Replies

1. 
   Svenny | Feb 19, 2009 02:16am | #1

   I'll jump in by saying I see nothing wrong with felt for underlayment, and leave the vapor barrier question to others :-)

   John Svenson, builder,  remodeler,  NE Ohio

2. 
   DanH | Feb 19, 2009 02:38am | #2

   Felt vs housewrap is a religious issue around here, but in Mass, with conventional construction (fiberglass insulated frame construction), there should be some sort of VB on the inside.  This can be craft faced FG (if the edges are lapped), plastic sheeting, or foil-backed drywall, or one or two other schemes.

   The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness. -John Kenneth Galbraith
3. 
   Dinosaur | Feb 19, 2009 02:49am | #3

   There are probably a helluva lot more houses out there with felt as an exterior 'house-wrap' than there are with Tyvek¯ or Typar¯. And most of them have been around a fair bit longer than have the newer ones with the higher-tech wraps. That fact right there is something to think about seriously before jumping on the 'thoroughly-modern-Millie' bandwagon and insisting on some whiz-bang synthetic just because it's 'modern'.

   Felt has a long and honourable history in use as a wind/water barrier under siding, and there is no good reason not to use it today other than convenience. Synthetic housewraps come in 9'-wide x 100'-long rolls, and thus many houses can literally be 'wrapped' in one pass, and then have the openings cut out later. So it goes on faster than felt, which is either 3' or 1 meter wide and must be 'shingled' on from the bottom up, usually in three courses.

   Finally, a roll of Tyvek¯ will cover 900SF for appx $125 (I'm not sure of the exact cost; it's been a while since I used it); a roll of 15# felt costs me $18.95 and will cover 450SF. I'm sure you can do the arithmatic necessary to resolve that aspect of the question yourself....

   As to the lack of a vapour barrier to allow the house to breathe, there's a difference between allowing the house to breathe properly and allowing all the humidity generated by human activity inside the house to pass unhindered into the wall cavities.

   I agree wholeheartedly with the philosophy of not sealing the house up like a plastic baggie, but I use a vapour barrier even so. To do this, I use aluminumised kraft paper VB instead of polyethylene sheeting in all areas except bathrooms. The kraft-paper VB works quite well to limit moisture penetration, but still allows enough air movement through the wall cavity to avoid the formation of many of the moulds and fungi that characterise what is known as 'sick-house syndrome'.

   Dinosaur

   How now, Mighty Sauron, that thou art not brought
   low by this? For thine evil pales before that which
   foolish men call Justice....
   

   

4. 
   Clewless1 | Feb 19, 2009 03:54am | #4

   I just finished my new house and consciously chose felt over wrap. There is nothing wrong with it. It is not as 'consistent' if you are trying to create a better air barrier, but it is still just fine.

   Vapor barrier on the interior has often been done in the NW using a vapor barrier paint (not much different than many 'standard' paints). You do need a vapor retarder of some sort. Energy codes often have required a vapor retarder with a 1.0 max perm rating (I think I got that right). The paint has been popular because it is fairly continuous, doesn't get holes in it and you don't have the 'problems' w/ e.g. poly (many sheetrockers don't like it). Vapor retarder is simply a very good idea. If he doesn't use one, I hope he ventilates well or as you say, he's asking for trouble.

5. 
   RedfordHenry | Feb 19, 2009 06:18am | #5

   Felt is fine, so is Tyvek, pick one you like and just pay attention to the details. 

   If he's rocking and painting, he'll probably be just fine without a "VB".  Conventional building science suggests it is useful in very cold climates, but in MA, you can do without.

    

1. 
   stevenplane | Feb 19, 2009 06:39am | #6

   This is the guy to check out on the vapor barrier question:

   http://www.josephlstiburek.com/index.html

   I'm guessing he would say no, assuming of course there is a properly sized heat and air system installed that would handle humidity.

6. 
   klhoush | Feb 19, 2009 07:08am | #7

   Sounds like the walls can dry to the interior or the exterior. Of course, the performance of the insulation will be compromised if there's no air barrier.

   A low tech builder is probably better off using low tech products.

    Call me old fashioned or call me,

   Old B%sta%d!  

1. 
   pete123 | Feb 19, 2009 07:38am | #8

   Here in AK had kraft faced batts up for much of a winter with no interior VB. It was T1-11 with tar paper underneath then the fiberglass batts. Pulled back a couple batts when it was about ten below and lots of ice had built up on the cold side. VB is up now with plenty of black death to seal. I am no expert just sharing my experience.

1. 
   klhoush | Feb 19, 2009 07:56am | #9

   Yeah, in extreme climates you have to control the humidity inside the wall. They are in MA, hopefully in the banana belt.

2. 
   Clewless1 | Feb 19, 2009 06:18pm | #15

   Kraft faced batts are a vapor retarder (assuming proper installation, which admitedly can be difficult). The other part of moisture control is proper/controlled ventilation (i.e. exhaust fans in bathrooms, etc.).

   Old houses relied on leaky construction to control moisture. Now w/ energy concerns, we have to change our approach a little. Controlled leaks (i.e. fans) are better than uncontrolled leaks (wind blowing through my house), from an energy perspective. Ventilate when moisture production is high (i.e. when taking showers or when the space is occupied heavily).

