How to survey a crooked house

Hi Everyone,

I have to survey and draw up a set of plans for a building that has a number of walls out of square. What's the best way to do that these days.

Anticipated answer 1: "I choose a wall to act as the Datum x and Y axis and then run my measurements off these."

Anticipated answer 2: "I set up a couple of laser lines and work everything off these"

Aniticipated answer 3: "there's some app that does it for you automatically - didnt you know"

Short answers:

1. can work. Have done it.

2. can work. Have done it

3. No apps that magically do that, unless you happen to have a Leica HDS 3000 Terrestrial Scanner or something similar in your pocket. At any rate it ain't workin' with the LT version of AutoCad.

The long answers.

I use a combo of 1 & 2.

It depends on how complicated the building is, and what the survey data is to be used for. My usual purposes are to design and let the field guys build in shop, then install custom wall panels, floor to ceiling shelving, kitchen cabinets, and casing and moldings like baseboard, chair rail, crown, and wainscot. For the molding work, I don't care how square the rooms are. That's up to the finish carpenter. for the cabinetry and wall panels, it can impact the way the cabinets are designed, so I have to know if there are any grossly wacked out walls. The way those are usually dealt with, is to leave a couple inches at either end for scribing a narrow trim strip to the out of shape wall.

I have a small level with a laser in it, an infrared distance measuring device, and an old fashioned plumb bob on a 20 foot length of mason's chord. Not one of them cost me more than $30.00 and They are invaluable. I sit the level in the floor and locate the highest corner of each room by scanning the red line it throws all around. One always levels cabinetry starting at the high point and bring the rest of the run up level with it. One cannot dig a trench in the floor or leave the beer mug to slide off the counter.

If I have to, I can measure up and down from the red line once I put the level in the high corner. I usually only care about one or two rooms at a time. I have not had to deal with an entire structure. I can also shoot a plumb red line up the middle of a wall and measure the adjacent walls off that line at the floor and ceiling. If you do that a couple times along the common exterior wall of a series of rooms, I suppose that could give you a picture eventually of a whole building.

The level also has two spikes I can deploy to stick it to a plaster, sheetrock or wood wall surface, shoot a level red line along the more or less middle of the wall so I can measure the levelness of the floors and ceilings at the wall.

The infrared distance thingy is only accurate to 1/4" over 100 feet, but that is close enough. The old saying that "there is nothing smaller than 1/8" in the field" is more true than anyone thinks. besides, no matter how hard one tries to be accurate measuring as-built conditions, the measurements are not ever going to be any closer than within 1/4" accuracy anyway.

I also try to locate, or measure to a point on the end of a wall or breakfast bar that stops in the middle of a room, from at least two previously located points, triangulation, a good technique to use.

And further more...

There was a crooked man and he walked a crooked mile,

He found a crooked sixpence upon a crooked stile.

He bought a crooked cat, which caught a crooked mouse.

And they all lived together in a little crooked house.

Use the old fashioned 3 pts and yes adopt 1 wall then measure the diagonal and side wall, repeat for the two corners. Like Dana put a block at top of wall and drop plumb bob will tell you how much out of vertical.

Thank you Dana for your detailed advice and humorous limerick. Thanks also Bigal. I am faced with quite a large floor plan with a number of walls out of square.

I'm hoping I can you use diagonal measurement to get the angle and then somehow repeat with the opposite corner.

I would like to go in with a smart laser system set up some grid and then take all the measurements from that.

Can you get to the outside of the building, all the way round? Sometimes an external survey can give the shape of things inside. Window openings can be useful.

If you do not have a theodolite, then diagonal measurements and overall lengths are good. Draw the plan at floor level. Usually internal walls are parallel each side.

Is the house going to undergo a complete, top to bottom, renovation? Will the walls be gutted?

If using a base line line look at getting a Optical square its old fashioned but allows a reasonable sq off for improved accuracy.

There is an app that works with LT and a laser measuring device, such as a Disto. It comes frm a company called kubit from Dresden in Germany and the app is called DisToPlan and is intended for professional use. http://www.kubit.com It's not cheap but will soon pay for itself if you need such an app a lot.

Ben

Apologies for the delay in replying

The building is a large restaurant but with lots of internal walls doing all kinds of things

The Kubit Software looks very interesting gb.kubit-software.com

I've done lots of similar surveys and the best method that I've found is 3D laser scanning. We surveyed a complete medieval castle, including the cellar which was hewn out of rock, all the rooms on three floors, the roof space and the external facades. We were done on site in three days and modelled it up for the architect in 2D, in no time at all. The laser scanner and software were rented for very reasonable rates. End result? The job was complete in a fraction of the time as when we had used classical methods and for significantly less cost. Kubit also do software for laser scanners which is far better than that of Autodesk. It also has automated pattern recogntion, which can identify walls, beams, stanchions, pipes and fittings, etc.

Think about it for your next job.

I would have so much fun doing a project like that, Tyke. Was it as cool as it sounds?

I would have so much fun doing a project like that, Tyke. Was it as cool as it sounds?

No it wasn't as cool as it sounds, it was so much better than that . Seriously that was the first big laser scanning job that I did and it really got me hooked. I'll sort out a few photos and post them later today. Afterwards I did a technical presentation and the audience were absolutely overwhelmed with it all, I even got a four minute standing ovation at the end. We did a few other castles and old buildings, but not on the same scale.

A standing O! I've been on stage before but have never gotten one of those. That must have been awesome.

Yeah, a few pics would be cool.

OK Rob a few pics to show how it was. We used a Trimble laser scanner and software to work up the 3D scan data and then exported it out to AutoCAD, You can see how the walls floors and ceilings were not straight nor level. All the data is still there in 3D and it would be possible to go back and produce more drawings from the existing data. The data from the cellar was the most interesting and if you look very closely in the scan data from the cellar room you can actually see how one of the surveyors got scanned. I've also included some scan data and photos of the same place so you can see how well the scan data fits reality. In the cellar room you can actually see the electricity cable. The colours in the scan data come from the strength of the reflected signal, on this job we didn't do coloured scans, but we did on subsequent jobs using a different scanner.

Cellar plan

Scan data from a cellar room

Scan data for the whole cellar

Building cross section

Building long section

Floor plan 1st floor (UK)

Elevation in AutoCAD

Elevation scan data

Roof space photo

Roof space scan data

Room photo

Room scan data

Yeah, very cool stuff. Thanks for sharing.

Yeah, very cool stuff. Thanks for sharing.

You are more than welcome Rob, glad you liked it.

It would be worth looking into the feasibility of hiring a laser scanner on a large project like a factory survey.

For my everyday tasks I'm going to take away the advice of two straight edges

and the diagonal measurement between the two points. (longer the better)

p.s Does anyone use the Starrett site protractor?

Very cool indeed Tyke. Would it be possible to get access to larger images of the ones posted?

I presume that is just the weekend cottage, where do you live normally? any photos of that.