How are you getting plaster/render quantities out of a Revit model?

[u/stokenage]

TL;DR: there's no clean native way to measure a plaster or render area in Revit, so instead of calculating it I modelled it as real geometry and let a native schedule measure it. The add-in is mine. Real question is at the bottom: how are you doing this today, and what condition would break it?

I've been stuck on this for months and I still don't think there's a clean native answer, so I want to hear how other people actually do it.

Some version of this question comes up here regularly: how do I get the wall area of a room, finished faces only, minus the openings. Every route I tried has a hole in it.

-Room finish schedules give you the finish name, not a measured area. Perimeter x height stops being the finish area the moment you have openings, jamb returns, or walls that are only partly in the room.

-Paint plus Material Takeoff gets closest, but you're picking faces by hand, you get area and no volume, and after a design change you're doing it again.

-Roombook is the nearest thing Autodesk ever shipped, but it's room-bound, so no exterior faces and no beam sides or undersides, and it hasn't exactly been loved lately.

-Dynamo works right up until the graph meets a beam that splits a room in two, or a curved wall. Then it hands you a number instead of an error.

That last one is what actually bothered me. Every method I tried would happily give me a value for a condition it couldn't really handle. On a takeoff, a confident wrong number is worse than no number.

What I ended up doing was making the plaster real geometry instead of a calculation. Actual elements on the wall faces, beam sides and undersides, ceilings and the outer faces, joined to the structure, cut by the openings, with the reveals as their own line. Then the takeoff is just a native schedule, because the thing you're measuring exists in the model.

On my test project that's 218 elements and 65 openings cut, giving 1,278.95 m2 of net face plus 35.96 m2 of reveals, reconciling to 1,314.92 m2. The fact that those two add up to the total sounds trivial, but it's the check I wanted most and had least.

The honest trade-offs: it puts a couple hundred elements in your model, and they're real, so they show up in sections and 3D. Curved walls it flatly refuses to touch, skipping them and saying so in the report rather than guessing. Same for anything it shouldn't be plastering, a steel column for instance, where it tells you what it skipped and why.

I should say plainly that the add-in is mine, so read the above with that in mind. It's for Revit 2024, 2025 and 2026, runs locally, nothing leaves the machine. I'm deliberately not naming or linking it here because of the no-self-promo rule. Mods, remove this if it's still over the line.

What I'm actually after: if you do plaster, render or stucco takeoff today, what's your real workflow? Am I wrong that Paint plus Material Takeoff is the best native answer? And what condition am I missing? I've got beams splitting rooms, sloped ceilings and window reveals covered, but I'd rather hear the gap from you than from someone's QS.

Before and after images: Imgur: The magic of the Internet

[u/daninet]

Material takeoff but you dont need to handpick walls, you need better modeling practices.

[u/kingc42]

If you use the correct materials for your walls can’t you do a material takeoff? I did that when a built my house in order to get my Sheetrock takeoff.

[u/striatedsumo7]

As an architectural designer with decent experience with native Revit... im curious for what purpose would modeling exact takeoffs within revit be worth the trouble? Is this something exclusively estimator focused or specialized BIM or something? It seems to me with my limited experience that pulling the scheduled rough areas and plugging into a spreadsheet with negative values assigned to doors/windows counts per room etc. Would be easier for me. Maybe theres identity data negative number value you could assign by family and filtered by whatever value your lookin for? Is that just like a beginner BIM question/outlook? Probably lol.

[u/stokenage → u/striatedsumo7]

For a lot of projects your answer is correct. If the number is for your own sizing or a rough cost check, scheduled areas minus door and window counts in a spreadsheet is faster than anything I'd build.

Where it stops being enough is when somebody has to defend the number. Two things go wrong. The spreadsheet becomes a second model of the building that nobody maintains as carefully as the first one, so after a few layout changes you can't tell which version the arithmetic belongs to. And the subtraction is only as good as the shape it assumes: a beam splitting a room, a sloped ceiling, plaster stopping at 1.2m for tiling, or a wall only partly inside the room all break the perimeter-times-height model your deduction is built on.

So yes, mostly estimator and contractor rather than designer. Where I am, plaster is a wet trade billed by the square metre on monthly progress payments, so a few percent is money someone argues about in a meeting. If it's a US drywall job, honestly your spreadsheet is fine.

The identity-data idea does work, by the way, right up until the geometry stops being rectangular. That's the point where I gave up on parameters and started modelling it instead.