Rough cut siding

[starmac]

I have some questions about siding, both beveled siding and board and batten.
All I have sawn is white spruce, which is very forgiving and easy to work with compared to a lot of different species from what I have read.
I have read that many of you get by fine taking it off the mill and nailing it up.
My question is, everything here is wrapped with a vapor barrier after the walles are up and before any type of siding, The most used by far around here is tyvec. Can a guy get by siding with green siding on top of the tyvec?ith the board and battens, you would have the thickness of the furring seperating it, would you have to dry the furring down some before nailing it up?
Beveled siding would be basically up against the vapor barrier, will weird or bad things happen with green lumber exposed to air on one side, but not the other?
Just trying to get a game plan this winter and do some building this spring, or more likely summer.
I do not have a moisture meter, but the little I cut last summer at 1 in thick, seemed to air dry pretty quick just from the feel of it.

[beenthere]

Note that Tyvek isn't a vapor barrier. Wind and moisture yes, but vapor no. Tyvek and the like is designed to let vapor pass. The vapor barrier, like poly film (Visqueen) should be on the warm side of the insulation to restrict house moisture from getting into the insulation and condensing.

Now with warm climates where air conditioners keep the inside colder than outside, then the trend has been to not add that vapor barrier on the living side of the insulation. But in Alaska, best have it on the inside.

Your green siding will prolly freeze dry after putting it up green. ;)

So I'd say yes, put up the siding over the Tyvek as it is not a vapor barrier.

[GeneWengert-WoodDoc]

In AK, you do indeed need a vapor barrier on the inside and Tyvek on the outside if you want to be energy efficient and more comfortable when the wind is blowing.

The "wet" siding is fine, but allow for shrinkage initially and movement when in use.  This is done, in part, by overlapping and by the nailing of just one edge.  It is oftentimes suggested that the ends of the pieces be coating with a moisture resistant coating to prevent water adsorption at the ends.  Fasteners need to be treated so they will not rust and stain the siding should they get wet.  The Internet has many good videos on installation.

Appreciate that with plywood corner bracing and OSB sheathing, siding is decorative and has little structural benefit.

[starmac]

That is what I wanted to hear.
I did not realize that tyvec was not a vapor barrier though.

[jueston]

things like poly and tyvek are given a perm rating based on how much water vapor can get through it.

6-mil poly is considered a class 1 vapor retarder(also called a vapor barrier) and has a perm rating of something like .1

15# felt paper has a perm rating of around 8

dupont tyvek housewrap has a perm rating of 58

the idea is that you want water vapor to move to the outside not the inside. so you want a high perm rating on the outside and a low perm rating on the inside.

lots of building scientists these days think we should have much higher perm ratings on the interior and exterior so that our houses can breath, some are building experimental houses with osb on the interier(under the drywall) and fiber board on the outside.

but all of this only matters if your siding is effectively keeping water outside the walls, the house wrap is not intended to have water siting against it regularly. its full of nail holes and seams and will leak.

[GeneWengert-WoodDoc]

The statement "the idea is that you want water vapor to move to the outside not the inside. so you want a high perm rating on the outside and a low perm rating on the inside." applies only to homes and buildings in the northern half of the central and eastern U.S.  In areas where air conditioning is used, vapor barriers would possibly be better on the outside (warm side), but in fact are seldom used.

The whole idea is to prevent moisture from the living environment (which has more pounds of water per cubic foot) inside the house (especially in the wintertime in cold climates) from getting into the wall, cooling off enough to reach the dew point and then condensing inside the wall.  So, in addition tot he interior vapor barrier, the exterior is designed to easily pass any moisture that accidentally (hole cut for plumbing or electric for example) gets into the wall to the outside.

[starmac]

I do not know what it is called, but my daughters house has a system that catches water inside the walls, and periodicaly drains it. You can actually hear it when it trips and drains the water.

[beenthere]

Interesting. Would you find out more about that system for us, please?

[starmac]

I will at least find out what it is called, or try to. lol
A guy I work with ocassionally mentioned his son house has the same system, or one very like it here in Fairbanks, so I know there is at least more than one. lol

[GeneWengert-WoodDoc]

I know that we have such systems for a basement...French drains and sump pumps...especially in below grade walls.  I am looking forward to more info if this system is in a house wall above the ground.

[BigJim2185]

If you go with beveled siding, consider installing vertical 1x4 furring strips over your water resistive barrier (tyvek) and nailing the siding to those, with a screen or vent at the top and bottom - there are a number of commercially available vent products for this purpose.  This creates a rain screen behind your siding, allowing any moisture that gets back there to drain or evaporate much more quickly.  It also gives your wall assembly more potential to dry to the exterior, and will extend the life of wood siding by allowing airflow across the back of it to minimize moisture retention. Good luck with your project.

[starmac]

BigJim, I wondered about that, and sure couldn't see any reason it would hurt anything, other than using a few more boards.