Questions to Ask a Commercial Roofer
For the person choosing between bids on a commercial roof: an owner, a property manager, a facilities lead. Most such roofs are flat or low-slope, so the questions assume a membrane system and a building that stays occupied while the crew is overhead. They follow the decision in order: the contractor, the roof survey, the proposed system, the weeks of the work, the bid and contract, then warranty and upkeep.
Want questions from the whole vault instead? Try the random question generator.
The questions
Each question, and why to ask it
The contractor
How much of your work is commercial low-slope roofing, and how much is residential?
Why ask it
A company that mostly shingles houses runs different crews, equipment and suppliers from one that welds membrane on flat roofs every week. The useful form of the answer is a split by revenue over the last year, plus the kinds of roof they would turn down as outside their range.
How long has this office been roofing commercial buildings around here, and has the company ever gone by another name?
Why ask it
Longevity counts for more on a roof than on most hires: the warranty may run for twenty years, and the installer's share of it is worth nothing once the installer is gone. With a regional or national firm, the figure that matters is the age of the local branch and how many service technicians work out of it, since those are the people who would answer your leak call.
Are you licensed for commercial roofing here, and can I have the license number and the name it is held under?
Why ask it
Licensing differs by state and sometimes by city, and some places put commercial and residential roofing in separate classes, so ask how it works where the building stands and look the number up with the issuing body yourself. Check that the name on the license is the name that will appear on the contract.
Can your agent send certificates for general liability, workers' compensation and any umbrella policy, naming the building owner as additional insured?
Why ask it
Have the certificates come straight from the agent, and ask your own insurer or risk manager what limits they want to see on a job this size. If a lender or a tenant lease requires other parties to be named, hand that list over now so the paperwork is right before the crew arrives.
Which membrane manufacturers have approved you as an installer, and at what level?
Why ask it
Manufacturers generally issue their system warranties only on roofs laid by contractors they have approved, and several run tiers that decide which warranties a contractor can offer. One email to the manufacturer's local representative confirms the status.
How many roofs of this size and system have you finished in the last three years, and can I walk one?
Why ask it
A crew at home on a small retail roof can be stretched by a large warehouse, and the reverse holds for a tight roof crowded with equipment. The one to walk is at least three years old, so you see the seams and flashings after a few winters and not on handover day.
Who would be the project manager and the foreman, and how many jobs does each run at once?
Why ask it
You are hiring those two people as much as the company, and a foreman split across three roofs is on yours a third of the time. Meet the foreman before you sign, and see whether the contract can name both or at least require notice if either is replaced.
Which parts of the job, if any, go to subcontractors: the tear-off, the sheet metal, the installation itself?
Why ask it
Subbing out the tear-off or the sheet metal is ordinary on commercial work and tells you little by itself. The paperwork is what counts: each subcontractor's name and insurance certificates, and the manufacturer's word that the warranty stands whoever does the installing.
What is your safety record: your experience modification rate and any OSHA citations in recent years?
Why ask it
In the US, the experience modification rate is the figure workers' compensation insurers use to compare a company's injury claims with what is expected for its trade, and a roofer who bids commercial work will usually know theirs without looking it up. A very small firm may not be rated at all. What changed after their last recordable incident tells you more than the number does.
Can I call three owners or property managers you have worked for, including one who had to call you back about a leak?
Why ask it
The polished references will tell you the crew was tidy. The callback is the one worth your phone call: how many hours passed before someone was on the roof, whether the first repair held, and whether anyone argued about whose fault it was.
The roof survey
What did you find on the roof, and can I have the photos marked on a roof plan?
Why ask it
A bid that arrives with a marked-up plan and dated photos shows that somebody walked the whole roof instead of measuring it from satellite imagery. Keep the plan: it is the baseline for comparing the other bidders' findings, and for comparing this roof with itself in five years.
Is the roof that is on there now still under a warranty, and would your work affect it?
Why ask it
If a manufacturer's warranty is still running, repairs and even core cuts may have to go through that manufacturer or a contractor it has approved, or the coverage can end. Dig out the document and read its notice terms before anyone opens the membrane. A bidder who raises this unprompted is looking after your position as well as the sale.
Did you take core samples, how many, and what did each one show?
Why ask it
A core cut goes through every layer down to the deck, so it shows how many roofs are up there, what the insulation is and whether it is wet. Where each cut was made matters as much as how many there were: one in a dry corner proves little about the low spot by the drain, and each should be patched before the roofer leaves. A replacement price given without any rests on guesses about what is underneath.
How did you check for wet insulation: an infrared scan, a moisture meter, or the core cuts alone?
