# Vapor Barrier under solid hardwood - Always?



## Cascade Builder

Hi guys,

I say yes. I am working with a floor guy who says he never installs a vapor barrier under the floor on the 2nd floor of a house???? I say always install it, no matter what. I had him take up maybe 50 sq ft and start over. The product is a solid pre finished red oak. I called the manufacturer and they said always install a vapor barrier, not matter what floor, and it would not be warranted if not.

So I just wanted to see what all you other guys thought on the matter.

Thanks ahead of time.


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## wizendwizard

Cascade Builder said:


> Hi guys,
> 
> I say yes. I am working with a floor guy who says he never installs a vapor barrier under the floor on the 2nd floor of a house???? I say always install it, no matter what. I had him take up maybe 50 sq ft and start over. The product is a solid pre finished red oak. *I called the manufacturer and they said always install a vapor barrier, not matter what floor, and it would not be warranted if not.*
> 
> So I just wanted to see what all you other guys thought on the matter.
> 
> Thanks ahead of time.


 This answered itself!


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## Cascade Builder

That's what I think. He seemed surprised that I even called the manufacturer, which might show some of his inexperience. Other than that, it just seems dumb not too install it, even if the manufacturer doesn't require it for warranty.

It also seems bad to have a wood to wood connection for a floor. Seems like you would be asking for squeaks in the future.

He's back on track now. At least he wasn't almost done when I caught it.


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## mics_54

Heck yeah...you don't want that first floor water vapor comin through the floor!


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## the big 12 inch

The wood floor manufacture is obviously in bed with the vapor barrier guy...Total scam...:thumbup:


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## MacRoadie

Yeah, I'd like to hear a practical explanation for that one. I've NEVER heard of anyone using a "vapor barrier" on anything but a concrete slab. Rosin paper yes, visqueen no.


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## mics_54

Floor sheathing installed correctly"used" to meet the astm perm rating requirements for "vapor barrier" ...not sure if it still does...and I don't feel like researching it.


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## Floordude

You absolutely DO NOT use a vapor barrier over a wood substrate, under a wood floor.
Asphalt felt, or rosin paper as a slip sheet, when on the second story of the residence.
You don't want wood to wood.

Moisture barriers are for going over concrete, or to cover the top soil in a crawl space. Anything else promotes dry rot.


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## Cdat

Never heard of using vapor barrier until today. Imagine that?


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## Cascade Builder

Sorry for the confusion. Yes I mean an asphalt felt ( always prefer 30 lb myself, helps dampen sound ), or a rosin paper. Not a visqueen, which a vapor barrier is also. OR am I incorrect in calling the use of asphalt felt under a floor as a vapor barrier? That is part of it's job, blocking moisture right?

It seems like the general idea is to have the wood sealed on both sides. The finish seals it from the top, and the 30lb felt from the bottom. Wood to wood always seems like a bad idea. 

Good to know what everyone else thinks.


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## wizendwizard

Cascade Builder said:


> Sorry for the confusion. Yes I mean an asphalt felt ( always prefer 30 lb myself, helps dampen sound ), or a rosin paper. Not a visqueen, which a vapor barrier is also. OR am I incorrect in calling the use of asphalt felt under a floor as a vapor barrier? That is part of it's job, blocking moisture right?
> 
> It seems like the general idea is to have the wood sealed on both sides. The finish seals it from the top, and the 30lb felt from the bottom. Wood to wood always seems like a bad idea.
> 
> Good to know what everyone else thinks.


 I understood what you meant. To use their words, paper materials such as felt or rosin are whats used. Any plastics would trap water or moisture under the wood, not good. Clarified? good!


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## neolitic

Red rosin paper worked just fine
for a hundred years.
How much of a vapor barrier do you 
have after you drive thousands 
of nails through it?


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## Cdat

I never knew it was meant to be a barrier. When I have to take up flooring to place inlay, the paper comes up to. I can't imagine glueing to a piece of paper would accomplish much. Maybe I'm doing it wrong? Haven't had one loosen yet, so maybe I'm on to something.


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## neolitic

More than one old timer told me
that it was mostly there to minimize
squeaks and groans between the
oak and the sub floor.


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## Cdat

That is the only reason I can figure out too. Anything else seems like a bs line from the industry (flooring), to make an extra buck.


