I’m putting new T1-11 over old unpainted T1-11. I’m planning on priming the new on both sides before I put it up. I would like to know if I need to put up 15# tar paper over the old and then put up the new?
Also in another area, of new construction Im putting up primed T1-11 over studs. Do I put up tar paper between? I assume I do but have gotten mixed info.I will be using fiberglass insulation with the vapor barrier facing in. I’m up in N. California very wet and rainy during the winters.
Thanks very much for the truth I know you will impart.
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do not use TP .
is this siding? how ya gonna detail the flashings and trim?
Spheramid Enterprises Architectural Woodworks
What are dreadlocks made from?
Thanks for the reply Yes the T1-11 is siding in both cases. Are you saying not to use tarpaper in both cases?
Yep..it'll hold condnsation or at least impede the transfer between the laminate you create..with the grooves in Tiajuana Eleben I see bugs...either way.
Cant ya strip the old? Spheramid Enterprises Architectural Woodworks
What are dreadlocks made from?
Yes I can take off the old but thought take it would be some added insulation and not really effect anything
Edited 7/9/2005 10:48 pm ET by mendo
nope..t1 is as insulative as ..well..wood. Ya dont gain a thing, except headaches.
what about the trim details..? Spheramid Enterprises Architectural Woodworks
What are dreadlocks made from?
Haven't got as far as the trim details yet but saw that there was alot of info in the archives on it.
I say in the area of doubled T1-11 no TP. In the new construction area of single layer of T1-11 on studs, use TP as it will act as a secondary weather barrier.
That way, in the case of the single ply T1-11 any moisture that may penetrate the lap seams of the siding or at the trim will be kept to the outside of the structure rather than getting into the stud cavity and the insulation.
In the case of the double layer of t1-11 the TP would possibly trap moisture between the 2 plys causing rot. Like Sphere said, the best thing to do though would be to strip off the old T1-11.
Matt
Edited 7/10/2005 7:57 am ET by Matt
Maybe I am suppose to start another thread, but while you are on the subject of T-11 siding. My house has the cedar veneer T-11 with the fake spacing of 12 inches on center board and batten. I would like to make it true board and batten with cedar 1X3 strips. I have looked at true board and batten trim details and wonder if I can apply the same to the t-11. I do have concerns with the horizontal bottom strip. The ones I have looked at have a 1X4 with a champher for water run off. I guess you would also have to caulk the entire length? Any advise would be of great help Thanks
Can't see the building this is going on.......but how about Tyvek or Typar over the old, then vertical furring strips, then your new T1-11? Screen top and bottom of this assembly to allow for air movement thru the space and to keep the bugs out. IOW, rain-wall.
In fact, you should also be able to use TP if you furr out the new T1-11.
You'll have to resolve the doors and windows, of course.....and maybe other stuff we can't see from here.
Maybe you've already considered the above and would rather avoid the thicker build-up............and it seems like a lot of hassle (windows and doors) if simply replacing the old is doable. Of course, there is a benefit to a rain-wall in a rainy environment.
Knowledge is power, but only if applied in a timely fashion.
Edited 7/10/2005 11:09 am ET by GOLDHILLER
thanks for all the info but what is " IOW "? Also in usual construction tarpaper or tyvek is put over ply sheathing under siding so why not between layers of T1-11 ?
IOW=in other words
short speak for us lazy typers.. Spheramid Enterprises Architectural Woodworks
What are dreadlocks made from?
IOW = in other words
I can't ............because I've never tried it ..........nor seen the results of "direct-layering" two sheets of ply with housewrap or TP in between...........and therefore won't make a bold definitive statement concerning the practice (particularly in a "wet" envirnoment).
But consider that usually when you see ply sheathing and housewrap, the siding is usually either lap siding, vinyl, Hardi siding, etc. These all leave some manner of gapsiosis between themselves and the ply/housewrap. A little breathing room, if you will. If you tried "direct-layering" and water seeped between the two, it would be in direct contact with the backside of your T1-11 with no breathing space of any manner to dry out again. Much the same phenomenon that you see with solid stock built-up deck girders and such. Without a cover-flashing for the lams, water can seep/wick in there between them, but can't dry out and degradation follows.
And the above just reveals what may happen concerning water entering from the exterior side primarily at the vertical lapped seams and such.....and says nothing about the water vapor that may migrate into the stud wall from the interior side..........also with no "ready-route" of dissipation/means to easily dry out again. That's gonna have the potential to soak more of the backside of the T1-11. It would/could theoretically move thru your Tyvek/Typar and then condense/be trapped right onto the backside of the new T1-11 where it gets soaked up. The glues between the laminations of the T1-11 would impede drying to the exterior side (fat chance of much drying anyway with a cold rainy season at hand all winter).
