If I were making the investment, I'd definitely go with a laser transit level. Not inexpensive, but apparently easy to use as a one man/woman operation. I've yet to take the plunge, but I'm getting a lot more heavily sloped projects and it's starting to make some very practical sense. Fortunately, my newphew owns a construction company and has one that I can test out for myself before getting my own. Love the family members in a related field - he recently got a small dump truck he offered for my occasional use as well :-))

Ours is a Spectra Precision laser level. I love it, and I'm actually looking at buying one for myself for my freelance work outside of my full-time job. It's simple to set up and like some have said above, it can be used by one person. I actually shoot grades for every design I do, even if it's as simple as a front walk. With the laser level, I can get the data I need from a small yard in about fifteen minutes.

My answers are inline:

Will you need to determine horizontal position or elevation or both? OK, now I look like a dummy right off the bat. I am not clear on what horizontal positioning is....Elevations defintely though

Will you be gathering data for design purposes or control of construction or both. Both

What is the largest site you will commonly work on? City lot, 1 acre, 5 acres, 40 acres? To date the largest is 1-1/2 acres and these are the size properties that I need it for. They tend to be hilly or sloped, or have drainage issues. Most of my work has been on the typical Long Island 60'X 100', but those are almost always flat.

Will the work areas be relatively flat and open or sloped and or include large shurbs, buildings, or other obstacles to sight? Most until now have been relatively flat, but those that have not have had obstacles to sight.

Will you need the precision to design or construct hardscape such as concrete slabs, walls, drainage facilities? yes, yes and yes

Will you have to do the work alone or will you have an assistant. Mostly alone

Will you spend only a small part of your time using the equipment or will you be doing this type work for hours on many days. Small amount of my time

Do you have a budget? I was hoping someplace under $500. But if having to wait to afford the right piece of equipment makes sense, then I will.

Thanks! I appreciate all the feedback. Are there different option on the lasers that I should be aware to look for?

m

I really only know about what I've used, and ours seem pretty bulletproof. The two things I would say are to get two survey rods- the standard 16-footer and a 25-footer for bigger elevation changes, since you lose accuracy every time you have to move the transit; and look for value but beware of cheap. My brother bought one for $400-500 from a pond wholesaler catalog, and he's having to send it in for recalibration way too frequently.

Horizontal Position, location relative to other features of the site.

It's easy to see that in the construction phase it's important to be able to find the correct location, per the plan, for things such as the corner of a patio, starting and ending points for a wall, or where to plant a tree. With plan in hand, walk out and say "looks like it goes 'about here'. 'About here' will get you in trouble.

The same is also true when collecting data to map a site. Show a tree location a foot off from it's true location will probably be OK. PLace it on the map 5 feet from it's true location and the design may run into trouble at construction.

In the graphic below I show a site with 10 to 12% slopes. At the blue 'x' an elevation observation is taken. The spot is found to have an elevation of 94.0 Suppose the spot is shown on the base map 5 feet out of position at the red 'x'.
Looking at the contours it can be seen that the true elavation at the red 'x' is about 93. If the observed elevation of 94 is shown for this location it is the same as making a 1 foot error in elevation observation.

{{gwi:46329}}

What longislander needs is a system that can be run by one person, can collect both position and elevation data on sloped property, with relatively good percision, for $500.

To my knowledge, no such animal exists.

marcinde suggests a rotating laser and this could be the best solution. Let's take a look at how they work. Hopefully someone will step in if I get something wrong.

Rotating laser levels consist of a base unit mounted to a tripod and a receiving unit attached to a grade rod target.

The base unit sends a narrow beam of light on level, the beam rotating around the unit. Accuracy is dependant on how level the beam is. All newer units will have a compensator that will correct for less than perfert setup and keep the beam level. Also should the unit become out of level it will shut down.

