Two erection bids for the same tower can land far apart and both be honest. The difference usually isn't margin. It's what each sub assumed about the structure, the site, and the schedule. If you're a GC, turf vendor, or owner's PM reviewing bids, the useful question isn't "is this number low or high" but "what did they assume to get there."
This article walks through the factors that actually move an erection scope. There are no price figures here because they'd be wrong for your site. What you get is a checklist for sanity-checking a bid and finding the gaps before they turn into change orders.
Structure Type Sets the Baseline
Everything else scales off what's being built. A self-support tower, a guyed mast, and a monopole each demand different crew skills, rigging methods, and sequencing.
Self-support and guyed structures
Lattice self-support towers have a lot of pieces: legs, diagonals, horizontals, bolts, and plenty of bolt-up hours at height. Labor hours climb with piece count. Guyed masts add guy wire installation, anchor work, and tensioning, which means more survey and more precision on the ground as well as in the air.
Monopoles
Monopoles go up in fewer, heavier sections. Fewer bolts doesn't mean less cost. Each pick is heavier, flange alignment is unforgiving, and the crane requirement usually jumps. Ask the bidder which structure type they priced and how the labor and equipment split changes between them.
Section Count and Weight Drive Equipment
Heavy picks are where a bid can quietly diverge from reality. Section count and individual section weight determine how many lifts you need, what crane capacity is required at what radius, and whether the job is stacked with a crane or built with gin pole methods.
A few things to check in the bid:
- Heaviest single pick and the radius it's made at. Crane capacity drops fast as radius increases. A sub who priced a smaller crane than the lift plan requires will be back with a change order.
- Number of lifts. More sections mean more crane days or more gin pole cycles.
- Top-section and appurtenance weights. Lightning rods, platforms, and pre-mounted gear change the final picks.
Any of this should tie back to a rigging plan. If you want to know what to ask for, our piece on ANSI/ASSP A10.48 rigging plans covers what a GC should require from a subcontractor before the first pick.
Access and Site Prep
Access is the cost factor that gets underestimated most often, because it's invisible on a drawing set.
Getting equipment and material in
Soft ground, a long or narrow access road, tight turns for flatbeds, and low overhead lines all affect which equipment can reach the pad and how deliveries are staged. A site that needs matting, road improvements, or a smaller crane with more trips costs more than a site where trucks pull right up. Ask whether the bid assumes the access is already in place and who owns it if it isn't.
Laydown and staging
Stacking needs room to lay out sections in pick order. A cramped compound forces re-handling, extra trucking, or off-site staging. Rooftop and urban-adjacent sites are the extreme case, where laydown is limited and every pick is a scheduling exercise.
Foundation and compound readiness
Erection can't start until the foundation has cured and passed whatever testing the engineer requires. If your foundations and concrete scope runs late, the erection crew either waits (standby cost) or demobilizes and returns (a second mobilization). Clean sequencing between concrete and steel protects you from both.
Crew and Equipment Mobilization
Mobilization is the cost of getting qualified people and the right equipment to your site and set up to work. It's separate from production labor, and it varies with distance and complexity.
Things that drive it:
- Distance from the crew base. Travel time, per diem, and equipment hauling all scale with miles. A sub with operating bases closer to your site has a real advantage. Kelvan Group dispatches nationwide from Philadelphia, with additional bases in Florida and Colorado, and distance to site is one of the first things we look at when scoping a job.
- Crew size and composition. Stacking, rigging, ground support, and a competent person on site all need to be accounted for. A bid that looks thin on headcount may be assuming the schedule stretches.
- Equipment specialization. Specialized cranes, gin poles, and hoists may need to be sourced and hauled in, not pulled from the yard.
- Number of mobilizations. One continuous visit is cheaper than two or three. If the bid assumes a single mobe, confirm your site readiness supports that.
Field certification and insurance also factor in. Crews should be field-certified, and the sub should carry coverage that matches your contract. Kelvan Group is licensed and fully insured, with general liability at $1M per occurrence and $2M aggregate, a $5M umbrella, statutory workers' compensation with $1M employer's liability, and commercial auto liability. Whatever sub you use, compare their certificate against your contract requirements before award, not after.
Weather Windows and Schedule Risk
Wind is the big one. Crane and gin pole operations have wind limits, and lifts stop when conditions exceed them. Lightning stops work at height. Cold, ice, and extreme heat affect crew output and safety. Depending on region, this shows up very differently. A Gulf Coast or Texas job has to account for storm season and heat, while a Colorado job may face wind and winter access issues.
How a bid treats weather tells you a lot:
- Does it include weather days, or assume perfect conditions?
- Who pays standby when the crew is on site and can't lift? Get this in writing. It's one of the most common disputes on erection scopes.
- Is the schedule tied to a carrier or turf deadline? Compressed schedules often mean overtime, extra crews, or both.
A bid with no weather contingency isn't cheaper. It's just missing a line you'll pay for later.
Reading a Bid: Questions to Ask
When two bids differ, go through the same short list with each bidder:
- Which structure type, section count, and heaviest pick did you price?
- What crane or lift method are you assuming, and at what radius?
- What site access and laydown conditions did you assume?
- How many mobilizations are included?
- How are weather delays and standby handled?
- What's excluded: foundation work, antenna and line installation, fencing, closeout documentation?
That last question matters because scope boundaries are where bids look different without being different. If erection is priced alone, make sure the handoff to antenna and equipment installation and the closeout documentation are accounted for somewhere. For more on screening bidders before award, see how to vet a tower subcontractor in our vetting guide.
FAQ
Why do two tower erection bids for the same structure differ so much?
Usually because of different assumptions, not different margins. Crane size, number of mobilizations, access conditions, weather allowances, and scope exclusions all vary between bidders. Ask each one to state its assumptions and compare those before you compare totals.
Is a monopole cheaper to erect than a lattice tower?
Not automatically. Monopoles have fewer pieces and less bolt-up labor, but the sections are heavier and typically need larger crane capacity. Lattice structures shift cost toward labor hours at height. The answer depends on the specific design, site, and lift plan.
What's the most common cause of erection change orders?
Site conditions that weren't in the bid: poor access, limited laydown, a foundation that isn't ready on the mobilization date, and weather standby. Pinning down who owns each of these in the contract before award is the cheapest fix.
Next Step
If you're pricing an erection scope and want a bid that states its assumptions clearly, send us the site details and structure info and we'll scope it with you.