When designing a fire alarm system for an existing structure, often times you may come across projects that require a floor plan layout to be drawn before the actual fire system design can be done.
In most cases you may be fortunate enough to receive a hard copy scaled floor plan from the customer, contractor or engineer and in other situation this may not be the case.
If this happens to be the situation you found yourself in, chances are that, what we’re about to share with you will drastically improve the time spent designing your client fire alarm system or whatever retrofit project you’re working on.
Scaling imported floor plans in AutoCAD
The first thing you want to do is import the scanned drawing file in TIFF, JPEG or PDF and then traced the layout in AutoCAD. After you’ve finished tracing the layout it need to scale to its correct size or “real world size” depending on what type of layout you’ve received from your client.
For an example, let’s say you’ve received an unscaled floor plan on an 8.5 x 11.0 sheet of paper and that is the only document available for the building you’re contracted to design the fire alarm system for. This can be easily recreated once you’ve performed a survey of the property and documented the length and width of the building.
This data collected from your site survey along with the unscaled layout can then be used to recreate an accurate layout to begin the fire alarm design.
Now measure the dimensions of length on the drawing you’ve traced in AutoCAD and compare the difference between that of the field dimensions. You should notice immediately that there is a significant difference between the two sizes.
Determine the scale factor
Once you determine the difference length between the field measurement and the traced file, use the following calculation below to arrive at the desired scale factor. Note: Be sure to replace the measurements with actual ones from your survey and traced drawing.
- Field or hard copy file: 52 feet.
- Traced file you’re redrawing: 32.5 feet.
- Divide 52 feet by 32.5 feet = 1.6 feet (scale factor)
With the scale factor achieved, all you need to do now is scale up your drawing 1.6 feet to get the actual size of the layout.
