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T-111 siding advice please

xtal_01's picture

I am about to build a large workshop.

Money is tight so I am going to put T-111 on it for now. Cheaper than sheathing and siding ... I can side it later if I have the money.

Anyway, T-111 scares me. I have seen so much of it rot.

I am putting cement board from the ground up to the 24" level. This serves two purposes. First it covers the foam around the pad and second it keeps the T-111 away from the ground.

Now for my real question:

Normally, I would just use a piece of "Z" flashing where the cement board and the T-111 meet.

I just keep thinking that the edge of the T-111 will always wick up the behind it and stay wet ... thus rot.

I am thinking of taking the extra step of notching the wall, making a special piece of flashing that goes deep into the notch and letting the edge of the T-111 to hang free ( for say an inch or so ).

I am thinking with say a 1/2" on the bottom and and inch on the back hanging free it would dry better and have less chance of rotting.

The notch will not have any affect on the structure as the building has a double stud wall (trying to be as green as I can afford to be).

Any thoughts ??????

I just have not experience with T-111

Thanks ..... Mike

fundamentals first (post #215101, reply #1 of 12)

First thing i'd worry about is trying to provide plenty of roof overhang and height above grade. If you can do a good job of that then gettin' fancy is less pressing.


It sounds like you are trying (post #215101, reply #2 of 12)

It sounds like you are trying to create a drip edge.

You can do the same thing easier by rabbeting or chamfering the back lower edge of the siding.  The rabbet or chamfer should be 1/4 in.  This will work well if the siding is 1/2" or thicker. 

I would treat the cut with wood preservative, and seal with primer before installing.

Leave at least 1/2 in between bottom of siding and the horizontal leg of the Z channel, and make sure the channel is sloping away from the building.

Exactly what I am trying to do! (post #215101, reply #4 of 12)

Never thought about undercutting the sheet.  I was trying to do the same thing by cutting the stud.

I think your idea might be easier than mine and do the same thing.

Realy, I am just trying to keep the water away from the bottom edge.

With your idea, I could possibly even do this to the middle "z" flashing where the two sheets hit.


Thanks ..... Mike

Middle "z" Flashing? How (post #215101, reply #7 of 12)

Middle "z" Flashing?

How tall is this building?

A sketch of what you are trying to build will be helpfull.  We can mark that up with suggestions.


I will try to attach pictures (post #215101, reply #8 of 12)

I will try to attach a schetch but I have not had luck in the past doing so on this site.

The building is 50 x 60 x 16 ft tall ... tall enough to drive a motor home in.

I have divided it into three bays ... all 20 x 50.  One for a machine shop, one for storage (RV) and flexible bay (wood working, welding, vehicle repair, ....).  The divided walls are not supporting.  I will have three posts (12.5 ft spacing) and lvl's front to back of the building supporting the loft and rafters.

There is a loft above the middle section (just because the roof is high in the center and it is wasted space).

I am trying to detail the walls right now.  When I get them done (I use Autocad), I can put up the drawings.  I would appreciate all the advice I can get.

I will try to attach a scketch (I also draw everything out in 3D ... use Sweet Home 3D or Google Sketch).of the building.

The pad is in (reinforced concrete with a thickend edge).  There is foam under the pad, around the outside and outward for about 2 ft (16" below grade).  No foam under edge (about 12" on compacted earth with stone over it) and under 6 spots I thickened for posts.

I wish I had gone with a standard footing/wall design and just put the insulation inside (this is how I did the house) but I was talked into this idea by the excavator, framer and concrete contractdor back 4 years ago when we started the project.  now they are all retired or left the State and I am trying to figure out how to use what I have.

Thanks so much !!!!!!!!!!!


Jericho, VT

shop_concept_drawing.jpg58.42 KB

another thought.. (post #215101, reply #3 of 12)

It just occured to me that if you are using the t-11 as sheathing and siding it is also your bracing so it needs to be nailed to top and bottom plates to be effective.  


Will and inch or two matter? (post #215101, reply #5 of 12)

Do you think moving the mails from say 3/4' to say 2" up will make adifference?

I have never used T1-11 before.  I just assumed it will still be stiff enough if nailed an in or two up.

Will it warp or ????

Thanks .... Mike

An ounce of prevention... (post #215101, reply #6 of 12)

Whatever else you do, backprime (oil-based) the sheets closest to the ground. In fact, back and edge priming is a good idea for all sheets. If your overhang is shallow, consider the kind of material you will lay around the perimeter of the building. Use something that absorbs rain splatters. Keep your wood siding at least 8" off the ground. Someone correctly mentioned that since your T-111 serves a dual purpose (sheathing/siding), you need to nail it to the sole plate, with the sole plate bolted to the foundation wall (sheer issues). Absent that you will need to put a metal brace into the wall...easily done. To guard against warpage at butt joints, consider installing nailers in the wall. Remember the ancient addage: An ounce of prevention....

Mel Fros

I agree comletely!!!! (post #215101, reply #9 of 12)

Completely agree.  In fact, I was planning on oil based stain but after a lot of homework, decided on oil primer and latex fisish coats.

I even put in the drawings all sheets to be back primed 6" from cut edges.

the buildign is 16 ft so I need two sheets on the side.  I was going to nail it at the bottom, at the zee flashing and at the top ... along with at the studs (16" centers)

Will this be enough or do I need more nailers in the middle?

There will be cement ( or hardie or ???) board up to the 24" mark so the bottom edge should for the most part be out of the weather.  I also have 24" eaves on the building to help keep the weather away.

One of my biggest problems is how to cover the foam around the foundation.  I know cement board is not rated for ground contact but I can't afford PVC.  Aluminum or a rubber coating will fall apart when my weed eater or lawn mower hit it.  I am hoping the backer, covered with stamped cement or stucco will take the abuse and remain intact.


Thanks ..... Mike

Jericho, VT

bracing.. (post #215101, reply #10 of 12)

the top plate and bottom plate have to be nailed to the sheathng to be braced. if the sheathing [in this case T1-11 doesn't span unbroken from plate to plate you have to supply continuous blocks at any joint[s]. 


As for warping any joints must be nailed to blocks or other framing or it will probably warp. Here we get syp T1-11 which is warp prone any way. Fir is less so but still all joints must be backed.

Actually i kind of like T-111 for the right application. i was doing some work at a site a month back adjacent to a shop I built and sided with T-111 back in the 80's and the stuff didn't look too bad still. Seems like the walls are 12'.

If you are in a big market you might want to check to see if you can get sheets longer than 8'.


Big market .... hmmmmmm (post #215101, reply #11 of 12)

Thanks so much for the advice!

I definitely will block the sheet at both ends ... maybe even in the middle.

As for a big market .... I was born and raised just outside of Niagara Falls Canada.  I lived in SC for 13 years.  Vermont is very very rural!  Our largest city only has a population of 42,000 people.  We only have one (maybe two now) walmarts in the State.

It would be great if I could get longer sheets ... I might try NY ( only a short drive over the lake) or even Montrial (we are less than an hour from the boarder).

Thanks again!


I hate T111 but the way you (post #215101, reply #12 of 12)

I hate T111 but the way you plan to use it sounds fine. I would use an aluminum Z flashingbehind it and add one more step. I'd prime the bottom edge and back throughly before installation and use a 5 way tool tto gap the panels off the flashing just a little so it can't sit in water. When it's all hung prime the outside and I doubt you'll ever have a problem. Most T111 rots because it wasn't back primed and especially because the bottom edge is exposed.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.