Why ask it
Trapped moisture decides whether a re-cover is possible and how much has to be torn out, so the method behind the number matters. What you want to leave with is a map of the wet areas in square feet, and confirmation that the bid is priced on that same quantity.
Is this roof a candidate for repair, a coating, a re-cover, or does it need full replacement?
Why ask it
Ask the bidder to make the case for the option one step cheaper than the one proposed and then say why they ruled it out. When three bidders recommend three different levels of work, the disagreement is usually about how wet the insulation is, which takes you back to the cores.
How many roof systems are on the building now, and does the local code allow another layer over them?
Why ask it
Building codes commonly cap the number of roof layers and bar covering wet or damaged material, but the wording and the enforcement vary, so have the bidder cite the rule that applies and confirm it with the building department. Weight is the other half: every added layer is load on the structure, and whether the frame can carry it is a question for a structural engineer, not the roofer.
What is the deck made of, and did you look at it from underneath?
Why ask it
Steel, concrete, wood, gypsum and lightweight concrete decks each take fasteners differently, and some stop holding them after decades of leaks. A look at the underside from inside the building, wherever it is exposed, catches rust and staining that nobody finds from above. If the new roof will be mechanically fastened, pull tests on the fasteners before the attachment is settled are a reasonable thing to request.
Where does water stand on this roof after rain, and what is causing it?
Why ask it
Ponding can come from clogged drains, too few drains, crushed insulation or a deck that has sagged, and each has a different fix at a different price. Invite the bidder back within a day or two of rain, or show your own photos, so the answer is not based on a dry roof.
How did you trace the active leaks back to where the water gets in?
Why ask it
On a low-slope roof water can travel along the deck or through the insulation before it drips, so the ceiling stain over the lobby is a clue and not a location. Listen for a method: a water test of one section at a time, a moisture scan, a seam probed by hand. Then get the second step in advance, meaning what they would test next, and at whose cost, if the leak comes back.
Could any of the existing roofing contain asbestos, and who tests for it?
Why ask it
Older built-up roofs, flashings and mastics sometimes do, and the rules on sampling, removal and disposal depend on where the building is. Three things to pin down before the price is final: who takes the samples, who pays the lab, and what a positive result does to the cost and the schedule.
If we did only the urgent repairs this year, how many more years would you expect from this roof?
Why ask it
This is the one to ask when the budget cannot cover replacement yet. Have the repair list priced separately, and ask what they would want to see at an inspection twelve months on, so the estimate of remaining life is something you can check.
The system
Which system are you proposing, by manufacturer, membrane type and thickness, and why that one for this building?
Why ask it
TPO, PVC, EPDM, modified bitumen and built-up roofs each have strengths, and the right pick depends on what the roof has to put up with: grease from kitchen exhaust, chemical discharge, heavy foot traffic, hail. A bidder who puts the same membrane on every building has not answered the second half of the question.
If this is a repair, what will you patch with, and is it compatible with the membrane that is there?
Why ask it
Membranes do not all bond to one another, and some single-ply sheets are damaged by asphalt-based cements, so a patch in the wrong material can fail or make the leak worse. The bidder should be able to name the existing membrane and the repair product by its maker. On a roof still under warranty, check that the method is one the manufacturer accepts.
How will the membrane be attached: mechanically fastened, fully adhered, ballasted or another way?
Why ask it
Attachment changes the price, the wind resistance and what the people below put up with: screws driven into a steel deck are heard in every office under it, while adhesive is quiet but brings odor and limits on the weather it can be applied in. The deck and the wind exposure of the site should drive the choice, and your property insurer may have a say, since some specify the assemblies they will accept.
What insulation and cover board are in the bid, and what R-value will the finished roof have?
Why ask it
Energy codes in many places require a replacement roof to meet current insulation levels, and the added thickness can affect flashing heights, door thresholds and the curbs under rooftop units. Find out what the requirement is where the building stands and whether the bid meets it, then walk the roof edge and the doors with the bidder to see what the extra height does at each.
How will the new roof drain, and are you adding tapered insulation, drains or overflow scuppers?
Why ask it
A new membrane laid on the old slopes ponds in the old places. The taper plan should show where the water goes, including where it goes if a primary drain clogs, and the bid should say whether plumbing work on the drain lines is in the price or left to someone else.
How will you flash the parapets, curbs, pipes and roof edge, and is new edge metal and coping included?
Why ask it
Leaks on a low-slope roof tend to start at the details and not in the open field of membrane. The manufacturer publishes a detail drawing for each condition, so the bidder can show you the ones that apply to your roof. Check whether any existing metal is being reused, since reused coping is one of the quieter ways a bid gets cheaper.
