How Insulation Subs Bid and Bill Commercial Work

On a commercial job the word "insulation" covers work in at least three specification sections, and they are often bought from different subs. The National Insulation Association describes its members as contractors, distributors, fabricators and manufacturers that provide thermal insulation "to the commercial, mechanical, and industrial markets" (NIA), which is a reminder that a mechanical insulator and a building insulator are often different companies. Before you price, read the bid package to see which of these the GC has put in your trade.

The drywall side of this line (blocking, head-of-wall and who installs sound batts) is covered in how drywall and framing subs bid, and the mechanical side in how HVAC subs bid and bill. The rest of this guide is the insulation contractor's own view.

A single dollars-per-square-foot number hides the scopes that cost the most. Take off each one the way it is installed and priced:

Two spec habits change the firestopping number. The federal guide specification asks for firestopping materials "supplied from a single domestic manufacturer", and where no tested system exists for a condition, a "manufacturer's engineering judgment" submitted for approval before installation (UFGS 07 84 00). Price the system the spec allows, and list in your qualifications any conditions you expect to need an engineering judgment.

Insulation is buried inside walls and ceilings, so most of the paperwork happens before it is covered. Plan your submittals early; the method is in how to prepare a submittal.

• Building insulation: product data for the blankets, vapor retarder, tape and accessories, indoor-air-quality certificates and the manufacturer's instructions. The guide spec also wants materials delivered "in original sealed wrapping bearing manufacturer's name and brand designation, specification number, type, grade, R-value, and class" (UFGS 07 21 16).
• Firestopping: shop drawings of each firestopping system, product data, installer and inspector qualifications, and inspection reports. Where more than five penetrations or joints get firestopping, the drawings show each location with its "F" "T" and "L" ratings (UFGS 07 84 00).
• Mechanical insulation: a booklet of MICA plates (installation details from the Midwest Insulation Contractors Association's National Commercial & Industrial Insulation Standards), product data for pipe, duct and equipment systems, samples, and display samples: "actual sections of installed systems" kept on site during construction (UFGS 23 07 00).

The inspections set the order of work. The firestopping guide spec says "do not cover or enclose" firestopped areas "until inspection is complete and approved", and where an inspector is required, that inspector "must be completely independent of" the installer, manufacturer and supplier. It also says to apply firestopping at pipe and duct penetrations "prior to insulating, unless insulation meets requirements specified for firestopping" (UFGS 07 84 00). The mechanical spec says not to apply insulation until the specified tests are completed (UFGS 23 07 00). If the drywall crew is waiting on you, an inspection that has not been called is your delay, so ask the GC to put firestop inspections on the schedule by floor.

Split the schedule of values so each scope on each floor is its own line, and give the inspection paperwork its own line too. A fictional $172,400 subcontract for building insulation and firestopping on a two-story building, with pipe insulation excluded:

Line 8 matters more than it looks. Inspectors find penetrations other trades added after you finished a floor; if correcting them is priced as base work, say so, and if it is extra work, write it up as a change order request with the penetrations listed by location.

The fictional "Pinecrest Insulation" holds the $172,400 subcontract above with 10% retainage. In period 3, the level 1 exterior batts go from 40% to 100%, sound batts start at 25%, level 1 firestopping goes from 30% to 55%, and the batts for level 2 are delivered and stored dry on site.

Checks: $8,640 + $12,960 = $21,600; 25% of $27,800 = $6,950; $9,360 + $7,800 = $17,160 = 55% of $31,200. Previous billing on these lines was $8,640 + $9,360 = $18,000, and $18,000 + $34,910 = $52,910 to date, which equals $21,600 + $7,200 + $6,950 + $17,160.

Batts stored dry on site are billable as stored material only where the subcontract allows it, and the guide spec says not to let insulation become "wet, soiled, crushed", so photograph the batts in storage. How stored material and retainage work on the form is covered in how to fill out a pay application as a subcontractor and how to calculate retainage.

Insulation is finished early in the building and then hidden, but retainage on it is usually held to the end of the job like everyone else's. The firestopping records are what get it released: the guide spec asks for a written report of "locations of and types of penetrations and types of firestopping used at each location; record type by UL listed printed numbers", and an inspection report that the work was applied to the manufacturer's recommendations (UFGS 07 84 00). Build that location log as you go, floor by floor, not at the end.

• Firestop location report with the tested system number at each penetration and joint.
• Inspection reports for firestopping, and any corrections signed off.
• Product data and certificates for every insulation product used.
• Your warranty, on the terms the spec sets; read the warranty article before you bid, as terms vary by project.
• Final lien waiver and the request for retainage.

Where your work sits among the other trades from bid to closeout is in the subcontractor's guide, and the whole job's phases in the construction project lifecycle.

When a GC invites you to an insulation package through Trade bids in Conflo, you read the scope and the GC's scope items, ask questions (every bidder sees the answer, not who asked), acknowledge each addendum, and submit a base bid with each scope item marked included or excluded and an optional amount to break it out. That is where "firestopping of other trades' penetrations" or "pipe insulation" gets a clear yes or no. There is no unit-price field, so put your per-penetration and per-square-foot prices in your qualifications or your attached proposal.

Under contract, you bill in Pay apps: percent complete this period and materials stored on each line, with previous billing carried forward, no line billed past 100%, and retainage worked out on work and stored material to date. You can attach backup to the pay app, such as a delivery ticket or a firestop inspection report, but not to a single line, and the GC approves or sends back only the lines that are wrong, each with a note.

An insulation bid is won by saying exactly which of the three scopes you carry, and paid by keeping firestopping inspections and records moving floor by floor.

Before your next bid, add the scope table above to your proposal and mark each row included or excluded.

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1. UFGS 07 21 16, Mineral Fiber Blanket Insulation (August 2023, change 1) — Whole Building Design Guide (USACE, NAVFAC, AFCEC). Read October 22, 2026.
2. UFGS 07 84 00, Firestopping (May 2010, change 1) — Whole Building Design Guide (USACE, NAVFAC, AFCEC). Read October 22, 2026.
3. UFGS 23 07 00, Thermal Insulation for Mechanical Systems (August 2024) — Whole Building Design Guide (USACE, NAVFAC, AFCEC). Read October 22, 2026.
4. About NIA — National Insulation Association. Read October 22, 2026.