How to Read a Historic Window Restoration Bid
Why the Lowest Number May Not Be the Lowest Cost
Three historic window restoration bids arrive.
$780,000.
$925,000.
$1.1 million.
At first glance, the decision looks fairly straightforward. There is a $320,000 spread between the low and high bidder, and somebody is going to have to explain why the project should spend more than necessary. But before anyone circles the lowest number, there is a more important question:
Are all three contractors actually bidding the same work? In historic window restoration, the answer is often no.
One contractor may have included complete paint removal while another priced only removal of loose coatings. One may have included complete glazing restoration while another carried only visibly failed putty. One may have allowed for a reasonable amount of wood repair, while another excluded nearly everything discovered after paint removal.
The proposals may all say historic window restoration. The work behind those numbers can be substantially different.
For general contractors, architects, owners, and developers, properly leveling those bids before award can be one of the most important financial decisions made on the window package.
Start With Scope Before Price
Put the bid totals aside for a moment. Start with the scope. Take the restoration specification and create a bid-leveling matrix showing what each contractor actually included.
At minimum, compare:
sash removal and reinstallation
paint removal
wood or steel repairs
glazing removal and replacement
historic glass retention and replacement
hardware restoration
sash cords, chains, or balances
weatherstripping
priming and painting
frame and sill work
replication
access
temporary protection
lead-safe work
mockups
final adjustment and operation
You may discover that the $780,000 bid and the $1.1 million bid aren't really $320,000 apart.
They're pricing different scopes.
Until those differences are reconciled, comparing the totals doesn't tell you very much.
This is exactly why the specification matters so much before the project ever reaches bid day. We covered that side of the equation in How to Write a Better Historic Window Restoration Specification.
A better specification makes bid leveling much easier because contractors begin with more consistent assumptions.
Pay Particular Attention to the Word "Allowance"
Allowances aren't inherently bad. In historic restoration, they can be extremely useful because some conditions simply cannot be known until work begins. But an allowance can make a bid appear artificially low if you don't understand what sits behind it.
Suppose Contractor A includes $100,000 of anticipated wood repairs. Contractor B includes a $25,000 allowance. Contractor C excludes concealed wood deterioration entirely. Those numbers shouldn't be compared at face value.
Ask:
What condition is the allowance intended to cover?
What happens when it is exhausted?
How was the allowance established?
Does unused allowance return to the owner?
What level of routine repair is included before the allowance is touched?
The allowance itself isn't the problem. Ambiguity surrounding it is.
Read Every Exclusion
The exclusions page may be more important than the price page. A bid can become significantly less expensive by excluding difficult or uncertain work.
Look carefully for language such as:
Rot repair excluded.
Glass replacement by others.
Access by GC.
Hazardous-material abatement excluded.
Repairs beyond minor deterioration excluded.
Hardware replacement excluded.
Temporary enclosures by others.
None of those exclusions automatically makes the bid unacceptable. Some may be entirely appropriate depending on how the project is structured. But they have a cost. If the GC has to procure that work elsewhere, it needs to be considered before comparing proposals.
The correct comparison isn't simply:
Subcontractor A versus Subcontractor B.
It is:
Expected total project cost of Subcontractor A's scope versus expected total project cost of Subcontractor B's scope.
That is a much more useful comparison.
Find Out What "Restoration" Actually Means
This is where vague specifications become expensive. Ask each bidder to describe its restoration process.
For wood sash:
Does the process include complete coating removal? Is all existing glazing putty removed or only visibly failed material? Is the glass removed? Are the glazing rabbets cleaned and prepared? Are deteriorated joints repaired? Is the sash primed appropriately before glazing and finishing? Is the hardware restored? Are the windows returned to working operation?
A contractor pricing a lighter rehabilitation treatment can legitimately be much less expensive than one pricing comprehensive restoration. That doesn't necessarily make either contractor wrong. It means the project team needs to know which treatment it is buying.
The National Park Service's Preservation Brief 9: The Repair of Historic Wooden Windows is particularly useful here. Rather than treating every deteriorated window identically, it encourages evaluation of actual conditions and matching the repair approach to the severity of deterioration.