The stronger the beam, the futher out the receiver will work, but there is a trade off with power and battery life. The speed of rotation also effects how the unit works. On some units the speed can be varied. A faster speed reduces the time the beam is on the receiver as does also the distance to the receiver. Suppose a unit is set at 200 rpm with the receiver at 25 ft. resulting in a receiving time of 50ms per beam pass. Double the rotational speed and the time drops to 25ms. Keep the speed at 200 rpm and double the distance to 50 ft and the time drops to 25ms. Do both and the time drops to 12.5ms.

At some point, the combination of beam power, rotational speed, and longer receiver distance, the unit will cease to function. Fixed speed units may have slower speeds to give greater coverage or one can change to a slower speed to expand the coverage.

At some point slower speeds cause an inconvenience. The receiver has a limited vertical range in which it will be triggered. Outside this range the unit tells you nothing. To find the beam the rod is slowly raised until the beam hits the receiver. On some receivers the vertical range of reception in about 2 inches. If while raising the rod the beam passes above the receiver on one turn and because of a slow speed the reciever is below the beam on the next pass, the operater has no idea where the beam is.

For this reason, receivers that have a trigger range that is longer vertically are much easier to use. Below is pictured two receivers for the Spectra Precision laser LL500. Note that the one on the left appears to have a much shorter range window(4) than the one on the right(5). You get what you pay for.

{{gwi:46331}}

Most of the precision for this type system is determinded by the receiver. Older units could only give 0.1 foot resolution and though great for basic grading they are useless for precision work.

More on the system use later.

Please hurry up pls. Yours were on the button questions BTW and I wonder if, considering the amount of use it would be better to rent the best rather than buy something second rate?

I wonder if Long Island is as regulated as Cape Cod as far as requiring surveyed plans for additions, new construction and septic systems. If so, there should be topo plans for many of the projects since many are a result of the mentioned site alterations. Contacting the surveyor or engineer may get you a very good base plan that you can fine tune with less sophisticated equipment than some listed above. I often work this way.

You can use some simple techniques to maintain very good accuracy. A 100' tape and a 30' steel tape will and carefully lining yourself up with wall faces works very well. There is also a device called a 90 degree prizm that can make this more accurate. You simply line yourself and the 100' tape up with the end of the house, being carefull to see that the two corners line up. The 90 degree prizm is a hand held device that you look along a known line (face of wall in this case) and the prizm looks exactly 90 degees to that line. As you move in or out along that 100' tape, you look for the items that you want to locate in the prizm. You note how far out from the corner of the house you are and them how far over the item is. Then you write down the coordinates and sketch them on accurately later. This can be done without the prizm, but itis more accurate with it.

A simple method for getting elevations without a dumpy level or "laser"* is to line your eye up with clapboards or shingles on the house. You know your eye is lined up with the bottom line of a clapboard or shingle course if when the course above looks like it is going down hill and the one below looks like itis going up. measure from the ground up to that clapboard course and note which course (ie, 3rd from the bottom) on the house that it is (you are doing this where you want an elevation, not next to the house). Since siding (hopefully) is always level you have a consistant reference elevation. I measure down to the threshold of the door from that noted siding line and crunch the numbers later on so that all elevations are related to the floor of the house. Often, the floor elevation of the house is on a refeence plan, so you can use real elevations.

Those are two simple, yet hard to explain, methods to have reasonable horizontal and vertical control to design a landscape. Sometimes this is adequate.

A surveyed base plan with added features from the methods above is pretty good for most residential suburban lot landscaping.

Certainly a "laser"* or a transit, or a robotic total station is going to be more accurate if you need it. If you are laying out elevations for construction you should have a dumpy level at minimum. As far as drainage goes, the flatter the site, the more accurate your methods should be.

(*Austin Powers)

Use of a rotating laser level.

All elevations are relative to some known point. In the case of construction, the plan will have a Bench Mark shown with the elevation noted. All construction grades are made compatable with, and derived from the Bench Mark.

When starting a map of a new project area where no known Bench Mark exists, it is common to select or set some point to serve as the Bench Mark and an arbitrary value is chosen for the elevation such that no part of the project will have a negitive elevation. It is important that a selected BM be one that will not be disturbed through construction. Some common BMs are the finnished floor of an existing building, a marked spot on a concrete surface, or a spike in the base of a tree.

