How to place a new wall in a continuous mathematical alignment with existing wall

Frye

I am planning to add a North/South running wall next to a building.

I don't want to assume that the building is square, therefore I do not want to use the existing East/West running wall as my reference.

The new wall will also run North/South and I want it to be in perfect alignment with the existing wall. The new wall will be about 20 feet long.

I have considered using a chalkline to make the line for the new wall, but I am concerned about a lack of precision using that method. I have a similar concern about using a laser and trying to shoot it along the wall by eye.

What other methods might one employ?

I have considered some fancy triangulation, but the layout of the structure introduces some obstacles with that.

Thank you.

Termite

Lay it out with strings and see how you like the placement. Or just lay the 2x4 bottom plate down (loose) to check the dimensions before committing to it.

BigJimmy

Without trying to sound critical, I guess that I don't understand your issue.

Per your post, your major concern seems to be that the new wall will be parallel to the existing wall. As said before, that layout is pretty easy. On the other hand, if the wall that were using to lay out to is not square to some property line, then you have the choice of making your wall parallel to the exit wall (and therein not plumb to whatever your control is) or making it parallel to the property line and therein not parallel to the existing wall. The real question is: What are you trying to accomplish?

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AtlanticWBConst.

Use a Builders transit level.

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HooKooDooKu

I don't understand why you would even consider using an east/west as a reference point for building a north/south wall that is going to parallel and existing north/south wall.

So either I don't understand what you are trying to do or the answer is too simple...

Go to one corner of the building and measure the distance off for the new wall. Drive a stake into the ground at the desired distance. Go to the other side of the building and do the same thing. Now run a string between your two reference points and thats the spot for your wall.

Frye

Thank you for the ideas.

For clarification, my goal was to extend an existing wall. The final product is to be completely straight so that it looks like the wall was built to that length in the first place.

I really liked the builder's transit idea, but ended up using a laser because I own one and would need a week or so to borrow a transit.

I did my best to split the laser dot in half. Half of the laser beam at the near corner of the building and the other half at the far corner of the building so that the laser beam was as close to the building as possible. (Thereby confirming a line that is inline with the existing wall)

The laser revealed some places where the existing wall bows in and outward so I had to decide on the best reference points.

I made stake marks along the laser beam.

Actually, I marked on the wall plates because this is a support beam going into place on a 2nd story room addition.

Bondo

Ayuh,... A simple String Line would do that....

detailedEye

What Bondo said. String is very handy for layouts...

CrossWorks

That's exactly my thought...lol.

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Big Bob

Frye, please do not be offended, I mention this only for your own good.

It feels like you are over thinking this. A straight and true extension of a wall.. does not need to be a mathematical equation.. your lazer will only give you a point to point referance.

get some wood L blocks for masony.. 3 sets for.. low..middle... high..
and a ball of string. Set a guide post past the new corner...and plumb it.. block out the string... and make you plan..

With care you will be able to make your new wall just as imperfect as the old wall...

and keep it straight and good to the eye.