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## neolitic

Yeah, the old timers didn't know 
how to say, "decoupling membrane."
Could have charged extra for the rosin paper
that way. :laughing:


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## Floordude

Asphalt saturated felt, is not a moisture barrier, by any means.

It retards the moisture, but it is not a barrier. It slows the moisture transfer, but does not eliminate it like a barrier, with a high perm rating.
Moisture retarder.

I have pulled up old wood flooring, that could no longer be sanded and it have news paper from 1937, between the 45º plank subfloor and the wood flooring.


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## WNYcarpenter

I'm with Neo and Cdat...My understanding of paper under the floor was for squeeks...we don't overlap, or really do a very neat job (per se) putting down the paper...like mentionioned earlier... not to install wood on wood.

I also like 30# felt over rosin paper....rosin paper tears so easily.


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## StinkyTheGrump

So then Tyvek would not be a good thing to use for a barrier right? Local flooring supplier recommended this for some reason..


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## WNYcarpenter

StinkyTheGrump said:


> So then Tyvek would not be a good thing to use for a barrier right? Local flooring supplier recommended this for some reason..


Tyvek would probably be a great product to use, but I think cost is the issue....I've was led to believe that the paper was for squeeks more than anything unless you're dealing with a concete slab...

The only situation I can think that would require a vapor barier would be directly over a bathroom....

I don't know....I know that we nail more than just into floor joists, so what difference does it make anyway?


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## lawndart

Floormasta78 said:


> Second floor moisture barrier..
> 
> Always !
> Always !!


The moisture barrier looks great! However, it looks like your nailing into a particle board subfloor. Looks like you'll be back replacing the loose floor soon, but atleast it didn't buckle from moisture.

What were your moisture readings in the subfloor and product, before you began installation?

What were the RH readings in the rooms you installed?

Did the customer have a HVAC system with a humidifier built in? What about an air conditioner, or de-humidifier for the humid summer months?

How long did you let the flooring acclimate in the customers home before installation?

What were the conditions like in the storage/warehouse, that the material was being stored in before it was delivered to your customers home?

THIS LOOKS LIKE PARTICLE BOARD TO ME.


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## ryanshull

The moisture barrier is there to seperate the subfloor and hardwood because they have different absorption and expansion rates relative to the ambient humidity and you don't want the moisture to be wicking from one to the other.

Whether it be felt or one of the newer engineered products, it has the same purpose. 

When moisture is wicked between the sub and finished floor, the different expansion rates will cause slight seperation in the joints-growing over time. So with the barrior, the entire finished floor expands/contracts at one rate while the subfloor expands/ contracts at a slightly different rate.

So, yes a moisture barrior will be needed regardless of what level it is in the building.


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## ryanshull

ryanshull said:


> The moisture barrier is there to seperate the subfloor and hardwood because they have different absorption and expansion rates relative to the ambient humidity and you don't want the moisture to be wicking from one to the other.
> 
> Whether it be felt or one of the newer engineered products, it has the same purpose.
> 
> When moisture is wicked between the sub and finished floor, the different expansion rates will cause slight seperation in the joints-growing over time. So with the barrior, the entire finished floor expands/contracts at one rate while the subfloor expands/ contracts at a slightly different rate.
> 
> So, yes a moisture barrior will be needed regardless of what level it is in the building.


I am pretty sure I learned that by simply reading the side of the box on some hardwood.


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## Floormasta78

I used power cleats, the goods was there a month, inside the master closet in this same bedroom. and I did have a Humidor because I was smoking a Cuban cigar while I installed the flooring. The last job I did for this homeowner was exactly the same same way 5 years ago and that's why I was called again after working on 12 homes built the same way, not a single repair or failure. I'm too good to fail. I'm 100 times better than you. You question yourself too much to have the natural skills to do something based on your expertise .keep up the good job in reading instructions. I'll keep doing what I do best and that's be 100 times better than you. 

Haha ! 
I love flooring book worms. Send me a private message and I'll give you me secrets. You could use them .


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## Floormasta78

Lawndart , you sure you want to question my skills. ?

I think you need to worry more about:

Ad design 
Building your site
Cleaning ladies
Using service magic
Looking for SUB CONTRACTORS 

AND MOST IMPORTANT


PAY YOUR SUBS AND DON'T CHEAT THEM OUT THEIR MONEY 


SO THEY DON'T WORK FOR YOUR COMPETITION AND TAKE YOUR ACCOUNTS. 

sounds like you got too much to worry about to question my skills and read me a book about things you probably you ONLY read about and have no on hands experience on. 