A place is chosen for the laser base unit. It must have line of site to the BM and the unit head must be setup higher than the BM, but for all percision work the head should not be more than 6.5 feet higher than the BM. Consideration should be given for how much of the project can be worked from the position.

The tripod legs are firmly set such that the top table of the tripod is relatively level. The base unit is then mounted on the tripod and leveled.

The level rod/receiver is a three part affair, the rod, a rod bracket clamp, and the receiver. The bracket clamp fits on the rod in a way that it can be loosened and slid up and down the rod then locked down at any position. It has an indicater that can be used to read the value on the face of the rod and also serves as the mount for the receiver.

Note: the receiver can sometimes be moved up and down on the rod clamp bracket as a means to calibrate the system. Once this is set, it is a good idea to put a spot of nail polish that will span across the bracket to the receiver as a seal. A shift of the receiver on the bracket after work starts will lead to errors. Check to see that the seal is unbroken before and after all precision work.

The base unit is turned on and the rod is placed on the BM. The receiver is set to give close precision and the bracket/receiver is slid along the rod until the receiver is centered on the laser beam. Anyone with sense uses a rod graduated in units, tenths, and hundreths of a foot. The rod value is read from the face and added to the elevation of the BM. The result is the elevation of the laser beam and is called the 'height of instrument' or HI.

Once the HI is known then the elevation of any point in the coverage area can be found. The rod is set on any desired spot and the bracket is slid up and down until the beam triggers the receiver. In short you have to find the height that the beam is crossing the rod before the receiver will start to tell you it is too high or too low. On flat ground it is easier to make an initial good guess as to where this will be. If the beam height is such that you can reach the bracket to make the setting, it's all very easy. Things start to get unhandy when the bracket needs to be set 12 ft up the rod. You have to keep leaning the rod down to adjust the bracket until you get it in the right place. Once the receiver is centered on the beam the rod value is read and subtracted from the HI to get the elevation of the spot.

Work a construction project where more than a few points have the bracket out of reach and you will be ready to junk the system. Thankfully most construction projects are flat and then this system can't be beat. Tall folks have an advantage.

Mapping a slope can lead to many setups or a lot of out-of-reach shots, take your pick. Also tall rods are made in segments and to move the bracket to a different segment is more of a bother than sliding it to new place on the rod. There is a trick to minimize these problems when mapping slopes.

This seems to be turning into a book, and I'm skipping some stuff. Tricks to slopes later.

In the above post I used the term 'shot'. A shot is the reading or collection of data for a single point.

When mapping a slope with a rotating laser it's best to start on the high ground and work down the slope. marcinde suggested a 25 ft rod. On sites up to 0.5 acre the use of a tall rod often means the entire site can be shot from a single base unit location. The 1.5 acre sites that longislander wants to work will require multiple base unit setups.

Receivers will have indicators on the face that tell whether it is above, below, or on beam. It may have colored lights as a secondary indicator and many if not all will have an audible sound as well. When the receiver is high up on a tall rod you can't read the face and you will work from the secondary indicators.

In an earlier post I talked about the importance of position or location for any given elevation observation. At some point both the position and elevation must be determined, but it doesn't matter which comes first. When mapping a slope, no particular points are required, so you are free to set a position and then find the elevation for that point, or you can do the elevation first and then find the position. When the receiver is above your reach on the rod, the later method is much easier.

In the graphic below I show a 1.5 acre sloped site. The base unit has been setup to be a little higher than the high point of the property. The HI is 102.46 A number of shots have been taken and are marked with a red dot on the graphic.

{{gwi:46334}}

As can be seen I have worked down the slope to where the receiver must be high up on the rod to continue. To get shots along the contour of elevation 98.0, I subtract 98 from the HI of 102.46 to get 14.46 The receiver is set on the rod to read 14.46. I walk to a place on the slope a little more than 4 ft below the last shots taken at elevation 102. My footsteps are shown as a dashed line.

