Discover the essential role of geometry and meticulous attention to detail in construction estimation. Learn how to account for hidden conditions and ensure that every square foot of every finish and surface area is covered, even when not identified in architectural drawings.
Key Insights
- An estimator's primary tool is a firm understanding of a building's geometry. This knowledge enables them to accurately carry out quantity takeoffs and validate scales to ensure accuracy.
- Estimators need to account for 'hidden conditions' or unmarked areas in architectural drawings. These can include elements like plaster walls around a room, or the inside of a parapet on the roof, which may not be clearly indicated in the plans.
- It is the estimator's responsibility to quantify all areas required to build a project, irrespective of whether the architect provides this information. They may need to refer to multiple drawings, understand changes in ground slopes, and make educated assumptions to ensure a comprehensive estimate.
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One of the primary tools that an estimator has is understanding the geometry of a building. The first thing that I do when it comes to a quantity takeoff is I first validate the scales and make sure they're correct. In reference to the plans, note that if you're inside of the main house and you're walking into this new guest room and music room, this is the image that you would see as an elevation.
We have the curved roof, we have the width of the music room, we have the structure beneath it, but beyond it there are plaster walls that have not been identified with this section. As good as the drawings are, it didn't take into account that the estimator might not actually see that there's plaster that's going to occur on that side of the building around the music room. So what you see in this image is there's additional takeoff information that's not shown on the actual drawings themselves.
Since it doesn't have an elevation, I needed to identify the total area of plaster on the exterior of the building that was not shown in an elevation. Also at the very top, notice that it's a bit darker. I have another takeoff and that's for the other side of the parapet.
My task here is to find out how many square yards of plaster is there, whether it's shown or not. I refer to these as hidden conditions and even if it's not identified in an architectural set of drawings, it's important that the contractor, the estimator, still pick these up. It's our responsibility as estimators to make sure that we have every square foot of every finish, every surface area covered.
So in this case, I took it upon myself to quantify those areas, whether the architect provided them for me or not. If they're not provided, for whatever the reason may be, it's still a responsibility of the estimator to quantify everything required to build that project at a given price. I had to go through a number of certain drawings, including a floor plan, to identify what the total width of that elevation of that view might be.
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On the same floor plan, I identified the width of the walls to the left and to the right of the bridge. I had to look at similar elevations to find out how tall the walls were and where they meet the ground. This was tricky because the slope of the ground changes from view to view.
So it's a combination of looking at other sections that might offer more information. If you look at the longitudinal section, where it goes through the entire music room, guest room addition, into the house, you'll quickly identify what the overall height is going to be. You could relate the parapet in this elevation right here, that you see at the top of the room, with a detail that's also being utilized for the other three sides.
It's safe to assume that the parapet would be no different on this side of the building and therefore plaster on the inside of the parapet on the roof itself should be quantified as the other three sides. That in itself will give you a number of options to choose from to come up with the overall quantities required. So even a construction set of documents may not have all the information required.
Now technically you could reach out to the architect and say, hey Mr. Architect, could you go ahead and provide me an elevation for this? Or you could go ahead yourself and actually figure out what's going to be required. This will speed up the entire process of your estimate and not have to put it aside and wait for a response to come back from your architect. Understand that as we mentioned earlier with estimates or with estimating, it is an assumption based on the information available at the time that you build the estimate.
So even though it's not drawn, it's not shown, there's too many other items within the drawings themselves that clearly spell out what's going to be required for this elevation. So take it upon yourself as an estimator to quantify the areas that are still not shown. Bottom line is, it's a quantification that is identified throughout the entire project even if this one elevation doesn't provide what you need.