7. 
   davidmeiland | Feb 19, 2009 08:03am | #10

   Google for 'airtight drywall" and consider using the details shown. Preventing air infiltration into the wall is a good idea. More moisture is moved by air than by vapor diffusion. As mentioned above, the dew point during the winter may very well be on the inside of your sheathing, and you may get frost forming there is you don't control the interior humidity in the house and the amount of air moving into the walls. Plastic sheeting gets very mixed reviews but apparently it's the right idea in some climates. If everyone is doing it where you are then you might consider it.

8. 
   Scott | Feb 19, 2009 09:25am | #11

   It's clear that he doesn't understand the purpose of the VB, which is to stop airborne moisture (from cooking, tubs and showers, respiration, etc.) from migrating outward through the drywall and insulation. Once the moisture gets this far, at least in Winter, it is likely to land on cold sheathing and framing, and condense. It can also condense inside the outermost insulation.

   Condensation is bad; after a while it can cause mold and rot.

   VBs are a simple concept, but probably one of the most common misunderstandings. I once had an insulation guy tell me that the plastic VB boots that go behind electrical boxes were to make sure that rainwater from outside didn't get into the box!

   Scott.

   
   

   ---

   Edited 2/19/2009 1:30 am by Scott

9. 
   Piffin | Feb 19, 2009 02:04pm | #12

   Will this house have AC running in summer?

    

    

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   Taunton University of Knowledge FHB Campus at Breaktime.
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1. 
   maguire | Feb 19, 2009 04:34pm | #13

   No it won't

1. 
   marv | Feb 19, 2009 04:46pm | #14

   I see no problem with his approach.  Actually, the sheathing and the tar paper are both "vapor retarders" and will slow down migration of moisture.  Vapor can migrate in and out of the house.  Millions of older homes were built this way and do not have mold problems.

   I think this is a better than sandwitching moisture between a plastic vb and the vapor retarding sheathing.

   You get out of life what you put into it......minus taxes.

   Marv

   Edited 2/19/2009 8:48 am by Marv

10. 
    frammer52 | Feb 19, 2009 06:27pm | #16

    We live in relatively the same climate as you.  Builders have stopped using VB at all.  I can't remember the reasoning, but it sounds like the building will be fine.

11. FHB Editor
    JFink | Feb 20, 2009 11:44pm | #17

    I'd say your friend is fine on both counts - I prefer felt paper myself, and I'm told by scientists that are smarter than I am that vapor barriers are quickly becoming a thing of the past.

    Justin Fink - FHB Editorial

1. 
   maguire | Feb 21, 2009 03:25am | #18

   Hey Guys . Thank you to all that responded and respect all of your ideas . Ya know maybe people are leaning towards no vapor barriers but I too have pulled back walls with no vapor barrier and they were loaded with mold In my own house , I insulated my third floor attic and got sidetracked right before the winter and did not get to finish the plastic vapor barrier and I went half the winter without it finished and when I pulled back the Insulation without vapor barrier it was all mold , so much that I wouldn't let my kids up there and yet then I decided to pull back vapor barrier and check those bays and they were like brand new so I have a to disagree with any one who says we don't need a vapor barrier in cold climates. Now these walls were not rocked and maybe I got more of an extreme result. Warm air condensates when it hits cold, Warm air holds alot more humidity than cold. Its like the old storm windows or single pane windows , they will always condensate on the warm side . Anyways We are insulating with the kraft faced insulation in his house. So lets see what happens. But again thanks for all your input, as much as I am sure on my beliefs, I wanted to hear what other builders thought , thats how we learn and the day we think we know everything is the day we should hang up the belt and call it the day!

   Edited 2/20/2009 9:10 pm ET by maguire

2. 
   fingersandtoes | Feb 21, 2009 04:43am | #20

   Surely you mean conventional poly vapour barriers? I haven't seen anyone sensible who is arguing that you don't need some alternative way to stop indoor moisture laden air from moving through the wall and reaching the dew point at a rate that the wall's ability to diffuse it can't handle.

   A lot of the comments seem to assume that because conventional vapor barriers are being abandoned that they were not necessary, whereas in fact they are just being replaced by other approaches. Vapour barriers came into widespread use in response to the building envelope problems encountered when insulation was added to walls with no thought to the consequences. The last thing we need is a return to the mold and structural damage seen when this first happened in the early 80s.

1. 
   Clewless1 | Feb 24, 2009 09:26am | #23

   I agree ... we are simply opting for an alternative [vapor barriers] that may be somewhat less conventional, well known, or widely used. Lots of ways to do it. Some climates or construction conditions may be a little more 'forgiving'. LOTS of factors come into play (wind, exterior construction, ventilation fans, etc).

   While we can make general statements about what is good/bad ... others will point out lousy conditions that pose no problems and declare that no vapor retarder is required. What seemingly works in one situation doesn't work at all in others. It's the complexity of the situation that makes the differences.

12. 
    Waters | Feb 21, 2009 04:36am | #19

    #1 Felt has shown to be a very effective housewrap.  Most guys don't like it b/c it's a pain to install.  It rips easily, must be folded carefully...

    #2 There are many interior paints these days that qualify as VB's.

    My humble opinion.

     

1. 
   maguire | Feb 21, 2009 05:02am | #21

   And a good one at that Waters , I'll look in to that !

1. 
   Waters | Feb 21, 2009 05:23am | #22

   I think this is the article in some obscure magazine that I recall...

   http://www.taunton.com/finehomebuilding/how-to/articles/making-sense-of-housewraps.aspx