From this trial spot I slowly raise the rod until the receiver beeps and note how high the rod is above the ground. I then step up the slope to take up this vertical amount and repeat a new trial. This continues until the receiver indicates on beam when the rod is on the ground.

In short what I am doing is moving the rod up the slope rather than adjusting the receiver position on the rod, which is out of my reach.

Once the elevation is found, a felt tip marker is used to write the elevation on a wire flag and the flag is stuck at the shot.

I then move along the contour and a bit downhill and repeat the process. Once all the shots for this contour have been made the receiver is moved up the rod for the next contour to be run and the work continues. Most of the walking is across the slope rather than up and down, important to an old man.

Note: If the work is done in this way, when you get back to the office, drawing the contours of the ones shot is merely a matter of connecting the dots.

Once you are below the base unit coverage the unit must be moved downhill. I'll cover that next.

I wonder if anyone is still following this tread.

I am following, and intend to save it for future reference.

Please continue,

Thanks, Susan

I guess my wish list was much too big :-).

When the property is too steep or irregular, I do ask for a topo survey.
Problem is sometimes clients get them before they start construction on the house and then by the time I get there the topo isnt worth the paper it is printed on. Many of my larger designs are on the tail end of a major renovation of the entire house and the contractor has it in his contract to "clean up and grade the property" So all bets are off on the accuracy of the document.

Do you think that if I were to give up the part of my wish list and have assistance with this task, I would have a better selection to work with? Or the other option is to buy a 'make-do' transit and rent one when the job warrants it until I cant get one of my own of the higher caliber?

Thanks,
Marg

If the jobs are worthy, having the client get out the same survey crew to do an as-built topo survey will probably run about $100 per hour for the crew and an hour or two of drafting at about $75 an hour to give you an accurate base plan.

The problem with getting a transit is it is completely useless if you are not trained on how to operate it.

Tape measures and a site level or laser level is going to get you pretty close which is close enough most of the time. If you need accuracy, hire the survey crew.

Marg, after you answered my initial questions I said that nothing would match your wish list. In a way I had answered your question. But it was a worthless answer, no good to you or anyone else.

In my mind I restated your question to "What equipment do I need to make the jump from basicly selection of plants for small residentual lots, to larger projects or ones that include grading, drainage, and hardscape features. It could be that there are a good many here interested in looking at that issue.

Laser levels are just one of many instruments that might be considered. If the interest holds, we might go on to discuss levels, auto levels, transits/theodolites, total stations, and even GPS.

laag is correct that a lot of equipment for small residentual lots is overkill. And there must be areas where the client market will allow a designer to call in a surveyor, engineer, lawyer, stonemason, or any other pro needed and the tab is passed through to the client. Somewhere, but not here. I don't have a clue as to how you get one of those upscale projects if all you have in your portfolio is some nice plant selection. Do you not have to go through some middle ground?

One of the first things that I ask is who the engineer was that did the septic, or who the surveyor was that did the certified plot plan. Then I make a call and they give (yes, as in free) me the cad file of the survey for the purpose of doing the landscape plan. It is very rare that there has not been a recent site or building upgrade that required one or the other. Not everything is located, but there are usually enough reference objects, most notably the house, to serve as a base to measure from. I have never been refused a cad file when one exists. This existing info can also be printed out at any scale by the engineer or surveyoy if you work on paper.

Some of these are small landscape jobs, but often they have swimming pools and walls, walkways, and stairs that require a certain amount of accuracy to design them. In either case, it makes sense to get the cad file as a base plan than to try to reinvent the wheel or repeat work that has already been done by others. It makes more sense when you add the cost of equipment, training, and software.

My guess is that the OP justs wants to get some elevation information in isolated parts of a property where s/he needs some more accuracy in order to know how many steps, or how high a retaining wall or perhaps whether there will be a puddle or not. A laser level makes sense for that. I used to use a construction level (level scope on a tripod) and a pitchfork with a measuring rod duct taped to it when I was flying solo. Crude, but effective.

Moving the laser base unit.

While taking the shots in the above example I would have had the receiver set to 0.1 ft accuracy. But any error in the readings made to move the unit will be induced into all following shots taken, so the the receiver should now be set for close precision, 0.01 ft or 1/4 inch.

