fan-fold or Tyvec?

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  #1  
Old 09-02-02, 11:11 AM
bez
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fan-fold or Tyvec?

I'll soon be siding over existing narrow cedar siding on my 100 year old house. I'll be using a wider masonite painted product. The question is, should I install fan-fold prior to new siding or should I go w/ a wrap like Tyvec? I've been told that Tyvec breathes and the fan-fold doesn't. Yet the fan-fold has an insulating quality which Tyvec doesn't. I'd do both, but there's no point in that if one breathes and the other doesn't. Whaddya think?
 
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  #2  
Old 09-02-02, 12:16 PM
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The following to taken from this site http://www.eren.doe.gov/consumerinfo/refbriefs/bd4.html from the air barrier topic.

In wet climates house wrap sometimes reacts poorly with certain kinds of wood siding. Lignin (a natural occurring substance in many species of wood) is water-soluble and acts as a detergent. Like all detergents, it decreases surface tension and so destroys the house wrap's ability to repel water. Field research has shown that wood lignin makes it easier for liquid water to pass into the wall. Certain types of wood siding like redwood, cedar, and manufactured hardboard siding seem to accelerate the problem. To avoid this problem, carefully attach heavy building paper (30 pound asphalt impregnated) to the walls as a substitute for house warp or install felt-paper over the house wrap as a water repellent surface that is unaffected by wood lignin
 
  #3  
Old 09-02-02, 12:30 PM
rbisys
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Geetings,

You might also consider perforated radiant barrier(RB) insulation.
It acts as an exterior insulation and helps reduce the condensation in the bulk insulation. You can attach to the wall and then cover or if the siding material is strong enough you can furr the walls with 3/8" osb strips and get 2 reflaective air spaces.

You might also want to consider installing a RB in the attic. It can reduce the summer loads up tp 30%.

When I did siding work this combo usually reduce the total utility bills 40% or more.

Thank you for considering my opinion.
 
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Old 09-02-02, 02:18 PM
bez
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thanks, gentlemen, for your insights. The existing siding was put over building paper or felt paper, and the over the years has lost its effectiveness to the point that high winds will drive rain up under the narrow siding and THROUGH the bldg. walls. That's the reason for my re-siding project. Will either of the procedures you fellas describe be more effective in preventing recurrence of that problem? I still don't know about the Tyvec vs. wrap controversy. Is one breatheable and the other not? Is one preferable to the other? Will the radiant heat barrier breathe and yet prevent water entering the walls?

Incidentally, the re-siding project will be followed by removal of a couple plaster/lathe interior walls, along with insulation, and then re-insulation and drywall installation. The entry of moisture due to driving rain has made that necessary, I'm afraid. I want to get the siding project done first, to prevent worsening of the situation.
 
  #5  
Old 09-02-02, 09:53 PM
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On the site that I gave you in the previous post also discusses Perm Ratings. With Tyvek or other types of house wraps, they are specifically designed to repel water (liquid) as a drainage plane and at the same time because of its high perm rating, allows moisture vapor to pass through it so moisture does not get trapped inside the walls. House wraps are specifically designed to replace building felt paper.

What makes house wraps a better product than building felt is how it is installed. Building felt is put on in rows and house wraps come in large sheets and the joints are taped.

Since you are using a manufactured siding, if Lignin is in this product, it will degrade the house wrap and allow water (liquid) to enter the wall. What the U. S. Dept. of Energy site recommends to avoid this is to apply building felt over the tyvek or house wrap when using those types of siding. Though this may be redundant, the advantages of a house wrap clearly justifies the installation. Considering your own personal experience concerning moisture problems in walls.

Tyvek is a name of a product and is a house wrap. With wind driven rain, Tyvek or house wraps were design because of that. It is primarily how it is installed that corrects that problem. The large sheets and taped seams prohibit water from being wind driven pass it.
 
  #6  
Old 09-03-02, 11:11 AM
bez
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OK, I understand about the housewrap. The lignin was a new one for me, but I think I get that picture too. Now how about the fan-fold product. Water repelling? Insulating? breathing? Use w/ or w/o housewrap?
 
  #7  
Old 09-03-02, 06:20 PM
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Is the fan-fold product you are referring to made of styrofoam?
 
  #8  
Old 09-04-02, 09:39 AM
bez
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I'm only familiar w/ 1/4" styrofoam which is advertised as "used when siding over existing siding".

Are their optional materials in fan-fold? Characteristics?
 
  #9  
Old 09-04-02, 12:00 PM
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I was not absolutely sure by what you meant by fan-fold, but the only type I know of is made of styrofoam. If this fan-fold is recommended to use with the siding you intend to install, then I would suggest you use it with the Tyvek or any other type of house wrap. Naturally the Tyvek should be installed first. It is only prudent, you check with the manufacturer of the siding to see if there are any concerns.

The fan-fold, if specifically designed for siding will repel water (liquid) but I don't think it will do a very good job with wind driven rain. The Tyvek will. Also this type of styrofoam will have a high perm rating to avoid moisture (vapor) being trapped in the walls.
 
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Old 09-04-02, 12:05 PM
bez
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You say the styrofoam has a high perm rating and that it therefore would prevent moisture from being trapped in the walls. Does that mean it breathes like the Tyvec does?
 
  #11  
Old 09-04-02, 12:14 PM
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Yes, the Tyvek or similar house wraps will probably have about the same perm rating as the styrofoam when designed for use under siding.
 
  #12  
Old 09-04-02, 01:26 PM
bez
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thanks, fellas, for your help. My q's are answered, and now I just have to schedule and do the work! End of thread. Thanks again!
-bez-
 
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