You are a funny guy.


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## ryanshull

I take it you two know eachother........ Ouch


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## lawndart

Floormasta78 said:


> I used power cleats, the goods was there a month, inside the master closet in this same bedroom. and I did have a Humidor because I was smoking a Cuban cigar while I installed the flooring. The last job I did for this homeowner was exactly the same same way 5 years ago and that's why I was called again after working on 12 homes built the same way, not a single repair or failure. I'm too good to fail. I'm 100 times better than you. You question yourself too much to have the natural skills to do something based on your expertise .keep up the good job in reading instructions. I'll keep doing what I do best and that's be 100 times better than you.
> 
> Haha !
> I love flooring book worms. Send me a private message and I'll give you me secrets. You could use them .


Flooring book worm? These are the answers you should have documented on every flooring project. The manufacturers require it.

Most people learn how to cover their own ass, as they grow, judging by your response, it looks to me your like 98% of the other floor layers around here. 

Hack and wack away if you like, but the first time a customer calls you on it, you better have the answers to the questions I asked above, or you'll be buying a new floor, and refunding the labor.

Any good installer will take the time to read the NWFA, and manufacturers installation guidelines to avoid making installation errors. I suggest you read "what is an acceptable subfloor" Good luck sir.


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## adamsb

Hey Lawndart, looks like Oriented strand board to me. Totally different than particle board. Its a great substrate for wood floors.


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## Greg from K/W

Wow Simple fact it that its not used for a vapour barrier its used to let the hardwood slip over the sub floor. That way you don't have the hard wood giving off loud snaps while it expands and contracts over the season. Squeaks are from loosening nails and the wood moving on them. 

Forget the vapour garbage and recognize its the proper way to install the stuff. Hell I learned that in my first set of carpentry courses for my apprenticeship.


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## Floormasta78

What makes you think this is particle board. This builder knows better than to use PARTICLE BOARD to build a 2million dollar home. 

You need to focus your computer


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## Inner10

Floormasta78 said:


> What makes you think this is particle board. This builder knows better than to use PARTICLE BOARD to build a 2million dollar home.
> 
> You need to focus your computer


I don't think he knows what particle board is...


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## Floormasta78

Lol


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## adamsb

Yeah, he don't know. He was just trying to let you know everything he learned on have computer about installing floors. Relative humidity, humidifiers, dehumidifiers, documentation of what the wood is pulling before installations, etc.. We sand floors from early 1900's into the 1950's when wood is all they put down and their never buckled or peaked. Lots of them are straight to the floor joists too.


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## Floormasta78

Ooohhhhhh man !


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## pinwheel

Damn, you boys are reminding me of the bullchit reality shows on TV. Lifes too short for all the drama.


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## lawndart

Inner10 said:


> I don't think he knows what particle board is...


I know the difference between particle board OSB, and CDX. It looks like particle/pressed board over here.

OSB is a suitable subfloor for nail down installations, but I've seen and heard many in our trade recommend against using it.


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## ohiohomedoctor

Have you seen DryPly? Its like whats great about advatech in a cdx panel..


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## Floormasta78

Goggle in it.... Please wait.....




Loading .............


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## ohiohomedoctor

Zzzzzz...


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## Hoof Hearted

Cascade Builder said:


> Hi guys,
> 
> I say yes. I am working with a floor guy who says he never installs a vapor barrier under the floor on the 2nd floor of a house???? I say always install it, no matter what. I had him take up maybe 50 sq ft and start over. The product is a solid pre finished red oak. I called the manufacturer and they said always install a vapor barrier, not matter what floor, and it would not be warranted if not.
> 
> So I just wanted to see what all you other guys thought on the matter.
> 
> Thanks ahead of time.



Most people simply install felt paper on 2nd floor under hardwoods. It does more than just quiet squeaks, it helps to keep the floor held tight to the sub floor over time, and also to help prevent the passage of moisture. It is likely adequate to protect your flooring from buckling/moving in general.

However, your manufacturer has said they will not honor the floor's warranty without a "vapor barrier" So why not lay down a vapor barrier? It certainly won't hurt, and I've never heard of a vapor barrier causing dry rot to wood floors as I have heard it said.


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