The essentials of the operation are to select or set a stable object in a suitable location and make a precise shot to it to determine it's elevation. the unit is then moved and and the same object is shot from the new location to get the new HI. The object shot from both locations is called a 'Turn Point' (TP).

Note that you have great freedom of selection for the first shot. But the second shot must be to the particular point without disturbing the known elevation. The only way to do this is to set the rod on the TP and adjust the receiver on the rod to get the reading.

In the graphic below I show the base unit in two locations and the common TP.

{{gwi:46336}}

It could be that the unit is at the lower position and you want to move uphill. Or it could be the other way around.
Let's look at moving uphill first.

The TP is selected at a suitable elevation somewhat uphill but still below the beam. In the example I am using a short 2" by 2" wood hub driven in the ground. The first shot is made and the beam is low on the rod where it is easy to slide the receiver to make a precise reading.

Making the second shot is the hard part. The receiver is way above your head and every move of the receiver will require you to lean the rod down, walk out to the end, and then restand the rod. The first couple of times will get you in the ball park, but odds are, you will need a number of minor adjustments to get the precision shot. Trust me, it will be frustrating and time consuming.

Now let's look at a way to move from uphill to a lower position. The receiver is set a little down from the top of the rod. A spot on the slope that fits this receiver height is found in the same way that the basic shots were taken when running the contours except that at the end, the rod is not on the ground but rests on the shoe toe a bit above ground level.

The rod is kept raised but set a little off to the side. A hub is then driven at the shot point such that the top is about a half inch above what toe height was. Set the rod on the hub. You should get a little above beam signal. Keeping the rod up, again set it to the side and drive the hub down 0.01 ft and recheck. Continue until you get 'on beam'. Should you make a mistake and drive the hub down too far, lean the rod down and adjust the receiver up a very small amount and then return to checking. Always use a rod bubble to ensure that the rod is plumb while doing this operation! Once you've done it a few times, it becomes a fast easy way to get the high rod shot.

Now the unit is moved to the downhill location and the second shot is made to get the new HI. This shot is down low on the rod and is easy to do.

So if moving the hub is easer than adjusting the receiver why don't you do this when moving uphill? Because once the first shot is done the TP must not be moved! Moving downhill the high rod shot is the first one, but moving uphill the high rod shot is the second one. Now you know why I said earlier that when using a laser level start the project on the high side and work down.

@pls8xx- great tutorial so far. What has me confused is you're talking about shots at bigger rod extensions being difficult and cumbersome. Our receiver clamps onto the end of the rod, so if I'm on a hilly lot and need to raise the rod to 20', I just feed out enough rod to get there. Is there a reason you don't just do it this way? I haven't seen where it impacts accuracy, since we reshoot grades to lay out the jobs for install.

@laag, I'm wondering if the state of Massachusetts with all its wonderful laws (I'm a former resident) requires greater accuracy from surveyors. Here in VA, I always start a job by measuring the house, locating windows and doors, etc. I typically find that since my plans are to 1/16" accuracy and the surveyors are accurate to 1/10th of a foot, I have to adjust a couple inches when inputing data. Also, it's rare to find survey plats with elevations on them; typically, it's only high-end custom builds that provide them and on those, the builder has always made changes on site that completely invalidate those numbers. We designed a walled garden off an indoor pool area based on the submitted site plans; now that the house is in, the builder has moved soil so much differently from plan that where we had planned a 60" retaining wall, the ground is level walking out towards the woods!

@longislander, I'm sure this is looking like a lot of information building up, but it's a pretty simple setup once you've done it a couple of times. While GPS and more intense systems have been mentioned, for landscape work to include walls, decks, flatwork and grading, I can't see needing more than a laser transit, a couple of tape measures, some flags, some paint, and some stakes and string. I personally like knowing for 100% certain that if I have 54 risers on plan for a condo association, that's how many it'll take to get to the bottom.

