how does everyone deliver quantity data?
is it just in Archicad?
do you use an estimator?
how long does it take for someone to quantify a plan?
i realize these are super generic, but im just trying to get a feel for how much time is spent doing these things.
my current template allows me to quantify everything in a plan in minutes. so i want to find out how others achieve their estimating goals.
Quantities solely based on computer data is not fully relied on by me and many others who have done many accurate quantity take offs and a full materials list.
The computer program can assist the process but you should go through your material take offs with a fine tooth comb. Take offs should be done from full construction drawings and documents including any engineers drawings of the structure.
You can however do an estimate within minutes if you have a pre set construction method and have a good idea of your company’s construction costs. If you have been doing estimates or quantity take offs for a company for many years you can use a square area rate as a guide before doing an accurate materials list take off. Provided of course the design is similar to one you have done before.
If your building is highly sculptural then labour rates can be very hard to gage as well as the time taken to build a complex building.
As for the time taken, “how long is a piece of string?”. I personally wouldn’t extract my data from my CAD drawings and send that to others for an accurate take off. I would do as I have stated above.
Yet others here may have a different method and use other software to help them through the process ?
If you have ever watched the TV series “Grand Designs” you will see how far some are out with their construction estimates. Yet when they engage professional quantity surveyors the costs are usually more realistic.
I have done quantities for more than a thousand houses with methods above and without the use of cad software when I first started.
I am retired from quantity surveying these days but I still do working drawings for houses now and then.
No at worry, you have to be bit on the pedantic side with quantities. That’s why I was always asked to do more quantity surveying and sub contracted out the drafting work when we had a full load to build. I won’t do it now because I am older and more forgetful. I am happy to just design and model up these days when I am asked to.
All the best with your add ons business.
A few thoughts from my experiences (non-residential type projects) working with estimators on our teams, including project budgeting as well as material quantification:
a. Tend to do their own take-offs (e.g., using On-Screen Takeoff or in-house proprietary software), due to their role and responsibility (and knowing what they are looking at may have errors). However, appreciative that there are schedules to act as a check for their work.
b. Scaled plans, sections, and exterior elevations, including roof PDFs (with scale legend) are very, very helpful to quickly set up for estimating. If the project has renovation, it's very helpful to have the existing, demolition, and new clearly defined so as to 'tell the story' and have as background for their (digital) take-offs.
c. Spreadsheet out-files with descriptors (as well as BIM quantities) are also useful to avoid having to re-type off-standard pick list data. Spatial data may also help as some early schematics are costed by square foot (though there is a trend to use the BIM unit data to push to ROM unit costing earlier in concept development).
d. Site PDF including logistical constraints or key resource information (e.g., narrow access, key utility runs and points, clearances, etc.) to be noted are also helpful for estimating GRs and so forth. Of course, a hardscaping/landscaping concept in PDF is good early on at least to project cost intensity (sometimes left till late and found to be wanting!)
e. Depending how your project is set up, a conceptual sequencing schedule is also helpful.
Some of the above may normally be initiated by the GC, but more and more we are looking at integrated project teams who want to identify budget and cost risks asap.
Oh, I should add that over the past two years, I've seen a trend for GCs asking for the AOR's BIM model for their estimators to pull into a 3D estimating, sequencing, and logistics planning environment.
Once we've finished the building permit phase of a project, we will make a detailed budget / building cost calculation in Excel. We have (online) 3rd party documentation for building costs (which includes costs for materials and labour) that we refer to. This can vary from cost per unit, to volume, to surface, to length. We grab the values from Archicad with schedules. Ussually filtered by layer / classification. The Excel sheet follows the same classification. It is much quicker to generate a small schedule, than having one big schedule that pulls all the numbers from a project. It also takes a long time to look up the values you want, if the schedule is too big.
We are generally within 5%-10% of the winning bid if we invite multiple contractors to calculate costs for a contract bid. Our contract documentation includes detailed specifications following the national standard (very detailed), this is written in separate software, so the contractors can make a detailed and specified bid.
It helps if you have projects built once or twice a year at the very least to stay in touch with market trends for costs.
For initial phase we have a list volumic costs based on the gross volume of the project, that differ per type of building, complexity etc. These work relatively well for determining initial budget.
Edit: to add for anyone who will ask "why can't you do this all in Archicad, you shouldn't need Excel": it is very easy to generate data in the excel sheet, based of values pulled from Archicad for things you did not model. For example if you calculate the surface of a window in excel by inputting width and height, instead of grabbing the surface area from Archicad, it is now very easy to also get the length value of any trim made around that window, without having to actually model it.
It’s definitely not too hard to create your own Excel spread sheet, like I did back in the past to highlight all the cost areas and the calculation formula’s to use. I also used that as a checklist so I don’t miss anything. You have to update your spread sheet now then too.
I used a cad application to draw all my construction drawings for accurate take off. I check the data in the cad application but I still do my calculations manually. That’s because the model we design may not always be what is built in the actual real world. Even if your model is almost perfect, you should still go over everything so you don’t miss anything.
Then I will still ask the construction supervisor to check my spreadsheet to see if I have missed anything. They and we usually have allot of experience and know if something doesn’t seem right in the calculations. I always check my Excel specific categories with a square area calculation because I have a very good idea of what each area of construction will actually cost to build.
If you work with a builder and they get the job you should be able to check with them if your quantities are line with the actual building costs. So overtime you will be more and more accurate and more confident about the actual construction costs and putting in a tender.
If you err a bit on the side of OCD it does you good in this profession and in any form of accounting.
Programming a spreadsheet is definitely not as hard a coding an Archicad add on like roof ridge capping etc etc etc.