The first course sets the line every course above it inherits.
T1-11 goes on in full sheets, vertically, with the grooves running up and down. Snap a level line where the bottom edge of the first course will sit, set something along that line for the sheet to rest on so the wall carries the weight, lift and set the bottom edge onto it, plumb the vertical edge and confirm the line, then nail it off and move up a course. Check whether your sheets are shiplap-edge or square-edge before laying out the wall. Fastener spacing, edge distances and ground clearance come from APA and from the instructions for the specific panel you bought, and where the two differ the manufacturer's instructions govern.
What T1-11 is, and why the edge matters
T1-11 is panel siding, plywood or OSB, with vertical grooves milled into the face. It is commonly sold in 4x8 sheets, and taller sheets are available.
Two edge treatments are common, and they change how you handle the vertical joint:
- Shiplap-edge. The sheets lap each other at the joint.
- Square-edge. The sheets butt, and the joint is covered with a batten.
Check which one you have before you snap a line, because the layout across the wall depends on it.
What governs the numbers, and why we do not publish them
We do not publish fastener schedules, edge distances or clearance figures for a panel we did not manufacture. Those come from APA and from the instructions for your specific product, and where the two differ, the manufacturer's instructions govern. Have that document on the job, not in a truck.
Every crew improvises the same part: holding a full sheet flat and level while it gets fastened. That is the part we help with.
The sequence
1. Snap your line
Set a level line where the bottom edge of the first course will sit. Everything above it inherits this line, so a sheet that goes on a quarter inch out puts every course above it out too.
2. Give the sheet something to rest on
This is the step that decides whether the job is comfortable or a fight. The wall should carry the weight of the sheet, not a person. Crews do this with nails tacked along the snapped line, with scrap cleats, with a screwed ledger board, or with purpose-built supports.
3. Lift and set the bottom edge down onto it
Two people, one at each end. The sheet is now sitting at the right height and is not moving.
4. Check it before you commit
Plumb the vertical edge and confirm the bottom edge is still on your line. This is the last cheap moment to fix anything.
5. Nail it off
Both hands free, working from the line, to the schedule in your panel's instructions.
6. Remove the supports and move up
Where EZpanl fits
Our 16-piece siding hook kit is 16 powder-coated 11-gauge steel hooks and one EZhandle. The hooks nail to the wall along your line, and the bottom edge of the sheet rests on them while your crew fastens it. Once the sheet is set, the blades sit behind it and only the feet show below the bottom edge. Tap up on a hook to release it and move up a course.
It replaces the improvised ledger and gives you the same line on every course instead of a fresh guess each time. Consult the current EZpanl instructions for the panel products and conditions it is approved for.
It is not a way to work alone. Our published safety guidance requires a minimum of two people at all times and states that the tool is not a replacement for a second worker. If you are working alone, we wrote about that here.
What crews get wrong
- Snapping the line off the foundation instead of off level. Foundations are not reliably level. Set your line with a level or a laser, then check the foundation against it.
- Fastening the first sheet before checking plumb. Every course above it inherits the error.
- Letting the sheet take its own weight on the fasteners while you work. That is what causes the slip you find three courses later.
- Leaving the manufacturer's instructions in the truck. The clearance and fastener numbers are the ones an inspector will ask about.
Questions crews ask
Can you install T1-11 by yourself?
People do, and some tools are sold for it. Our own instructions require a minimum of two people at all times. We go into the detail here.
Does T1-11 go on vertically or horizontally?
Vertically, with the grooves running up and down. That is what the product is milled for.
What holds T1-11 up while you nail it?
Whatever you set along your level line: tacked nails, scrap cleats, a screwed ledger board, or purpose-built siding hooks. The point of all of them is to get the wall carrying the sheet.
Do you need a ledger board for T1-11?
No, though plenty of crews use one. It works and it is free if you have offcuts. The trade-offs are that it has to be leveled, fastened and removed on every course, and it leaves fastener holes in the finished face that need attention.
What is the difference between shiplap and square-edge T1-11?
Shiplap sheets lap each other at the vertical joint. Square-edge sheets butt together and the joint is covered with a batten. Check which you have before you lay out the wall.
How far off the ground should T1-11 sit?
Follow the clearance in your panel manufacturer's instructions. It varies by product and by what is below the siding, so we do not publish a number here.