Best practices for documenting a house's floor plan

OK I’m a long term IT pro, so pretty technical but SketchUp is a new thing outside my core area of expertise.

Trying to document our rather complex house floor plan, I find myself down a rabbit hole, and think I need to step back and re-analyze my core practices or approach.

I’ve watched quite a few videos so get the main functionality and features of SketchUp (just still a bit confused on managing groups vs. tags).

I’m wondering what folks here would recommend though.

I started by measuring the outside of the house. Then moved to try to document the inside rooms. Nothing in this house lines up very well (lots of remodels have happened over the years), so it’s quite a challenge.

So now I’m thinking of scrapping the whole thing and doing the opposite approach. Ignoring the small detail differences and drawing out the internal rooms in rectangles only - working from the outside in - because I ran into many problems moving from outside to in - lots of measurements were wrong and I was constantly adjusting walls. Which would affect the next wall, and the dominos kept falling.

What is the best approach? And mainly - when I measure rooms beside each other how do I piece those together and account for the thickness of the walls? For example I can measure two rooms next to each other, but I can’t put those rectangles exactly together because if I push/pull I’ll rob Paul to pay Peter, or vice versa. And similarly, how do you deal with baseboards? Do deduct 1" here, a 1/2" there?

I think perhaps if I get these core principles understood, it’ll be easier going forward. And if anyone has a recommended UDemy course for this specific kind of thing, that would be great. The goal is to: draw out the layout of the house, and use this framework as a thing to assist with potential remodel ideas (in 3D). I also have to deal with a 2nd floor - and I’m not sure how to handle that either!

So many questions but thank you for your advice. This community and group here is very helpful!

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Have you considered hiring a professional…?

Seriously, the thought of thinking how best to adequately advise you on how to go about this makes my head spin.

Perhaps also a course in basic architectural understanding and drawing if such a thing exists?

A few YouTube channels you might already know of…

There are two separate tasks here: one is the surveying, the other is the recording (by making a SU model).

Taking a measured survey of a building is a subject of its own, but essentially you need to start with a reasonable sketch of each floor plan. This should show walls (represented by a double line so you can measure thickness), openings (windows and doors mainly), steps, and (possibly) downstands. There may be other more unique features you need to record, depending on what you need. But don’t try measuring everything. Details generally don’t matter.

If you want accuracy, you need to take diagonal measurements too, but most spaces are sufficiently square not to need that. You may also want to record critical heights, such as window cill heights, heights of changes of level, and ceiling heights.

Now you can transfer the data onto your virtual model in SU. The benefit of doing that in the building you are drawing is that if you made a mistake with a measurement or left out a critical one, you can easily go back and check it.

As for the model itself and how it is organized, everyone will have their own way. Personally, I start by laying out the walls on plan. That should create a series of closed loops enclosing surfaces. You can then Push/pull them up to show the room height. I do each floor separately but on top of each other. Then I make the floors and roof as separate entities again. At that point, you may want to start adding detail like windows and doors. Some people prefer to separate out internal and external walls.

This describes almost exactly my method: Measured Survey 101 - How to measure a building with ease


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Link from Simon to First in Architecture is an excellent one - great site.
See comments below in that link as well including suggestion to take photos.
Remember drawings are representational and can be to many degrees of accuracy whilst buildings are reality and can deviate in all directions. You sometimes have to compromise and approximate and then allow for a degree of tolerance in design. Nonetheless aim to be as accurate as ‘reasonable’.
I tend to try and work from some key reference points and work back to those.
Remember what is important and identify critical dimensions. That can be tricky as the emphasis can change during design process.
‘All dimensions to be checked on site and discrepancies reported back for clarification’ and suchlike.
Its a tough one.

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One other small point may be worth adding about accuracy.

CAD offers the ability to be very accurate indeed. You can happily work to tiny fractions of an inch in the virtual world. But in the real world of construction, it is only worth being accurate to the kind of tolerances that builders would work to. In Europe, that often means 5 or even 10mm. In the US, I guess that would translate to between 1/8 and ¼ inch. So there is little point in taking measurements any finer than that.

