T1-11 moisture barrier question " Felt/Tar Paper"

[waltsuz]

Building a cabin 20'x28'  560 sq.ft and I have it sheeted with 7/16th OSB. plan is to tar paper this and cover with T1-11. I'm currently a one man band and I can't hold the felt paper to span 28 feet to staple it up. I am thinking on wrapping it vertically with a 6 inch over lap to make this frustrating chore a bit easier. As mentioned I can't see an issue with this and I thought I'd ask for opinions. I will insure the T1 overlaps are not inline with the felt seam, is this a bad idea? Regards Walt

[ChugiakTinkerer]

It looks like a common problem that others have wrestled with.  The final comment in this thread offers a viable workaround in my mind, although 12" might be overdoing it.  The IRC requires horizontal application, so if you want it to meet code it needs to be horizontal with at least 2" overlap at horizontal seams and 6" overlap at vertical seams.  If you can live with it not meeting code, roofing cement on vertical seams would be better than just the overlap itself.

[Redoverfarm]

Building a cabin 20'x28'  560 sq.ft and I have it sheeted with 7/16th OSB. plan is to tar paper this and cover with T1-11. I'm currently a one man band and I can't hold the felt paper to span 28 feet to staple it up. I am thinking on wrapping it vertically with a 6 inch over lap to make this frustrating chore a bit easier. As mentioned I can't see an issue with this and I thought I'd ask for opinions. I will insure the T1 overlaps are not inline with the felt seam, is this a bad idea? Regards Walt

A couple of things that help is to precut your felt paper 15 or 30# in manageable lengths for the run on a side.  Trying to unroll a full roll is almost impossible working alone. Roll the run section back up so that you are not trying to wrestle a 20 or 30' piece. The weight of these will be manageable even working solo.    Measure and mark your sheeting periodically to the desired elevation where the top of the sheet will be.  Unroll the portion and tack adjusting it as you go. The second would be to invest in a hammer tacker to temporarily attach it to your sheeting.  Then if you choose to come back with button/cap nails later you can.  By design and law of gravity horizontal is your best bet.  Most rolls have a marked overlap line so if you can get the first course on fairly level then it gives a guide to go by.

[GaryT]

For what it's worth (admittedly not much)...many times when I'm called to replace wood siding on older homes that has rotted from the inside towards the outsided, when I pull the clapboards off, I find felt paper behind them, with lots of moisture on it.  If I was starting a project from scratch, I would most certainly use a modern house wrap rather than impervious, non-breathing felt paper.
Gary

[Don_P]

Hold on there... felt has a higher perm rating than housewrap unless it is saturated. I'm wondering why you are seeing them rot from the inside, air conditioning condensation, leaks... what?

Generally speaking tarpaper is "smart" compared to modern housewraps. When it is dry the wood fiber that makes up the paper shrinks and opens pores in the tar impregnation so water vapor can pass back out of the assembly. When wetted, as when the siding leaks the fibers expand and shut those pores and in that condition it is a non leaking cup, it won't pass a drop. In that scenario when the leaked liquid water has dried back to the outside, then the pores dry and open and pass any vapor inside the wall out. AC can reverse the wetted side as can a leak, or...? A modern housewrap is a better air barrier and is stronger but I'll argue with them being better at managing moisture. I do want to understand better why there is liquid water on the inside.

... on the horizon is some cool nanofiber stuff that should make really smart housewraps

FWIW, T111 is really what we call single wall material, it is sheathing and siding in one. I am concerned moisture will get trapped between panels and cause rot. Is there a manufacturer detail of this?

[ChugiakTinkerer]

Redover's comment got me thinking, and while one continuous sheet of tar paper going horizontally would be ideal, there's nothing that says you can't just hang two shorter pieces for each horizontal run and just overlap the vertical seam in accordance with the 6" minimum.

Edit: Seam, no seem

[Redoverfarm]

Redover's comment got me thinking, and while one continuous sheet of tar paper going horizontally would be ideal, there's nothing that says you can't just hang two shorter pieces for each horizontal run and just overlap the vertical seam in accordance with the 6" minimum.

