fanfold/tyvek


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Old 04-20-05, 11:30 AM
pipefitterlu42
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fanfold/tyvek

I'm going to install new vinyl siding. I have good osb under the old aluminum siding. Should i use fanfold or tyvek or niether? It is suggested that i have some sort of moisture barrier correct? Also, will tyvek let my house breath? I don't want to cause any problems. Thanks for any help.
 
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Old 04-20-05, 12:50 PM
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Tyvek is a wind/water barrier that allows your house to breath. Fanfold is insulation, 2 whole different product types. Are you interesting in waterproofing or insulating or both?
 
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Old 04-20-05, 01:36 PM
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I don't see how it could hurt (unless it ends up trapping moisture). My house just has OSB and then the vinyl. Nothing between except where the windows/doors are.
 
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Old 04-20-05, 01:43 PM
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I'd tear off the aluminum siding and install tyvek. Fanfold is pretty much worthless as insulation because it is so thin. It also not a weather resistant barrier like tyvek, no matter how much you might try to tape and seal the seams- it isn't building paper.

It's *very* important to have good building paper under vinyl siding, because water can get behind vinyl siding at every penetration. In some parts of the country (for some unknown reason) codes did not require builders to install building paper behind vinyl siding, and now people are having to pay for it. Rotton OSB, lawsuits, the works.
 
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Old 04-20-05, 02:12 PM
pipefitterlu42
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I'm mostly worried about keeping moisture away from the osb. The house has insulation in the walls so I'm not concerned with the insulating value of fanfold. I've just had so many people tell me "trust me...use fanfold". Nobody says anything about tyvek.
 
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Old 04-20-05, 03:26 PM
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The best way to keep moisture off your OSB is with Tyvek and tyvek peel and stick membranes. (straightflash flashwrap) Install new dripcaps over all your windows and doors that will be behind your tyvek. Tape all your seams with Tyvek contractor tape.

"trust me".
 
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Old 04-20-05, 04:00 PM
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I did some looking and come up with this:

From the Florida Building Codes 2004:
"1404.2 Water Resistive Barrier
A minimum of one layer of no. 15 asphalt felt, complying with astm 226 for type 1 felt, shall be attached to the sheathing, with flashing as described in section 1405.3, in such a manner as to provide a continuous water-resistive barrier behind the exterior veneer."

Just my luck, my home (built in 2004) was built using the 2001 codes, which as best I can tell, only say the seams and other openings have to be sealed.

If I had known at the time that 2004 codes were out, I probably would have insisted the home be built using the *current* codes. Which just goes to show you can't assume anything is being built with current codes!
 

Last edited by Pendragon; 04-20-05 at 04:11 PM.
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Old 04-20-05, 04:29 PM
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Pendragon,

A woman from Indiana recently posted here with the same problem, (same addendum to the building code) but in her case, the addendum to the code came out BEFORE her house was complete, so she actually has a case with the builder, general contractor, or the state inspectors who should have caught / enforced the new code. Someone ought to pay for mistakes like this and it shouldn't be the homeowner!

In my opinion, no self-respecting installer / contractor would ever put up any type of siding without building paper, no matter what the codes say. It's just common sense. Unfortunately, some people in the business were born without any.
 
 

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