How to use rotary laser level to measure desired final height for porch?

[Loungeact]

Hello,

I'm in the process of installing an above ground pool (height = 1.2m) that will sit in front of an existing porch.

It will not be tied into the original porch initially, and will be a standalone structure.

Forward planning, the idea will be to extend the current porch (desired final height) around the pool and sitting over the edges of the pool, finally tieing it all together.

I get the general process, just not 100% sure about how to set the reference point, and markup etc.

I'm new to the world of using a rotary laser level - I've got a staff and receiver.

What is the best way to ensure that the final height of the pool edge will sit least say 105mm (90mm joist / 15mm board) below the current porch level?  In other words, ensuring that I have cut out or built up the ground / pad for the pool to the right level, so that down the track I can extend the current porch so that it sits over the edge of the pool?

If pictures will help, I'll upload later.

[MitchellMc]

Hi @Loungeact,

You're on the right track using the existing porch as your reference point. The most important thing here is establishing a consistent level to measure down from, and the porch gives you a perfect starting height. Since the pool is 1200m m tall and you want its top edge to sit 105 mm below the porch level (to allow for a 90 mm joist and 15 mm decking board to eventually bridge over it), the ground pad for the pool needs to be set 1305m m below the height of the current porch. 

To do this, set your rotary laser level so that its beam lines up with the top of the porch. You can do this by either mounting it on the porch itself or using a string line to project that level out to the area where the pool will sit, then adjusting the laser to match. Once the laser is set, use your staff and receiver to measure down from that beam until you reach a reading of 1.305 m. That will be the height you need to build or cut the pad to, ensuring the pool sits at the correct level relative to the porch. Once that reference point is locked in, it becomes fairly straightforward to mark out the rest of the area and ensure everything is level. 

Please let me know if you have any questions.

Mitchell