And so......I guess I gotta agree with these other guys that direct-layering is a dubious procedure .......at best. In a wet environment, even more dubious. Although I gotta say that on the surface that Tyvek on studs and then one layer of T1-11 looks much the same as what it is you're proposing..........somehow two layers of T1-11 gives me the heebie-geebies.
Knowledge is power, but only if applied in a timely fashion.
Edited 7/10/2005 12:10 pm ET by GOLDHILLER
Edited 7/10/2005 12:12 pm ET by GOLDHILLER
Edited 7/10/2005 12:20 pm ET by GOLDHILLER
Edited 7/10/2005 12:25 pm ET by GOLDHILLER
Dammm..that was neat..lets try it again..(G)
same phrase and same time..
eeeriee. Spheramid Enterprises Architectural Woodworks
What are dreadlocks made from?
I'll 2nd GOLDHILLER and others, in large part because, here on the "Wet Coast" the use of T-111, while widespread (mostly from the 70's and 80's construction) doesn't always have the lifespan of other siding options....in large part, because a good, 5/8" premium T-111 is relatively expensive, so a lot of tract homes and modulars are sided with inferior grades and less thickness.
Usually, T-111 fails starting at the bottom where the plywood edges were never sealed and the raw ply sucks up water like a sponge.
Several years ago I replaced the windows in a nice home, built in the 50's for a local, albeit small, timber baron, that was sided with full 3/4" T-111 that was manufactured entirely out of Western Red Cedar veneer, all 7 plies of it. I've never seen it anywhere since, but it was in perfect condition except for one corner where a dog had gnawed a small area.
Double-wall construction (sheathing and VP prior to siding) is the general rule on most decently built homes out here, partly because of shear requirements. And because most HO like plantings right up next to the house creating a potentially damp area above the foundation, I got into the practice several years ago of running the first course of sheathing (horizontally) with PT plywood.
I would be reluctant to install T-111 over old T-111; I would always have a concern that I buried a problem somewhere. In addition, as mentioned, the trimout for doors and windows might be a PITA.
What I often ran into in remodels in the past is the original T-111 cut precisely to fit around the window frames; usually the old mill-finish aluminum type that sweat and create rotted framing in the RO and the back of the T-111.
Premium 5/8" T-111 is relatively expensive (using a lesser grade, IMO, is like installing cheap roofing, giving a limited lifespan....to do your project with good, long-lasting results might be only slightly more expensive to strip to the studs, sheath with OSB or CDX Ply, VB, trim and something like preprimed Certainteed or Hardi Fiber Cement.
Well I guess I won't be using tarpaper between the two layers of T1-11, thanks. For the record this is a small house I am talking of and the original T1-11 is not delaminating altho seemingly never had a finish and if it did it is long gone, the skin seems to be redwood or cedar, rough sawn 4" groove and I'm guessing, maybe 20 years old and 5/8" thick. The new T1-11 I'm using is 5/8" and is about $23 a sheet from Home Depot, I think it is pine skin, 8" grooves and looks clean, no plugs. 5 years ago I built a large shed/garage with a small enclosed room with the same T1-11 I'm going to use now, primed back with opaque stain and two coats on the face and ran the grooves horizontally. So far no problems , I like the horizontal effect even knowing it was not the recommended way
"rough-sawn 4" groove..."
T-111 is manufactured out of plywood. The face material, back and core materials may be of various species.
The process involves running the sheets through a specially designed sander, with a course grit, across the grain of the face, giving the "rough-sawn" appearance.
The sanding process is followed by running the sheets through a dadoing machine that mills the grooves to the desired spacing.
To install T-111 horizontally means you are exposing laminations of veneer at the bottom of each groove.
I'm telling you this so that when and if you install it horizontally, be especially attentive to thoroughly sealing and painting the bottom shelf of the groove.
Best of luck!
I used T-111 last house - I'd recommend you look into the 4x8 grooved Hardie product - it is ~$23 at HD here, will never rot and comes preprimed. I was not happy with the wood product, even though I paid for the higher grade. I think you'll be happier in the long run.
Out of curiosity.......can we assume the old unpainted stuff has delaminated?
Any other obvious sources/causes of degradation?
Sidenote: Don't forget to seal all the bottom edges of that stuff.....prime and paint..........or even use something better. And keep them well-sealed throughout the years. Very vulnerable to sucking up water and rotting down there.
Knowledge is power, but only if applied in a timely fashion.