Edit: Seam, no seem

I would try a piece in one run.  If it doesn't work out then cut it.  The roll of one run will not be heavy.  Start at one end and nail it then unroll and nail as you go.  Just one nail in the top to keep it level until you get to the other end.  Then come back and put additional fasteners.  Repeat for course two and so forth.

[flyingvan]

Don_P  ---  Are there particular situations or applications where you would use tar paper instead of Tyvek type housewrap?  Specifically, if you were building a tiny house (200 square feet) that had all the things that produce water vapor inside, ie shower, cooking, fireplace, breathing...Would tar paper be a better choice?

[NathanS]

Tar paper is pretty cool. Plywood is similarly 'smart' in that when it start getting wet, it allows more water vapor through, and can dry more quickly than OSB.

I considered using tar paper on my house for awhile. The problem I ran in to - manufacturers of tar paper only consider it for use on roofs, so there are no manufacturer approved methods for flashing windows and doors. Because of this, it wasn't clear to me that a lot of the flashing and sheathing tapes would actually adhere to tar paper. I had trouble finding any tests on this.

Buildingsicence.com does have a window install method for tar paper:
http://buildingscience.com/documents/reports/rr-0407-installing-a-window-with-building-paper-on-osb-over-wood-frame-wall/view

This method would allow wind driven rain to get behind your water barrier. (At the jambs the tar paper goes over top the flashing tape) Probably not a good idea if you get more than 20" of rain a year. If you do decide to do this, I would definitely want to use plywood instead of OSB.

In my opinion the solution to using OSB / tar paper / T-111 would be to install vertical furring strips over the tar paper to create a rainscreen, and then fasten the T-111 to that. It will allow much better drying potential. If you don't have that air gap, water that gets stuck between the OSB and T-111 is going to take a long time to dry out (by vapor diffusion) because both barriers have a low vapor permeability.


For installing tar/building paper alone.. you could put a dowel through the center of the roll with some kind of platform to hold it at the level you want, and lean that against the building and staple as you go.

[waltsuz]

I use OSB to staple the tar paper to. Rubber adhesive window and door/deck flashing sticks very well to tar paper. I attach the windows to the osb with screw flanged windows then sheet with TI. It makes a very strong sound quiet wall. The only problem I have had with any rott was the bottom edge of the T1 being too close to the ground. Knowing this is no issue anymore. T1 does take a bit of a different approach with moisture management but I love the looks of it done correctly and it will last a long time done right. The problem is that it needs maintenance every 5 years or so, a restain or paint. Kinda like washing your car, looks good again...Regards Walt

[ChugiakTinkerer]

There's some ideas kicked around in this thread:

http://forums.finehomebuilding.com/breaktime/general-discussion/hanging-tar-paper-solo

[Adam Roby]

I think the real key here is the air gap to allow whatever moisture buildup to dry.  I am not crazy about tar paper because I have seen it cause mold is many cases, admittedly mostly when applied over foundation work in the basement.  Used as a house wrap is a much better use for it, but I still think the new house wraps have their advantages... bottom line any of these will fail without adequate air movement, so furring strips are a must no matter what you wrap your house with.

[Don_P]

Don_P  ---  Are there particular situations or applications where you would use tar paper instead of Tyvek type housewrap?  Specifically, if you were building a tiny house (200 square feet) that had all the things that produce water vapor inside, ie shower, cooking, fireplace, breathing...Would tar paper be a better choice?

I have no qualms with using tarpaper in the same places you use housewrap. I think for the situation you are describing it is a better choice. I prefer to apply it as the siding is going up because it doesn't take wind well... there is one big advantage of housewrap. I've been installing cedar shingles in the gables at work. I interleave half width tarpaper with each course of shingles. The cedar is there to protect the tarpaper that is the real workhorse in that situation IMO.

[JRR]

A one-man crew could probably put up paper the traditional, horizontal, way by first installing temporary "shelves".  I can see some long timber screws, or spikes, driven into studs to support lengths of 2x's.  Tapered shims could be used to level the shelves.  And on the shelves could be stood (cut roughly to length) rolls of paper.  If the cut pieces are not too long, it should be fairly easy to unroll while nailing to sheathing.  (Or so it seems in my old head.)