A surveyor is not going to shoot a house any closer than a tenth of a foot because of having to jam a prism into or onto a corner. I'm trying to recall any reason that I ever had to be within a 16th of an inch on a landscape plan and I'm not coming up with one.

Topo surveys are pretty good up here because of the septic system laws. While it is true that a contractor can thrash a site, it usually is close enough to regrade to the design plan. The things that really matter, he can't do too much to. The floor of the house, the floor of the garage, the elevation of the septic system, the street, the grade at the property lines are what they are. What happens between those is equally maleable for the landscape contractor as it was for the builder. If it works on the design plan, it will be buildable in the field, although it may take more effort in undoing the builders mistakes. One would hope that if the plan is made before construction, the builder would not work against you. If you are coming in later in the game, you have to take measurements, but at least you can start with a plan that has the structures to use as reference points and some benchmark for elevation. It is better than starting off from scratch.

Another requirement in most communities in my area are Certified Plot Plans after the foundations are installed. These are required to be instrument surveyed and the job can not continue until the foundation's location is cerified. That puts the built building on the plan even if the builder did not do it exactly as on the plan.

This is all great info and a great education for me. It does reminds me how much I still need to learn though!

As for Long Island, Nassau County in particular, we don't have a lot of 'middle ground' The lots are either your standard suburban 60 by... which are the majority, or then you have the old Gold Coast on the North Shore where the properties are an acre and up. (Great Gatbsy's West Egg and East Egg, etc)
The smaller properties are the ones that I need to know the basics, how many steps, where to start the wall, how to make sure everything is graded towards the drywell. Overall they tend to be flatter anyway. It is the larger ones that I am now coming upon where I am needing to know what to set the pool at and how to terrace the property and questions like that that concern me.

I see that a laser level is the way to go, so I guess I need to start saving more pennies rather than buy too little of a tool for the job and regret it!
marg

laag, we do a LOT of carpentry and ironwork. Our carpenter is a former cabinetmaker and finish carpenter who works to that precision, so... so does the designer! :)

Marg, best of luck to you. I think you'll be happy with the results of greater accuracy.

marg, please don't take my comments to be an endorsement of laser levels for the types of work needed for landscape design. Nor do I want to discourage it either.

Gee, marcinde, I thought I was close to the end. Now I need to tell folks how you use the rod, why it can work with some equipment and not with other gear, and the possible impact to accuracy.

I have spent some time here talking about issues of precision. Yet landscaping has few places where precision has an impact on the project. Seldom will it matter if the elevation is in error of 0.1 ft.

But if you aspire to be involved with upscale projects or commercial properties, you are going to be working with engineers and architects. You might want to understand the standands of precision they use.

Look at it like this ... sometimes you may be the first one the client hires. If it developes that the client wants a feature that requires an engineer or architect, and there is one you have worked well with before, that is a guy you will recommend. The same thing applies if they are the first one hired. Learn how to make your work product compatible to theirs.

There are good engineers and architects and some that precision will be wasted on. The latter tend to have projects full of change orders, cost overruns, and enough blame to spread around. This is a subject that deserves its own thread.

Earlier I said I was leaving some things out. The method I think marcinde uses to make high rods shots easy was one of them.

Everyone has heard the old saying "Don't change horses in the middle of the stream." There is an old rule of surveying that says don't change rods in the middle of taking levels. What marcinde suggests violates that rule, but with care you can get away with doing it.

It is novel that you can use a saw to cut a half foot off the bottom of a level rod and still use it. If ALL of the shots are made with the same cut off rod there will be no impact to the precision of the work.

Most tall rods are made in sections that telescope into one another. As each section is raised there is a locking feature that keeps the face rule a continuation of the one below it. If all shots are taken to this face rule it will not mater if the zero point of the scale is not at the exact bottom of the rod.

On the backside of the rod is another rule. It is upside down beginning at the second rod segment and is read relative to the first segment. The rule is designed to indicate the total height the rod is extended. Making some shots to the face rule and other shots using the backside is the same as using different rods.

Most new rods will have a close compatabilty of the two faces causing only small errors in the work. If the plastic foot of the rod becomes worn or lost the error increases. Any error from this source is systematic and builds up with each new location of the base unit.

