Hey everyone,

I’ve been running into ongoing challenges with HVAC cost estimation specifically on remodel projects, and I’d really appreciate insights from anyone who’s been doing this longer than I have.

New construction is usually straightforward for me—clear plans, predictable duct paths, and mechanical systems that make sense. But remodels? Completely different beast.

These are the main issues I keep hitting:

• Existing ductwork that looks fine during the walkthrough but turns into a surprise once ceilings come down

• Labor hours climbing because access is tighter than expected

• Older buildings triggering unexpected code-related upgrades

• Equipment needing to be replaced mid-project when the existing system can’t handle the revised load

• Subcontractor quotes coming back with huge variation

• Clients pushing back when change orders keep stacking up

I usually add a buffer, but sometimes even that doesn't save the margin. A couple of projects have ended up being a lot thinner than they should’ve been.

For anyone experienced with HVAC remodel estimating:

How do you get your numbers right on remodels?

• Do you depend heavily on detailed site inspections?

• What contingency percentage works for you?

• Any solid tools or workflows for documenting existing conditions?

• How do you set realistic expectations with clients early on?

I’m genuinely looking to tighten my approach. At ALM Estimating, we handle complex takeoffs all the time, but remodel HVAC jobs still throw curveballs—and I want to keep improving how we break them down.

Any advice, lessons learned, or even mistakes worth avoiding would be a huge help. I’d rather fix my process now instead of underbidding another remodel without realizing it.

Thanks in advance to anyone who shares their experience.