# How to locate a line parallel to adjacent building for a new building

I want to build a new building next to an existing building. The new building must be parallel to the old building, but shifted forward, as shown below. What is the best way to find a parallel line to the existing building in order to mark and set the footers for the new building?

For example, an existing building is here:

``````+----------------------------+
|                            |
|                            |
|                            |
|                            |
+----------------------------+
``````

I want to add another building a few feet away, shifted halfway to the right but maintaining parallel walls with existing building:

``````               +------------------------------+
|                              |
|                              |
|                              |
+------------------------------+
``````

What's the best way to find the parallel line?

• How far apart? Is the ground between them flat? Level? Jun 5, 2019 at 18:10
• Let's say 50 feet apart, yes the ground is flat with no obstructions between them. Jun 5, 2019 at 18:13

``````+----------------------------+
|                            |
|                            |
|                            |
|                            |
+----------------------------+

[*]-------------------------[-]---------------------[*] <-- stake with nail
^-- stake with nail at      ^-- stake at roughly           set under extended
arbitrary distance          the same distance,         carpenter's line
from bldg                   with mark at exact
distance

+------------------------------+
|                              |
|                              |
|                              |
+------------------------------+
``````

Set a reference line as shown, then just take measurements from that as needed.

• I see how this could work, but what if we failed to measure from the existing building at an exact 90-degree angle? This would skew the stake placement, causing the new line to be out of parallel. Am I missing something? Jun 5, 2019 at 18:53
• Within a few inches of square the error is negligible. Carpenters would get nothing done if they had to square every measurement they made. :) Make it a point to eyeball for square and be happy. If you're really worried, lay a framing square or something against the building as a guide. Jun 5, 2019 at 19:08
• You can test this after your line is set. Swing side-to-side and find the point with the shortest dimension. That's square, or close to it. You'll find that there's a range where the measurement doesn't appreciably change. Check both corners of the building for consistency. Jun 5, 2019 at 19:22