How can I use a rotary laser level with a building in the way?

I am looking at possibly building a much larger garage over top of my existing garage. The current garage has eight foot ceilings and the new garage will have 16 foot ceilings. I think the new garage would go over the ridge of my current garage. I want to do this so I don't have to find storage for the stuff in my current garage.

Anyhow, how would I use a rotary laser level to level the new footings with a building in the way? I am told it can be done, but my Google searches have failed me so far.

Layoff the elevation of the existing footing to "line of sight" stakes. Use as many as required to circumvent obstructions.

Use a water level.

Any windows?

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Originally Posted by Tom M King

Any windows?

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+1 on water level more accurate then laser

You'll need to establish more than one reference point since you can only use line-of sight with a rotary laser. Set one and then set one or two more based on that initial reference.

Use one laser, make a mark on the corner of the building...move the laser around the corner and align it to the original mark. Now you can project the same level line around a corner.

It sounds to me like the easiest way would be to get a really long grade pole and put the level on the peak of the roof. You'd also need a stepladder that was tall enough for someone to climb up to the line and read it.

That might sound a little goofy but it's very similar to shooting a DIY topo, once it's set you're pretty much good to go. I've used a 16' 2x4....probably looked a bit stupid walking around in the middle of a pasture with a 2x sticking up in the air though. :)

......You might give it a go and try to put on like you couldn't find a shorter 2x

Using super long grade poles and so forth sounds kewel, but just transfering the reference as both Dick and I have suggested is easy, accurate and stays at ground level.

I thought a rotary laser level is the way construction is done these days. I bought a good one (At 50% off it was still around $400.) from Amazon Warehouse Deals about two years anticipating my garage project. I didn't do any research into alternatives like the water level.

A water level might still be an alternative and just sell the laser level. It looks like brand new. The included batteries are unopened. I have no idea why it was returned to Amazon.

If you use a really long grade pole make sure it’s vertical. If it is tilted either away or towards the laser it can throw you off by inches.

Brian,

Before retiring, the way we leveled MR scanners, CT scanners and x-ray equipment was using a water level. I helped a guy side his house and we used a water level. At the same time, I have a Bosch non-rotating laser level I use here at home. Water levels work easier if there is more than one person working, using it at the time.

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Originally Posted by Brian Elfert

I thought a rotary laser level is the way construction is done these days. I bought a good one (At 50% off it was still around $400.) from Amazon Warehouse Deals about two years anticipating my garage project. I didn't do any research into alternatives like the water level.

A water level might still be an alternative and just sell the laser level. It looks like brand new. The included batteries are unopened. I have no idea why it was returned to Amazon.

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Brian, I also bought a rotary laser for my shop project. For me, I feel it's going to be a lot more useful and less cumbersome than a water level. I know a lot of folks prefer a water level and I respect that; I prefer the tech.

About the grade pole. Lean it forward and backward, the shortest measurement is plumb. Way back in the dark ages when we used a transit or builder's level that is how we did it.