? or Doug fir?


hmm.. i doubt that I will get that, but i will definitely try. does it matter that much?


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## Nailbags (Feb 1, 2012)

yes it does I can give the formula for the tinsel strength of each types of wood and how much they can hold. Doug Fir Larch is the strongest, then Doug fir then Hem Fir then southern white pine then yellow pine the weakest.


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## Nailbags (Feb 1, 2012)

go to this link it will help you out the best.

http://www2.wwpa.org/


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## Gary in WA (Mar 11, 2009)

You may need a vapor retarder or a vapor barrier, or simply nothing there......

Where are you located?

Gary


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## kirylm (Feb 11, 2012)

GBR in WA said:


> You may need a vapor retarder or a vapor barrier, or simply nothing there......
> 
> Where are you located?
> 
> Gary


South NJ


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## Gary in WA (Mar 11, 2009)

Thanks, it appears you are in Zone 4; http://www.spore-tech.com/viewCategory.asp?idCategory=78 Check under the map for the major City listed close by.

R-38 is required in the ceiling; http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec002.htm

This will give you some new guidance: http://docs.google.com/viewer?a=v&q=cache:EJENK_uA9RQJ:www.cr-ar.com/pdfs/Building%2520Code%2520Changes.pdf+R602.3(1)+2006&hl=en&gl=us&pid=bl&srcid=ADGEESh311Kosslp7jsjp9WhUXxZsgSiyNaWb-eW0YminVwmPUavLlW75BKLoV9em4LFCAydmTGQlkUFOPm8AqHkRP5wLQGQQGkwyzAGtlN4D2DqCiCLwprOpEbvvjeGk6CEhyHiVdtK&sig=AHIEtbRa4Ah_IICPQ3BR1txlzU01V4JQIg

Egress stairs, egress windows, smoke detectors, etc. are all required. A permit is required for the "change of use" and the paper trail is essential for any H.O. Insurance future claims and at resale time.

The vapor barrier requirements: http://www.buildingscience.com/docu...heet-310-vapor-control-layer-recommendations/

Gary


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## AndyGump (Sep 26, 2010)

Hi, I don't mean to be an a$$ but there are a ton of things that I can see that might be wrong with your plan.
For now I will just concentrate on the following:
It sounds like you are going to have to install ridge venting and eave venting for every eave.

Have you made plans for this?

Andy.


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## kirylm (Feb 11, 2012)

AndyGump said:


> Hi, I don't mean to be an a$$ but there are a ton of things that I can see that might be wrong with your plan.
> For now I will just concentrate on the following:
> It sounds like you are going to have to install ridge venting and eave venting for every eave.
> 
> ...


Yes, the ridge vent is already there, I will add eave venting (sort of soffit vents) later on.

What other things are wrong?


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## Gaines21 (Feb 12, 2012)

Really cool post, highly informative and professionally written..Good Job


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## kirylm (Feb 11, 2012)

Nailbags said:


> your floor joists are 2x8 correct? can you read a lumber stamp? if you can can you tell me what kind of lumber it is? is it Doug fir larch? or Doug fir?


Found a stamp that says: SPIB No.1 (433)
Can you post that formula you mentioned?
Thanks!


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## Gary in WA (Mar 11, 2009)

http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_5_sec002_par017.htm

What is the end result for this space?

Gary


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## kirylm (Feb 11, 2012)

GBR in WA said:


> http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_5_sec002_par017.htm
> 
> What is the end result for this space?
> 
> Gary


Finished bedroom


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## Joe Carola (Apr 14, 2006)

kirylm said:


> Finished bedroom


You'll need permits...inspections....egress window.


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## kirylm (Feb 11, 2012)

Joe Carola said:


> You'll need permits...inspections....egress window.


I appreciate all the advices.

Just to make it clear, currently that area has 2 finished bedrooms. I am not creating any new living space, just re-doing the existing design. The problem originated from the fact that it gets hot (way too hot) in the summer, and too cold in the winter. That's why the whole idea of putting proper insulation, creating air channels, etc. Plus i wanted to install knee-wall cabinets and put hard wood floors instead of carpet.

It does have large windows, much wider then the 1st floor (I guess that is considered egress?) I never heard of egress windows on the 2nd floor, they usually do this in the basements...


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## Gary in WA (Mar 11, 2009)

Egress windows are to enable a fireman with an oxygen tank on his/her back to get in/out safely; http://www.aacounty.org/IP/Resources/FinishBasementGuide.pdf

The 5.7 sq.ft. clear-opening window is reduced for at grade windows: http://docs.google.com/viewer?a=v&q...r-YVo5&sig=AHIEtbRXqPqFUGZ6B_c_33otStRi7Aff7g

Gary


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