As an engineer who also builds, I used to wonder if people asked their brain or cancer surgeon about their margins.
I understand the natural inclination to minimise costs when variations in quotes run into thousands but many customers do not consider the wide variation of quality out there.
As an example, subcontractor plumber/electrician/bricklayer/carpenter/painter etc etc could have different sized crews of varying experiences.
Let's say I am building for clients : one house or two duplexes versus a medium density development of four to six townhouses.
For the former, I'd insist a subby to have no more than one first/second year apprentice with someone fully qualified always onsite whilst on bigger jobs with two per final year apprentice or full ticket. This ensures quality of work. Some crews will have four or five of these juniors per qualified tradesman. If you consider the wage costs between junior apprentices and full tickets, it allows some subbies to be 'very competitive'. In turn, builders willing to use such crews can also be very competitive. Add the number of different trades...thus the large variations. Sorry but if I don't want the business for a reason..I may also hike the price.
Some builders also use more costly methods. For example, I cut the driveway early and pour 50 to 100mm layer of volcanic crush scoria after the house slab is poured plus slab surround. To me. it's a necessary protocol. Cleaner safer site during works and better driveway for the client. That could run into a few thousand dollars sometimes so I have to allow such. Most single house builders will not. Factory frames no longer consider stud channels necessary so I attach periodic stops to top and bottom plates despite it being 'unnecessary' because it is simply outdated secondary insurance due to modern timber ratings. Possibly only needed once every thousand times. One days extra work for only 20 dollars worth of timber. But priceless peace of mind. There are one or two others deemed good practice but also others which I'd say horses for courses.
These are the same factors for ANY business in any industry. Costs versus pricing.
But as the final occupant or developer who onsells, are you willing to take the product risk ? Fancy sleeping under a questionable ceiling ?
I have seen all sorts of rubbish put up by cheap subcontractors and am unwilling to use such.
Without adequate compensation for the builder, you risk hundreds of thousands to save a few thousands by using substandard. A builder with a normal margin will be willing to overpay a subby to ensure a good or timely job because there is scope. A builder with a razor margin will be forced to wait. Reality bites.
I was lucky to have been taught by an old hand and am lucky to have customers who can see my reasonings.
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Go out and get a few quotes but more important is to ask for references from jobs within one year AND four to eight years ago.
Go look at the jobs. Then pick the one that makes the most sense.
Job faults within the first year tend to point to poor finishing or improper application according to the building code.
Job faults within the later period point to structural inadequacies.
A cheap quote could cost you a bad build as well as costly delays if you owe the bank.
Good builders willing to do cost plus will be 20-30% job dependent.
Most good builders who quote fixed price will be similar because they have to compete.
If your job is very specific or out of norm then expect large variations because of uncertainties and differences in skillset.
Good luck and regards to allquest