Don't Level Historic Windows by Quantity Alone
Another common trap is reducing the bids to a simple cost per window.
Bidder A: $5,000 per window
Bidder B: $4,300 per window
That can be a useful benchmark. It isn't necessarily a useful comparison.
Consider:
one-over-one
three-over-one
six-over-six
nine-over-nine
Those may all count as one window in the schedule. They don't represent the same restoration effort. Every individual lite introduces work: glass handling, glazing removal, rabbet preparation, bedding, securing the glass, tooling putty, painting, and working around additional muntin profiles. A true divided-lite 6-over-6 window contains considerably more detail than a one-over-one window of similar overall dimensions.
We explored this issue in detail in Why Lite Count Changes Historic Window Budgets because lite configuration is one of the most overlooked variables in restoration estimating.
Window count tells you the scale of a project. It doesn't necessarily tell you the workload.
Understand the Glass Assumption
Glass can create a significant scope difference, especially on large divided-lite projects.
Ask each bidder:
Is existing historic glass being retained?
What happens when glass breaks during restoration?
Who pays for glass already cracked before work begins?
What glass is specified for replacement?
Is safety glazing required in particular locations?
Is glass salvaged from nonrepairable sash?
Is specialty or reproduction glass included?
Imagine a project containing several thousand individual lites. A seemingly small difference in the assumed replacement percentage can become a meaningful difference in the contract amount.
Historic glass can also be an important character-defining component. The National Park Service's Guidelines for the Treatment of Historic Properties specifically address retaining and repairing historic window components and maintaining characteristics such as glazing configuration, sash, muntins, and profiles.
Glass shouldn't automatically be treated as a disposable commodity.
Look Carefully at Wood Repair
This is probably one of the largest sources of bid variation on historic wood-window projects. Ask what the bidder considers a normal repair.
Does the base restoration include:
minor consolidation?
small Dutchman repairs?
joint repairs?
localized deterioration?
Then ask where the base scope stops.
When does repair become:
a new rail?
a new stile?
a replacement muntin?
a replicated sash?
There should be a rational threshold.
If one contractor includes routine deterioration based on experience while another converts nearly every wood defect into additional work, the second proposal may look cheaper on bid day and behave very differently once production begins. That is one reason we recommend establishing repair thresholds and unit prices before award.
Check the Unit Prices
Unit prices deserve almost as much attention as the base bid. Suppose two bidders are only $40,000 apart.
Contractor A has reasonable unit pricing for rail and stile replacement. Contractor B is slightly cheaper initially but has substantially higher unit prices for the repairs most likely to occur. On a large project, Contractor B could ultimately become more expensive. Run a few scenarios.
What happens if:
10% of bottom rails require replacement?
5% of sash require replication?
15% more glass needs replacement than anticipated?
You aren't predicting that those conditions will occur. You're stress-testing the proposals. This can be one of the most revealing exercises during bid leveling.
It also connects directly to the approach discussed in Historic Window Restoration and Change Orders: How to Reduce Surprises: establish the commercial mechanism for likely unknowns before those unknowns become field emergencies.
Look at Access Assumptions
"Access by others" can represent a substantial amount of money.
Who provides:
scaffolding?
boom lifts?
swing stages?
interior lifts?
pedestrian protection?
sidewalk closures?
scaffold modifications?
And just as importantly:
For how long?
If the restoration contractor assumes the GC will provide a lift whenever needed, but the GC carried only limited equipment duration, there may already be a future cost issue hiding in the proposal. Access assumptions should be reconciled before award.
Understand Where the Work Happens
Is restoration performed:
entirely on site?
partially on site?
primarily in a dedicated restoration shop?
Each approach can work.
But they have different implications for:
site logistics
temporary protection
production capacity
environmental controls
occupied spaces
quality control
schedule
For occupied universities, hotels, schools, and government facilities, removing sash and performing intensive restoration in a controlled shop can be particularly valuable.
We discuss those logistics in Historic Window Restoration in Occupied Buildings.
If significant work leaves the site, ask another question:
How is everything tracked?