Will any rooftop units have to be lifted or disconnected, and who does that work?
Why ask it
Thicker insulation can leave unit curbs too short to flash to the height the manufacturer wants, which means extending curbs or lifting units with a crane. Gas lines, conduit, solar arrays and satellite mounts raise the same issue. Get in writing who disconnects and reconnects each one, whether that trade is in the price, and how long any unit will be off.
Does the proposed assembly meet the wind and fire ratings this building needs, and can I see the documentation?
Why ask it
The required ratings come from the building code where you are and sometimes from your insurer, so ask the bidder to name the tested assembly they are matching and send its listing. Forward that to your insurance contact before you sign, because a roof the insurer will not accept is an expensive thing to learn about afterward.
Where will walkway pads go, and how should other trades reach the equipment afterward?
Why ask it
Service technicians cross the roof more often than anyone, and dropped panels and screws do their damage along the same paths every time. Have pads laid from the hatch to each unit and around it, and ask what the roofer would want written into your HVAC service agreement.
How many years should this roof last on this building, and what would shorten that?
Why ask it
A warranty term is not a life expectancy, and a careful bidder gives a range with the conditions attached: foot traffic, ponding, grease or exhaust from the building, how often the drains get cleared. Write the figure beside each bid. It is the number to divide the price by when a thicker membrane or a longer warranty costs more.
During the work
How long will the job take, how big will the crew be, and in what order will you move across the roof?
Why ask it
The answer you can use is a phasing plan showing which section is open on which days. With it you can warn tenants, move stock or schedule around a production line, and it shows whether the roofer has thought about your building or simply divided the area by a daily rate.
How will you leave the roof watertight at the end of every shift?
Why ask it
The nightly tie-in between new roofing and old is where an unexpected storm gets in. A crew that opens only what it can close the same day, and has a named person check the tie-in before leaving, has a routine. Settle now who pays for damage inside if it fails anyway.
What will tenants and customers notice: noise, smells, dust, closed entrances or lost parking?
Why ask it
Tear-off and fastening are loud in the rooms directly below, and adhesives and hot asphalt carry odor. What you need from the roofer is which days will be worst over which part of the building, so tenants hear it from you before they hear it through the ceiling.
Can the loudest work be done outside business hours, and what does that add to the price?
Why ask it
Night or weekend work is possible on many jobs, though it may run into local noise rules and overtime rates. Get the premium as a separate line so you can buy it only for the sections over spaces that need it, such as a clinic, a call center or a restaurant at lunch.
How will you keep fumes out of the fresh-air intakes?
Why ask it
The choices include closing or filtering intakes near the work, switching to low-odor adhesives, or doing that section when the building is empty. Bring your HVAC contractor or building engineer into this one, because shutting an intake has consequences of its own indoors.
What will you do to protect what is under the roof: stock, equipment, ceilings and people?
Why ask it
On some decks, tear-off shakes dust and debris through to the space below, which matters most over food, medical supplies or open machinery. The plan should say whether interior protection is hung, who moves or covers stock, and whether anyone has to be kept out from under the working area.
Where will the crane, dumpsters and material deliveries go, and how will you protect the entrances and walkways below?
Why ask it
Walk the site together and mark it on a plan: which parking spaces close and for how long, where overhead protection goes above doors, and when lifts are scheduled. Pallets on the roof need the same care, because material stacked in one bay concentrates weight on the structure, so find out how the loads will be spread.
What does daily cleanup cover, on the roof and on the ground?
Why ask it
Insulation scraps and membrane offcuts blow off a roof in the first gust, and dropped screws end up in customers' tires. A magnetic sweep of the parking and loading areas at the end of each shift is a fair request. So is clearing the drains before the crew leaves, since debris in a drain turns the next rain into a pond.
What is your fall protection and safety plan for this roof specifically?
Why ask it
Hold out for a written plan for this site, not the company manual: how the edge is protected, how openings are covered and who is responsible on the roof each day. Skylights deserve a direct question of their own, since to someone walking backward with a roll of membrane an unguarded skylight is a hole.
Does any of the work involve torches, kettles or other open flame, and what are your hot work precautions?
Why ask it
Modified bitumen and built-up systems may be applied with heat, and a smoldering fire can show itself after the crew has gone home. Ask how long someone stays on fire watch after the last torch is off, where the extinguishers are kept, and whether your insurer or the fire marshal expects a hot work permit.
Who is my contact each day, and how will I hear about progress, problems and tomorrow's plan?
