How to Read a Commercial Roof Replacement Bid

Two bids for the same commercial roof can differ by a factor of two, and the cheaper one is not necessarily the worse deal. Sometimes it is. Sometimes it is quoting a genuinely different scope that the document does not make obvious. Comparing them properly means knowing which line items actually move the number and which ones are there to look thorough.

Start with what is being installed over

Before anything else, find out whether each bid is quoting a tear off or a recover, because they are different projects.

A tear off strips everything down to the deck. A recover installs a new membrane over the existing system, usually with a cover board or new insulation between the two. Recover costs less, moves faster and sends far less to the landfill.

Recover is only available under two conditions: the existing insulation has to be dry, and the building cannot already be carrying two roof systems, because a third layer is not permitted and adds dead load the deck was never designed for.

So if one bid quotes a recover and another quotes a tear off on the same building, one of them is wrong about something factual. Either the insulation is wet and the recover bid has not checked, or it is dry and the tear off bid is selling work that is not needed. That is worth resolving before comparing prices, and core samples resolve it.

A bid that quotes either option without any evidence of core sampling is guessing. That is the single most useful thing to notice on a first read.

Insulation is where the money hides

New Jersey sits in climate zone 4A and the energy subcode sets a minimum continuous insulation value for the roof assembly. Older buildings are frequently below it, and a full replacement is the point at which that has to be corrected.

This is often the largest cost item an owner did not expect, and it is also the easiest one to leave out of a bid to make the total look competitive. If one proposal specifies insulation thickness and R-value and another says nothing about insulation at all, they are not comparable. The second one will find it later as a change order, or will install an assembly that does not meet code.

Look for the specific figures: what thickness of polyiso, what continuous R-value the finished assembly achieves, and whether tapered insulation is included where drainage needs correcting. Tapered costs more than flat and it is the correct answer where the roof ponds, so its absence on a roof that holds water is a red flag rather than a saving.

Membrane specification, not just membrane type

TPO is not a specification. The thickness matters, and so does the attachment.

TPO comes in 45, 60 and 80 mil, with 60 mil the usual commercial standard. A bid quoting 45 mil on a commercial roof is quoting a thinner, shorter lived membrane and should be priced accordingly. If the thickness is not stated, ask.

Attachment method matters as much. Mechanically attached, fully adhered and ballasted systems behave differently, cost differently and suit different buildings and wind exposures. A bid that says only the membrane brand has left out most of what determines performance.

The same applies to PVC, EPDM and modified bitumen. The material is the headline. The specification is the substance.

Wind uplift

The assembly should carry a documented FM approval or UL uplift classification matched to the design wind speed for the site, with the fastening pattern tightened at perimeters and corners where uplift pressure concentrates.

An exposed industrial parcel, a building near the coast and a sheltered downtown block have different requirements. A bid that specifies the same fastening pattern regardless of site is using a default rather than a calculation.

This item almost never appears on the cheaper bid, and it is a real cost difference. It is also the one that shows up during the first serious nor'easter.

Warranty tier

The word warranty on a proposal means very little on its own. What matters is the tier.

Material only coverage replaces defective material and nothing else, leaving you to pay the labour, which is most of the cost. Capped labour and material coverage pays for both up to a limit tied to the contract value. No dollar limit coverage pays repair labour and materials without that cap.

NDL generally requires installation by a manufacturer certified applicator and a manufacturer inspection at completion, both of which cost money and both of which are reasons a bid carrying NDL prices higher than one that does not.

Two bids that look close on price can be very far apart once the warranty tier is accounted for. That difference will stay invisible for years and then arrive all at once.

Ask for both terms separately: the manufacturer warranty length and tier, and the contractor's own workmanship warranty length. The second one is only as good as the contractor's survival.

Deck and contingency

Nobody knows the deck condition until the roof is off, so every honest tear off bid handles that uncertainty somehow.

The good approach is a stated unit rate for deck repair, for example a price per square foot of decking replaced, so that if problems are found the cost is already agreed. The bad approach is silence, which becomes a change order priced under pressure while your roof is open.

A bid with no deck contingency is not cheaper. It has moved the risk to you and not told you.

Permits, staging and access

Full commercial roof replacement in New Jersey always requires a construction permit filed with the municipal construction official. A bid that makes no mention of permitting either has not accounted for it or is not planning to file it. Both are problems.

Staging is the other item that separates a real plan from a price. Where will material be hoisted from, where does the dumpster go, how is tenant and loading dock access maintained, and how is the work sequenced so the building is never left with a large area of open deck. On a tight urban site these constraints can drive both cost and schedule more than roof area does.

Comparing like for like

The practical method is to put the bids side by side against the same list: tear off or recover and the evidence behind it, insulation thickness and R-value, membrane type and mil and attachment method, uplift rating and fastening pattern, warranty tier and both terms, deck repair unit rate, permit handling, and staging plan.

Once that table is filled in, most price gaps explain themselves. What is left after that is a genuine difference in labour rate or margin, and at that point you are comparing contractors rather than documents.

If a bid cannot be placed into that table because the information is not in it, the answer is not to guess. It is to ask, and to notice how readily the answers come.

Our commercial roof replacement page covers the tear off versus recover decision and the cost drivers in more detail, and a commercial roof inspection with core sampling is what settles which option your building actually qualifies for before you go out to bid. Newark owners can see local specifics on commercial roof replacement in Newark.

Related reading: what a no dollar limit roof warranty actually covers and commercial roof permit rules under the New Jersey Uniform Construction Code.