Because spaces are almost never perfectly square and the process of measurement itself is somewhat imprecise, you will often find that you cannot “close” a loop successfully. I mean that you can take every measurement around a room and find that the meeting point does not in fact meet. Most of us would then just “fudge” it, unless the discrepancy was very big.

Ultimately, you need to tailor what you do to what is necessary. You don’t need NASA type tolerances for most building projects!

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This is pretty well done! Much like what I do, but I usually don’t bother with diagonals for the types of houses I do

You can never know with people. Long ago, I measured a log house and presumed it to be rectangular as it was not visibly skewed. But it was, across the room the deviation from right angle amounted to about 100 mm. The wall was to carry kitchen cabinets. As I was not present, the builders resolved a problem that would have required two strips of wood to fill the gaps at the ends by building an extra layer of wall to make the whole thing rectangular, wasting a bit of floorspace and a lot of work.

Good point. I think I would look at diagonals in a log house or if there was something special about the shape. Most houses I measure are built fairly square and the contractor can deal with little Inconsistencies so I don’t “usually" bother. But yeah! I’ve measured stone buildings that were built to the property line (or railroad tracks) and not to any square plan at all.

My example, I think was “fairly square” too. 100 mm at a distance of over 4 meters is IMO not a big deviation (my image is exaggerated). Of course it would have to be taken care of if you wanted, for instance, to cover the floor with tiles.

The center of our third largest city is built on a gridiron plan, the property lines laid down in the late 1700s. The gridiron deviates less than a degree from 90 degrees. In some places you see odd results of cramming a truly rectangular building onto a lot.

I carry my laptop to the house and create the 3D model as I measure. I bought a laptop stand which makes it easy to move around through the rooms, as well as outside. I use a Bosch laser measure, 100 foot flex tape and a 30 foot conventional tape measure. For calculating roof pitch, if I can’t physically reach the roof, I use the Pitch Gauge app on my phone. I’ll take additional notes such as stair rise and run, soffit depth, floor depth, siding exposure, etc. I also take a ton of photos.

It normally takes my wife and me 2-3 hours to measure a house and create the as-built model on site. I then spend another 4-5 hours adding details such as roof, decks, porches, etc.


This makes me wonder whether there is a reasonably affordable app that would allow, say, a laser measuring device to communicate with it and construct a plan on the fly. If not, maybe some clever techie might think of creating one?

Leica have an app for some of their devices that connect via bluetooth.

The reviews were poor and the Android app has been temporarily withdrawn.

I did try to use it once and wasn’t especially impressed. The paid for version had more functionality and I might have paid if the app was better.

I have to say that I like @munionman method of the laptop stand and producing the 3D model on site.

I could imagine myself with a tablet on a stand using an improved Leica app and the bluetooth connection to the laser.

And I can imagine having a special halter type sling for a laptop or tablet worn around the neck. If you could couple that with a Bluetooth laser measuring device, you might never need pencil and paper (and eraser) ever again!

I would prefer a young assistant springing around with the measuring device and shouting to me the dimensions. Two can measure a house in 1/4 of the time it takes a single person.

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Sure. But what would the springing young assistant cost?

I might cost, say, 30 Altairian dollars per hour.
The assistant costs 20 Altairian dollars
The measuring takes me 4 hours alone = 120 Altairian dollars
It takes us two 1 1/2 hours ( a bit more pessimistic than my previous post)= 75 Altairian dollars.

Looks like they do have an app but not sure it is for all platforms. The SmartPlan looks as if it may be a little too ambitious.

I saw a review that said the Bosch version is actually better. The whole setup is also way cheaper too. In fact, so cheap I might be tempted to invest just to road test it. Use it with the iPad App! Bosch Professional GLM 50 C Bluetooth Laser Measurer & iPad app DEMO - YouTube

I have yet to see a full floor plan. It all seems to be based on doing a single room at a time. That may be fine but it does all have to knit together at the end.

This is an update to my last post.

The limitations of the Bosch system are covered here: Transferring measurements from Bosch to SketchUp in dwg? - #2 by db11. The main problem is that it only exports in non CAD formats.

There are apps like MagicPlan that seem to bridge the gap by allowing you to use almost any Bluetooth enabled measuring device to create floor plans. But you may have to be doing it quite a lot to justify the monthly subscription.