After you add your plans to a project, or create blank pages to use with a digitizer, and before you draw any takeoff (measurements), you must set and verify the Scale on each Page.
Scale is an indicator of the relative size of your drawing to the actual building object. So if you draw a line that's 1" on the screen, it represents, say, 10' on the plan.
Scale is usually listed on the blueprint or plan, often times in the title block of the page - but do not take the listed Scale as fact, always verify.
Why Is It So Important that I Set and Verify Scale?
Setting and verifying the scale for each page in a project before starting takeoff is of utmost importance. Because Scale affects the Results of every piece of takeoff you draw, if a Page's Scale is wrong, your Results will be wrong.
Think of it this way, if you used an estimator's ruler to calculate the takeoff on paper drawings but used the wrong side of the ruler, you're measurements would be wrong - this is no different that an incorrect Scale.
Even minor discrepancies in Scale can add up to significant errors in your results - you could very easily over- or under- estimate your survey.
I Set a Page's Scale to What Shows on the Drawing, I'm safe, right?
Not always.
Even if a page indicates a particular scale (on the drawing itself), you must verify that Scale to make sure it is accurate. Even a small discrepancy in Scale can affect takeoff quantities - especially as a project gets larger and you draw more takeoff.
You may ask yourself, "How could the Scale shown on a drawing be wrong?" - That's a great question! The answer is... it all depends on how the drawing/plan was saved/created. Was it saved to the correct page size to make the Scale accurate? Was it a scanned copy of an original, paper plan, and did the scanner distort the Scale? Was the Scale accurate in the first place? Did the Pages dimensions change at some time effectively invalidating the scale listed on the drawing?
Anyway, in the next few articles, we cover Setting, Calculating, and the most important step, verifying the Scale of your drawing, before you do anything else!
Setting and verifying Scale literally takes seconds but failing to do so can produce
takeoff results that are inaccurate.
Notes about Scale
- Every Page in a Plan Set may have a different scale - that's alright and not expected - that's also why you have to verify the Scale on every Page before drawing any takeoff or annotation.
- Each page can be assigned only one scale.
- If you come across a drawing and there are several regions on that drawing that have been drawn to different scales, you must duplicate the Page and set each copy to a different scale. See OST - Handling More Than One Scale on the Same Plan for information on how you can accommodate multiple scales on a single drawing.
- If you come across a drawing that has a different vertical versus horizontal Scale, you will not be able to use that drawing in On-Screen Takeoff. You can contact the architect or plan provide and ask him or her to produce a single-scale drawing.
- We do not recommend drawing takeoff and then changing the Scale. On-Screen Takeoff may not be able to resize all takeoff objects correctly. The new scale may cause some takeoff to extend outside the page or there may be objects that cannot be resized because of related or connected objects.
- It is vital that you set/calculate and verify the scale on each page before drawing takeoff.
If Page Scale isn't listed on your drawing, don't worry, On-Screen Takeoff can calculate the Scale based on a known dimension shown on the drawing, see Related Articles.
Let us start with the simplest process, setting the Scale based on what the drawing shows you.
Scale and Takeoff Overview