[JRR]

Don_P, is that your own method or is it conventional practice?  I have thought of doing something similar, but not sure about using wooden shingles.  Are there fire-resistant cedar shingles available now?

[waltsuz]

https://s1100.photobucket.com/user/waltsuz/media/T1.jpg.html?sort=3&o=2

Here's the way I've always done this, The OSB is covered with felt paper and all windows are flashed in with rubber adhesive flashing typical. The T1 is painted on all edges inside and out on the perimeter before hung. The T1 is nailed directly to the tar paper. Before paint, the top is caulked in and the corners. It doesn't and won't leak behind the T1, at least I have never had issue with moisture rott yet. It takes a ton of paint to seal this stuff but lathered up really good it'll be 5 years before I recoat. Got one done exactly like this in the Chicago area where humidity is sometimes through the roof. I am building my house right now exactly the same way. Honestly never heard of using furring strips on this application, Regards Walt
ps, Lots of ways to do this and I enjoy hearing other ways and opinions..... 

[Don_P]

Don_P, is that your own method or is it conventional practice?  I have thought of doing something similar, but not sure about using wooden shingles.  Are there fire-resistant cedar shingles available now?

Did 13 hrs on a roof today so my brain is jello and the rest wishes it were (finished ridge at dark woohoo). I couldn't lay my hands on Dad's old manual from the cedar bureau, I'd guess from the '50's
So, googled;
http://www.cedarbureau.org/installation-and-maintenance/

They are saying not to interleave felt with sidewall shingles and shakes. Busted, I wonder why  will send an email and report back. I'm stuck saying what I hate to hear "always done it that way", not good. A quick look at the roofing section says to only interleave on roofs with shakes (a shake is split where a shingle is sawn, I prefer shingles personally) Their instruction are the same as I was taught in regards to where to place the 18" width of tarpaper... double the weather exposure up from the bottom. For instance, I was running a 5-1/2" exposure, that was my first pop, the second was 11" up from the bottom of the course and the felt is laid to that line, you don't see felt, it is a double layer of shingles back from the face in the exposed area, which is triple layer+ deep over a layer of sheathing felt. ..(18" tarpaper, old chain on you buddy's chainsaw, fast)

Look up FRT wood shingles and you'll probably get hits (FRT, fire retardant treated)

Way OT,
Several years ago a friend called, he was working on a historic register house in Richmond (rare enough after the fire in '65) It had white oak shakes and he had lined up one of our local guys up here to make them. The man is quite experienced. The inspector had stopped it and demanded that the shakes be graded. The question to me was "is the inspector making this up?" In that first conversation I agreed, it sure seemed over the top for a non structural item to require grading. I was wrong, they did have to source graded shakes  I can about guarantee the original shakes had no felt anywhere. I wonder what they did on the restoration now.

[JRR]

I wonder if the concern would be the drying ( or more precisely; "the not drying") of the bottom side of wooden shingles if they are against anything that might restrict air flow?

I think I will continue to be a non-fan of wooden shingles.  They look great however.

[akwoodchuck]

They are saying not to interleave felt with sidewall shingles and shakes. Busted, I wonder why  will send an email and report back. I'm stuck saying what I hate to hear "always done it that way", not good. A quick look at the roofing section says to only interleave on roofs with shakes (a shake is split where a shingle is sawn, I prefer shingles personally) Their instruction are the same as I was taught in regards to where to place the 18" width of tarpaper...

I've only ever seen that on roofs....wonder if it has something to do with disruption of air barrier? Freezing wind blowing through every power receptacle in winter is no bueno, quite common in older structures....that's why I stick with Tyvek....

[Don_P]

I doubt it, there is still an initial layer on the wall sheathing, on this job it is tyvek... which I recall the initial tyvek had trouble with cedar extractives... forgot to ask about that in the email query. Anyway, email sent, hopefully will have a response soon. Still haven't found Dad's old copy to compare. I have a feeling it is one of those cases of "It isn't what you don't know, it's what you know that just ain't so". Back to the op that we have left hanging... same thing... send a query to the t-111 manufacturer asking for a detail.

