Before we start, I’ll be very honest…I’m wrapping helpful advice around promoting our own product. However, all of these points should be serious considerations when looking into BIM take-off. Pulling data directly from a model involves a high level of risk, here are my top 3 points on the subject.
1: Not all quantities are created equal
Models only carry basic measures like area & volume, using these carries a high risk. It’s tricky to convert these to actual measurements likes formwork, tonnage and surface areas. These are the *actual* quantities needed, so make sure your takeoff software can add these measurements easily.
For example, our solution, Cubicost has assessed the walls by material, so concrete gains side and end formwork in the correct stages, rebar weight and concrete volume. For the stud walls, we use the centre line and deduct overlaps to produce accurate quantities that are very different from the quantities in the model data.
2. Play by the rules
Measure rules such as SMM7 & NRM2 have worked for decades to create a level playing field. Applying these rules retrospectively to a model can be infuriating. Be sure to understand what intelligence & tools your software has for this task.
By incorporating these measurement rules into our software, in this example, only some of the openings should deduct their volume from the slab. On a project that has 4033 openings of varying sizes, that’s a big help a significant difference in measure & risk.
3. Don’t be afraid to add value
Showing customers that we can edit IFC and Revit models is often a shock. Getting the job done means adding stuff that isn’t there, especially at tender stage. Being able to add finishes, delete items, change sizes & thicknesses has all kinds of positive implications for estimating & value engineering. We’re not changing the design, we’re using digital red pen.
The most popular example used by customers is the Room feature, used to flood a space with finish detail such as paint, flooring & skirting with a single click.
Thanks for reading, please get involved in the comments and finally, remember to check out Cubicost when thinking about BIM quantity take-off.