# 2x8 plank ceiling



## bluebird5 (Dec 13, 2010)

I am building a house with exposed ceiling joists with 2x8's on top of them. I am putting blown in insulation on top of that. Before I do, I was going to put down paper of some sorts on top of the 2x8s to keep dust and dirt from coming through the cracks. 

I was going to use tyvek, but I don't want to see the white through the cracks. Then I thought about using 15# felt paper. Do you think that would be sufficent or should I use something different?


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## griz (Nov 26, 2009)

Should be fine.

Can you get the 2x8 T&G?


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## bluebird5 (Dec 13, 2010)

No its just regular 2x8's butted together.


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## Golden view (Feb 16, 2012)

6-mil poly. It's even required in many places..


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## bluebird5 (Dec 13, 2010)

Golden view said:


> 6-mil poly. It's even required in many places..


HMM why the poly. It is not beathable. I was thinking something like plastic would make the house more humid because it will trap all vapor from cooking and showering ect.


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## Golden view (Feb 16, 2012)

Sorry, didn't see your location. I can't get my stupid head around places that aren't heating dominated. Felt sounds good. Nothing cheaper that I can think of.


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## bluebird5 (Dec 13, 2010)

Golden view said:


> Sorry, didn't see your location. I can't get my stupid head around places that aren't heating dominated. Felt sounds good. Nothing cheaper that I can think of.


Well I'm not really worried about the cost of felt vs poly. I just want to do whats best for the building. You kinda got me thinking the poly would be better now.


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## hdavis (Feb 14, 2012)

bluebird5 said:


> Well I'm not really worried about the cost of felt vs poly. I just want to do whats best for the building. You kinda got me thinking the poly would be better now.


You definitely don't want poly in your location. Personally, I'd consider a synthetic roofing underlay instead of felt. You still need to be able to seal all the seams to control air movement, and I don't think you want to be doing that with felt.


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## bluebird5 (Dec 13, 2010)

hdavis said:


> You definitely don't want poly in your location. Personally, I'd consider a synthetic roofing underlay instead of felt. You still need to be able to seal all the seams to control air movement, and I don't think you want to be doing that with felt.


I have thought about synthetic roofing underlayment also, but what is the different between that and the poly? Arent they both air and vapor tight?


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## hdavis (Feb 14, 2012)

bluebird5 said:


> I have thought about synthetic roofing underlayment also, but what is the different between that and the poly? Arent they both air and vapor tight?


The ones for metal roofs are very permeable, some of the woven ones for shingles are fairly permeable, too. They're similar to house wrap.


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## Tom Struble (Mar 2, 2007)

actually some are breathable and some are not

http://www.owenscorning.com/Network...efense-Technical-White-Paper-October-2011.pdf


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## bluebird5 (Dec 13, 2010)

So better not to use the plastic so the humidity can leave the living space?


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## Tom Struble (Mar 2, 2007)

is there any fire code issue that would require drywall behind the 2x?,while a vapor barrier may not be required,air sealing would still be important


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## bluebird5 (Dec 13, 2010)

going by 2006 international building code for 1 and 2 family dwellings. Can you think of anything it the code that saysd I need a fire block above that ceiling? 

Thats what i'm all confused about Tom. I need to seal the inside air in and let the humidity out as a typical drywall ceiling would. A drywall ceiling with no vapor barrier above it is typical construction practice in my area.


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## Rio (Oct 13, 2009)

If it was going to be T&G then I would think felt would be fine but if there's a concern about it gapping and showing then I don't think it would be so good, might even smell? I think the drywall or something similar on top of the 2x's is the way to go.


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## aaron_a (Dec 18, 2013)

What about a layer of t&g rigid foam?


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## Cal Sustainable (Nov 21, 2014)

Here's my ceiling with 2x6 doug fir installed straight from, I do actually really hate to say, the shall-not-be-named orange store. However, it was much cheaper and better quality than what my trusty real deal lumber yard was charging and supplying. 15# above, 1 1/2" rigid foam with sleepers, then 1/2" ply, 30# felt, 30 yr roof.

If you have the benefit of time on your side I HIGHLY suggest letting the wood dry as much as possible before installing it. As you can see, those gaps. They don't really bug me too much because it's my house and I don't care, but there's a good 3/16"-1/4" between every board. Just FYI. And, no smell to speak of...


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## hdavis (Feb 14, 2012)

Cal Sustainable said:


> Here's my ceiling with 2x6 doug fir installed straight from, I do actually really hate to say, the shall-not-be-named orange store.


It's the only place close to me that stocks doug fir (2X4 up to 2X12), so that's where I buy mine.


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## Tom Struble (Mar 2, 2007)

did one using this..hard to see but it's three 1x6 with the middle piece offset 3/4'' to the edge


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## bluebird5 (Dec 13, 2010)

Cal Sustainable said:


> Here's my ceiling with 2x6 doug fir installed straight from, I do actually really hate to say, the shall-not-be-named orange store. However, it was much cheaper and better quality than what my trusty real deal lumber yard was charging and supplying. 15# above, 1 1/2" rigid foam with sleepers, then 1/2" ply, 30# felt, 30 yr roof.
> 
> If you have the benefit of time on your side I HIGHLY suggest letting the wood dry as much as possible before installing it. As you can see, those gaps. They don't really bug me too much because it's my house and I don't care, but there's a good 3/16"-1/4" between every board. Just FYI. And, no smell to speak of...


Looks great. How high are your ceilings?


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## Metro M & L (Jun 3, 2009)

Tom Struble said:


> did one using this..hard to see but it's three 1x6 with the middle piece offset 3/4'' to the edge


Jeebus, what do you think wood just grows on trees?


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## Cal Sustainable (Nov 21, 2014)

bluebird5 said:


> Looks great. How high are your ceilings?


9'6" up to about 15'5" at the ridge...


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## pappagor (Jan 29, 2008)

one thing you can do is to put a grove in the sides of the 2 x then put in 1/4 or 3/8 plywood stripes they will fill and hide all gaps


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