[Don_P]

Response came back, 9 attachments as well, I'll try to read through them tonite 

Hi Don,
There is too much to discuss via e-mail.
Briefly, the felt interlay is utilzed on shake roof application as shakes can be installed on a roof in two or three ply application; the felt interlayment acts as a 'Third-Ply' (see attached CSSB-Technical Bulletin Felt).
Also, the felt interlay acts as a baffle for wind driven snow when split faced shakes are installed on a roof (p.4 in the CSSB Roof Manual); felt interlay on shakes are meant for roof application - not sidewall.
Shingles do not require a felt interlayment on a roof as shingles must always be installed in a three-ply application. Also shingles have a sawn face and back.
Attached are documents FYI; if you have any additional questions, please do not hesitate to call me.

[JRR]

interesting.  The writer is making a clear distinction between shakes and shingles.  The felt is not "required" for shingles .... but does that also mean "not recommended"?  Is the felt seen as detrimental for shingles?

[Don_P]

There is a clear warning not to use it unless required to... but no explanation, I need to call.
The caution is in this doc;
http://www.cedarbureau.org/cms-assets/documents/148583-214326.felt-bulletin-update-01-14.pdf

This is another one I read in a builder mag several years ago, it is one he attached. It does a good job of explaining what felts and wraps do. Walt, there is a caution on felt or housewrap and t111 in that doc, lower half.
http://bct.eco.umass.edu/publications/by-title/housewraps-felt-paper-and-weather-penetration-barriers/

I just got in at dark so just reading myself, I'll try to find links to his attachments as I go and keep editing and adding those links below this line. Happy reading.

Installation, Care, and Maintenance of Wood Shake and Shingle Siding
http://www.fpl.fs.fed.us/documnts/fplgtr/fpl_gtr202.pdf
They want plywood sheathing if direct application.

Fasteners... SS staples only, tonight is just getting better and better 
http://www.cedarbureau.org/manuals/imperial/2015/WMI/WallManual-0407-i-p5.pdf

Bingo, the explanation, pg 5, felt between smooth layers traps moisture, hinders drying and causes "felt rot";
http://www.fpl.fs.fed.us/documnts/fplgtr/fpl_gtr201.pdf

I've got my method locally on a 7 year old building I'm in and out of often. The others coming to mind are shake... so the worst 2 applications are on friends buildings, could be worse. These are in gables only which helps... but I'm not doing it that way again... wonder how much a box of SS staples runs. Essentially the reasoning was the same in the end for felt under t111 and between shingles, too tight to dry. JRR, that simple question bloomed, reread your reply #17 

[Dave Sparks]

Not sure if this relates but for a metal roof and class A fire rating, you can't use tar paper.

Versa Shield manufactured by Elk as an underlayment as it has been tested and carries approval for fire ratings under metal roofing. - See more at: http://www.metalroofing.com/v2/forums/index.cfm?action=mboard.members.viewmessages&ForumTopicID=4840&ForumCat
egoryID=1#sthash.PypDAkjN.dpuf

[JRR]

In the distant past of my childhood, I remember wooden (not cedar!) shingles that required constant maintenance.  Of course there was never enough money to do repairs "completely", or "right".   Being a child, I had no part other than discovering leaks (to my delight!)

If I HAD to install wooden shingles today, not knowing anything about it ... and wanting to "cover my rear/all bases":  On the sheathing would be installed a two-ply covering of roll roofing (not mere felt, and the roll roofing would be without the shingle-cuts and with the stone pebbly surface.).... some "Oops" latex paint, with sand mixed in, would be applied for additional life and some fire resistance.  (I've done this on old near-flat built-up roofs)  Next 5/4" furring strips would be attached through to the rafters.  Then purlins would be installed for the shingles/shakes.  Instead of felt, galvanized welded wire mesh (1/2") would be interlaced with shingle courses on roof overhangs, eaves, apexes ... as many courses that the wallet could afford.  This mesh should add some wind and fire resistance and perhaps help drying.  i would also place a bead of poly sealant between shingle edges ... just to help the rain go downhill.

This all from a guy who has absolutely no installation experience of wooden shingles ...