Directions on Rainscreen

[NM_Shooter]

My kind of article... simple words, pretty pictures.

http://www.greenhomebuilding.com/pdf/RainScreen.pdf

-f-

[FrankInWI]

WOW!!!  Extreemly usfull pictures! 

[MountainDon]

Good one Frank! What I've been thinking of.

[Mandres]

Great article, Fine Homebuilding always has very useful information.  Does anyone have a subscription to their online depository?  Is it worth the cost?

One thing I'm unclear about from the article: do the furring strips run all the way down to the foundation, or do they stop at the top edge of the plastic vent? 

[glenn kangiser]

Good article, Frank.

As I have seen it the plastic vent is to exclude bugs etc and it would run continuous across the bottom with the furring strips stopping at the top of it.

[NM_Shooter]

I was trying to figure out what was meant by rain screen construction and googled this up.  My plan is to use hardi-planks, and to not use a water table base trim but to lap the planks all the way down. 

I'm not sure how far to space the furring strips or what sort of fasteners to secure the hardi planks to the strips.  I am in a high wind area.

I'd like to just use galvanized nails, but have not tried nailing those through hardi panel using my air nailer.  I don't want to overdrive them and end up blowing chunks out of the panel.  I may drive them short and then finish them off by hand.

I also noticed in the document that they indicated that it was best to shim the windows a bit.  Is this done by nailing a perimeter of the furring material around the window before installing the window?

Thanks,

frank

[MountainDon]

I also noticed in the document that they indicated that it was best to shim the windows a bit.  Is this done by nailing a perimeter of the furring material around the window before installing the window?

I am not positive on this, but that does seem totally logical, otherwise the windows would be recessed by that amount by the time the wall was completed.


James Hardie recommends a maximum nail spacing of 24" for securing their plank product. It may be face nailed on the lower edge where the nails will be visible or blind nailed along the upper edge with the nails hidden by the next row. In either method a minimum overlap of 1 1/4" is stated, with the nails 3/4 to 1 inch from the plank edge. When blind nailing roofing nails may be used... less chance of push through I guess with the larger head. Bugle head screws may also be used.

Ring shank nails would provide better grip than plain. I can get them in galv for my nailer. Hardie suggests 6D galv or stainless. Even using an air nailer you'll be doing a lot of hand hammering to set the heads "just so".

I wonder, with using a 3/8 inch furring strip, should 8D nails be used to make up for that 3/8 inch extra thickness behind the hardi-plank? Or would the extra nail diameter be caue for potential trouble?

The James Hardie website has installation info sheets available for download.  Click on the "View Installation Instructions" link.

[MikeT]

Thanks for this article.  Perfect timing as I am currently working on this part of the project.

Question: I will definitely do this for the T-111 I am using on the backside and below deck portions of the house.  But on the upper parts of the house I am using cedar shingles.  Am I correct that these have enough spacing behind them that this would not  be necessary?

Thanks again,
Mike

[glenn kangiser]

Mike, if using felt, I have never seen a house on the coast with problems using shingles, and it agrees with what PEG recently posted if I recall correctly.  In other words - rain screen not necessary with shingles - they will drain fine over felt.  I wouldn't put shingles over housewrap as the oils in the cedar will render the housewrap useless - like putting a wet rag under your shingles.

[MikeT]

Thanks, Glenn.  I am indeed using felt--30#, kind of wrinkled.  I am using 3" trim around my edges and 6" (nominal) on the corners.  Would you put some kind of rainscreen on the  backside of these or would you kerf the backs of the trim boards? Or both or neither?

mt

[glenn kangiser]

I wouldn't worry about it myself, as it is not real wide - the felt will bring the moisture out.  PEG would know better than I.

New number 30 felt is lighter than the old 30#.  Both may be available.  PEG like 15# on the walls.

[MountainDon]

PEG like 15# on the walls.

What PEG said about #30 being difficult to handle around corners and having the tendency to tear under the pull of it's own weight is correct. Been there and done both.    We used #15 on the current cabin walls. #30 for the roof.


I've read somewhere and forgotten where, that building paper/felt has changed and is no longer as heavy as it used to be. This changed during the 1980's. It used to be rated by how much it weighed per 100 sq. ft. as in being referred to 30#, 15# etc. (the # symbol behind the numerals to signify pounds) Then back in the Carter days and the oil embargo, the product was reformulated with less asphalt. The labeling system was changing to todays #30, #15, etc. (the # symbol before the numerals to signify number not pounds. #30 is apparently closer to the old 15#. It's still referred to as 30 pound, 15 pound, but that is technically incorrect. Note that todays product labels clearly have the # symbol before the number.

[glenn kangiser]

Within the last 6 years or so I have still seen both #30 and 30# -- I know because I was wondering what the heck was going on a couple years ago.  The old style was twice as thick as the new.

[MikeT]

For the furring strips between the tar paper and the siding, the article implies using 3/8" ply.  Would 1/4" or 3/8" cedar strips work as well?  I can't imagine this would be too much of an issue, but I could be missing something.

Does thickness matter?  Is there a minimum thickness?

mt

[TheWire]

I'm using 1/2 PT plywood ripped in to about 2" wide strips for the battens on my rain screen.  Even the 1/2" breaks near knots with slight bending pressure until its nailed up.  Maybe I got some cheap PT plywood, but I wouldn't use 3/8" plywood.  I think 2"x1/2" or smaller sawn lumber would have a tendency to split from the nails holding to the building and the nails holding the siding.

[ScottA]

Gap needs to be atleast 3/8" to prevent wicking. I'm using 1x2" cedar but any rot resistant wood should be ok.