Step 1 - Preparing the takeoff
The first step is to simply locate the roof plan and insert that in the estimating software of your choice.
Always scale the page first and check at least one horizontal and vertical dimensions to verify the scale is set correctly.
Insert the other pages as well. Typically, we will need the elevations and sections later to refine and verify the takeoff as well takeoff items not clearly shown or visible on the roof plan.
Step 2 - Doing the basic takeoff
As a preference I start with the area takeoff of the roof. If the roof has different pitches then each pitch needs to be taken off separately. If the roof uses different materials, then they also need to be taken off separately.
Measure the lengths of the eaves, hips, valleys and gables. All of them need to be taken off separately for different pitches and materials.
A common question is what to do when two different roof pitches form a hip or valley. In general I go with the higher pitch to err on the side of overestimating slightly rather than underestimating.
Next step is to takeoff the roof flashing. Both sloped and straight. Again, separately for different materials and pitches (if applicable).
Last but not least are things likes soffits, insulation etc. If applicable depending on the job and the type of roof material.
I prefer to do the entire takeoff on the roof plan and not takeoff items like flashing or gables / eaves on the elevations. This avoids errors and the whole takeoff can be checked for completeness on the roof plan itself. However, this is a preference and an accurate takeoff can have some elements taken off on the elevation.
Step 3 - Checking the takeoff and notes
You should be looking at all the notes including on the roof plan, elevations, sections and specs before starting the takeoff. However, going through the notes again after the takeoff is finished is extremely crucial.
I would now recommend looking at the elevations simultaneously along with the roof plan. If you have two monitors then perfect. Else take a print out of your roof takeoff and use that.
This step is to make sure that you didn’t misinterpret or make the mistake while doing the takeoff. But also to make sure the roof plan matches with the elevations.
Sometimes, plans can show discrepancies between the roof plan and the elevations. These discrepancies need to be note and an RFI needs to be communicated to the GC or the architect to confirm what plan needs to be followed.
Step 4 - Adding waste and additional items
I have covered in detail how to add waste and how to add additional items in detail in other articles.
In short, anything needed for installation or in addition to the basic items taken off above need to be added.
Also, waste needs to added. Typically, bigger the product, smaller the roof and the more complicated the roof, the greater the waste. And vice versa. A little bit of actual installation experience will go a long way to getting this right.
Also note that materials come in boxes and packets, not in any exact quantity you need. So all quantities including waste need to be rounded up taking into account the quantity per box etc.
Step 5 - Adding labor and margins
While strictly not part of the takeoff, adding the right labor costs and margins is essential to winning bids profitably. Take into account your overheads, productivity, complexity of the job, location of the job etc.Apart from the bid, relationship with GC also plays a big role in winning bids successfully. The quality of your last job and developing positive working relationship with the GC should be your goal on all projects you do win.