Why ask it
A short daily message with photos, the area finished and the next day's section is a reasonable thing to ask for on a commercial job. Decide who on your side receives it and who has the authority to approve a change on the spot.
If the roof leaks during the job, at night or on a weekend, who do we call and how fast will someone come?
Why ask it
Get a mobile number that is answered, not the office line, and a response time written into the contract. A crew that is ready for early rain can tell you exactly what is kept on the roof for an emergency seal.
Bid and contract
Can you break the price into a schedule of values: tear-off, insulation, membrane, sheet metal, drains, mechanical work, permit and disposal?
Why ask it
A schedule of values is the bid split into priced parts, and it does two jobs. It shows where two bidders differ, and it becomes the basis for progress payments, so each bill can be checked against work you can go up and see.
What unit prices apply if you find wet insulation or bad deck beyond what the bid assumes?
Why ask it
Have the assumed quantity and the price per square foot written in for each item: insulation replaced, deck replaced or repaired, wood blocking at the edges. Extra quantities should be photographed and signed off by you before the area is covered over, because nobody can measure them afterward.
What is excluded from this bid?
Why ask it
Read the exclusions before the inclusions. Mechanical and electrical disconnects, plumbing on the drain lines, lightning protection, asbestos handling, interior protection and engineering turn up there often, and each is a cost somebody will carry.
Who pulls the permit and arranges inspections, and is an engineer's letter or drawing needed?
Why ask it
Whether reroofing needs a permit, and whether a design professional has to be involved, depends on the jurisdiction and the size of the job. Ask what the bidder did on recent jobs in this municipality, then confirm it with the building department.
What is the payment schedule, is there retainage, and will each payment come with lien waivers?
Why ask it
Progress payments against the schedule of values, with a percentage held back until final completion, is a common commercial arrangement, though the lien rules behind it are set by state law. Have your attorney say which waiver forms apply where the building is and what to collect from suppliers as well as the roofer. A large sum due at signing, before any material is on site, is the term to question.
Can you provide payment and performance bonds, and what would they add to the price?
Why ask it
A performance bond puts a surety behind the roofer finishing the job, and a payment bond behind the subcontractors and suppliers being paid. Public projects commonly require both and some lenders do too; on a private job it is your call, so get the premium as a separate figure. Even if you never buy one, whether a surety will bond this roofer for a job your size tells you something about their finances.
How long is the price good for, and what happens if material costs or lead times move before you start?
Why ask it
Roofing materials can come with long lead times and prices that shift between bid and delivery. Look in the contract for an escalation clause. If paying early for stored materials locks the price, find out where they will sit and who insures them until they are on your roof.
How are change orders priced and approved, and who on each side can sign one?
Why ask it
The rule to get in writing is that no extra work starts without a signed change order showing the price and the added days, except to stop water coming in. Settle the markup on changes at the same time, so that it is not negotiated with the roof open.
When can you start, what finish date will you commit to, and what happens if you miss it?
Why ask it
Weather days are fair to exclude, so ask how they are counted and who decides. If a date matters to you, such as a tenant moving in or the start of the wet season, say so now and ask whether the contract can attach a consequence to it.
Warranty and upkeep
What manufacturer warranty comes with this roof: material only, or a system warranty that covers labor too, and for how many years?
Why ask it
The names sound alike and cover very different things: a material warranty generally replaces defective membrane, while a system warranty generally reaches the labor and the other components too. Read a sample of the exact document before you sign the roofing contract, and look for a dollar cap on what the manufacturer will spend.
Will the manufacturer's representative inspect the roof before the warranty is issued, and can I be there?
Why ask it
On system warranties the manufacturer typically sends an inspector, who lists defects for the roofer to correct. A copy of that list, with proof each item was closed out, belongs in your file. Tying the final payment to the issued warranty is a term worth asking for in the contract.
What do you warrant yourselves, separate from the manufacturer, and for how long?
Why ask it
In the first years the roofer is usually the one who comes when it leaks, whatever the manufacturer's paper says. The term belongs in the contract along with a response time for leak calls, and it is fair to ask what becomes of the promise if the company is sold or closes.
What do the warranties exclude: ponding water, hail, wind above a set speed, damage by other trades?
Why ask it
Go through the exclusions with your own roof in mind: the corner that holds water, the hail history of the area, the technicians who service the units. Where an exclusion matches something likely on your building, ask whether an upgraded warranty or a design change removes it.
What do we have to do to keep the warranty valid?
Why ask it
Many warranties expect periodic inspections, records of them, prompt reporting of leaks and repairs only by an authorized contractor. Get the list in writing and give it to whoever runs the building day to day, since a well-meant patch by a maintenance tech is an easy way to lose coverage.