The basic use of the bachside rule is done in the following way. The receiver is moved to the very top of the rod so that the reading point on the bracket aligns with the top surface. There are a multitude of different brackets made for receivers and rods. It may not be possible to lock the receiver at the top with some brackets. Keep in mind if the bracket comes loose and the receiver falls on to pavement you will probably be buying a new one.

To make a high shot, the lock is disengaged between the first and second rod segments and the second one is allowed to telescope into the first until the the reciever is on beam. The backside rule is read and subtracted from the HI in the usual way to get the elevation. It is a fast easy way to make high rod shots. Below is a photo of the backside with the rod lowered in making a shot. The reading is 14.32

{{gwi:46338}}

I would suggest that before using this method that one check for errors. Set the base unit up on a slope and select a downhill object to shoot where the beam will be high up on the rod. Set the receiver to fine precision. Use the backside rule proceedure first and make the backside reading. Then raise all the rod sections to a locked position and set the receiver using the face rule at the same value as the backside reading. When you stand the rod back on the mark the receiver should be on beam.

I can't disagree with any of what you've said, pls8xx. Typically, what I'll do is set up a grid (usually in 10' increments) aligned with the house, then set up the transit and determine where I'm likely to have to switch from front of rod to back of rod. I shoot all the front of rod (smaller #) stuff first, then pick a set point where I can extend the rod for the back numbers, but still reach to move the receiver along the front. Then I can shoot it both ways and know that I'm accurately recording elevations.

There are only a few more things to cover on laser levels, things to consider when you go to buy one.

The salesman will talk about range and precision a lot but there is much more to a good system.

Keep in mind the range of the base unit spec is for optimum conditions. Dusty construction sites or a climate where every morning has a light fog may shorten the range. The range is often given as the diameter of coverage. If most of your use will be on construction sites, do you want the unit set up at site center with heavy equipment working all around it? The precision spec is the error from level for the beam, often at a distance of 100 ft. The error will double at 200 ft. and more over, other features of the system will add to the error.

Many base units have a protective top cover over the beam. This cover is supported from the lower case by legs that can interupt the beam and cause blind spots in coverage. When demonstrating the system the salesman will set up the unit so that the beam will go between these supports to the area where shots will be taken. You should have the saleman turn the unit so one of the supports is in line with a place you can try shots at close to the maximum range of the unit. Then you can evaluate how much of a blind spot that unit has, small in some, greater in others.

Refer to my earlier comments on receivers.

The rod clamp bracket is an important part of the system. Is the receiver to bracket mounting adequate for field treatment and adjustable? If you want to use the backside reading method for high shots, does the bracket firmly attach to the rod at a point where the read point is at the top-of-rod surface? On very long rods, the weight of the receiver plus bracket can be cumbersome, lighter is better.

How much trouble is it to remove the bracket from one rod segment and attach it to another? You may be doing this a lot. Does the bracket easily slide up and down on the rod without coming off? What is the lowest rod reading that can be made?

Some brackets may be universal in type to fit all rods but be a good match for none of them. Another bracket might be well suited to one rod and unusable on other rods.

Rods are made in segments and some brackets will have the highest shot point on one segment that is still lower than the lowest setting for the next rod segment causing a dead spot on the rod. Through trial and error shots, find out how wide the dead spot is.

For relatively flat projects, a 2 section 13 ft rod is a big advantage over a 3 section 15 ft rod. The shorter segments of the 3 section rod will lead to a lot of places where you are in the dead zone on the rod or you will have to move the bracket to the other segment many more times.

I would get two rods, a long fiberglass rod and the 2 segment 13 ft. wood rod, and brackets to fit each.

To deal with dead spots on the rod or shots near the rod segment joints, I would make up a rod boot. A 3 foot slat of aluminum or wood has a block attached to it so that the rod can rest on the block exactly one foot higher. The slat should have the same width as the rod so it will be easy to hold the two together. The 1.0 ft boot distance is added to the rod reading. See the graphic below.

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