Does the warranty transfer if the building is sold, and what does the transfer involve?
Why ask it
Transfers often require notice within a set time, a fee and sometimes an inspection. If a sale or a refinance is possible during the warranty term, get the procedure now and file it with the property records, because any deadline is likely to fall in the weeks around closing, when nobody is thinking about the roof.
Do you offer a maintenance plan, what does each visit include, and what does it cost per year?
Why ask it
A useful plan lists its tasks: clearing drains, checking seams and flashings, resealing pitch pans, a photo report with any repairs priced. Compare the yearly cost with what the bidder charges for a single leak call, and ask whether plan customers are answered faster.
What will you hand over at the end: warranty documents, an as-built roof plan, photos, product data and final lien waivers?
Why ask it
The closeout package is what the next property manager, a buyer or an insurer will ask for years from now. Make its delivery a condition of final payment, and ask for photos of what is now hidden, such as deck repairs and the layers under the membrane.
How to compare commercial roofing bids
Practical guidance for the conversation itself
Before you invite bidders
Pull the roof's paper trail
Find the old warranty, past leak reports, repair invoices and any earlier roof survey. Bidders who are handed the leak history price the roof you have, and the rest price a guess. The old warranty document also says who is allowed to touch the roof while it is still in force, which you need to know before the first core is cut.
Write one scope and give it to everyone
Bidders left to define the job will each define a different one. A single page stating the roof areas, the level of work you expect and the limits the building imposes gets you prices that describe the same thing. On a large or complicated roof, an independent roof consultant can write that scope and review the bids for a fee.
List what the building cannot tolerate
Hours when noise is impossible, rooms that cannot take dust, loading docks that cannot be blocked, tenants whose leases promise parking or quiet. Hand the list to bidders at the roof walk so their price already includes working around it.
Go up on the roof with each bidder
Go yourself or send whoever knows the building best. You see who cuts cores, who asks to look at the deck from below and who measures from the parking lot, and the bidder hears the leak history from someone who has lived with it.
Leveling the bids
Start with what each one found
Leveling means adjusting each bid until all of them describe the same job, and it begins with the surveys, not the prices: number of existing layers, wet area in square feet, deck type. Bids built on different findings cannot be ranked until one more core cut settles who is right.
Build one table of the assemblies
Give each bid a column and each of these a row: membrane type and thickness, attachment, insulation R-value, cover board, edge metal, warranty type. A low bid often turns out to carry a thinner sheet, reused coping or a material-only warranty.
Add the exclusions back in
Ask your mechanical contractor, plumber or electrician to price what each bidder left out, and add those figures to that bid. The order of the bids sometimes changes once all of them carry the same work.
Stress the unit prices
Multiply each bidder's unit price for wet insulation and deck replacement by twice the quantity the bid assumes. The result is what a bad day under the membrane costs with each company.
Running the job in an occupied building
Tell tenants before the dumpster arrives
Send the phasing plan, the working hours, one contact for complaints and the days that will be loudest over each space. Read the leases first for notice periods or restrictions on work, and ask your attorney or lease administrator which ones bind you.
Hold a kickoff meeting on site
Put the roofer's project manager and foreman, your building engineer, the HVAC contractor and security in one room a week ahead. Settle roof access, keys, intake shutdowns, staging and who may approve a change.
Ask to see the night seal
In the first week, have the foreman walk you along the tie-in at the end of a shift. You learn what a sound one looks like, and the crew learns that the owner looks.
Keep a leak log from day one
Record the date, the spot, the weather and a photo for every drip, starting before the crew mobilizes. The log separates leaks the building already had from ones that began during the work, which matters when someone has to pay for a ruined ceiling.
Bids to be wary of
A replacement price with no core cut
Without a core, nobody knows how many layers are up there or how much insulation is wet. The low number is then a starting point for change orders.
The same answer for every roof
A bidder who recommends full replacement without discussing repair or re-cover, or one membrane whatever the building does, is selling what they stock. Ask what would have to be true for a cheaper option to work, and see if the answer is specific.
A warranty described but never shown
Phrases such as 'twenty year warranty' mean little until you have read whose warranty it is, what it covers and what it excludes. A bidder who cannot produce a sample document before signing may not be approved to offer it.
A scope that fits on one line
A proposal that reads 'install new 60 mil TPO roof system' and a price leaves the insulation thickness, the attachment, the edge metal and the allowance for wet insulation for the roofer to decide later. What is not written down is not owed to you. Send it back for the detail before you compare it with anything.