A 400-window project can involve hundreds of sash and thousands of individual pieces of hardware. The restoration contractor should be able to explain how those components are identified, stored, tracked, restored, and returned to their correct openings.
Evaluate Capacity, Not Just Craftsmanship
This is particularly important on large commercial projects. A contractor can be an exceptional craftsperson and still be the wrong fit for a 700-window project with an aggressive schedule.
Ask:
How many restoration craftspeople are available?
How many crews can operate concurrently?
What is the shop capacity?
What comparable projects have been completed?
How many major projects can the company support simultaneously?
Can resources be increased if the schedule changes?
What work is self-performed?
What work is subcontracted?
There is a real difference between knowing how to restore one window beautifully and having the infrastructure to restore hundreds of them predictably.
Both matter.
Look at the Schedule Behind the Price
Sometimes the least expensive proposal also contains the longest duration. That may be perfectly acceptable. But the GC needs to understand it.
If saving $100,000 on the restoration package extends scaffolding by two months, affects interior finishes, or delays enclosure milestones, the project may not actually save $100,000. Conversely, don't automatically assume the contractor promising the fastest schedule presents the lowest risk.
Ask how that schedule was developed. How many crews? What production rate? What assumptions were made about lite count? How are glazing and coating cure times handled? How are repairs incorporated into production? How does weather affect the sequence?
A credible schedule should have a credible production plan behind it.
Determine Whether Replication Is Actually Included
Historic restoration projects frequently contain windows or individual components that simply cannot be saved. That isn't unusual. The question is whether the bidder planned for it.
Can the contractor replicate:
sash?
complete frames?
muntin profiles?
rails and stiles?
steel components?
doors?
If replication is subcontracted, understand to whom. If it is excluded, determine who owns that scope.
For projects using federal historic tax credits, the National Park Service provides specific guidance on Evaluating Historic Windows for Repair or Replacement and emphasizes documenting conditions before replacement is proposed. That decision is much easier to manage before demolition than afterward.
Review the Mockup Requirement
If the project requires a mockup, make sure everyone priced the same thing.
Does the mockup include:
complete restoration?
glazing?
repairs?
paint?
hardware?
weatherstripping?
installation?
architect review?
revisions after review?
And perhaps most importantly:
What happens if the approved mockup establishes a treatment different from what the contractor originally assumed?
Resolve that question before production.
For a deeper explanation of why this matters, see Historic Window Mockups: Why They Matter.
Ask What Is Actually Warranted
Warranty language can reveal quite a bit about the bidder's understanding of the work.
Review:
workmanship warranty
coating warranty
glazing warranty
replicated components
hardware
exclusions
Historic restoration isn't a factory-produced system, so warranties will naturally differ from manufactured replacement-window packages. That's understandable. But there should still be clear accountability for the work performed.
Consider Preservation Experience
The restoration subcontractor does not replace the architect or preservation consultant. But the contractor should understand the environment in which the project operates.
That includes familiarity with:
the Secretary of the Interior's Standards
historic tax credit expectations when applicable
repair-before-replacement principles
preservation mockups
historic materials
documentation requirements
The National Park Service's Preservation Briefs provide technical guidance specifically intended to help owners and professionals preserve, rehabilitate, and restore historic buildings. That knowledge matters when field conditions require decisions.
You want the restoration subcontractor identifying potential preservation concerns before work proceeds—not after the architect or preservation consultant discovers the problem.
Compare Risk, Not Just Price
Once you've normalized the scope, take one more step. Evaluate the risk carried by each proposal.
Scope Risk
How much remains undefined?
Change-Order Risk
How aggressively are repairs excluded?
Schedule Risk
Does the contractor have sufficient production capacity?
Technical Risk
Does the company actually specialize in this work?
Preservation Risk
Does the team understand historic materials and review requirements?
Execution Risk
Has the contractor successfully delivered projects of comparable size and complexity?
This does not mean selecting the most expensive contractor. It means understanding what you're buying.
Build a Simple Bid-Leveling Matrix
Before award, create a table with bidders across the top and these categories down the side:
Base Bid
Defined Restoration Scope
Paint Removal
Glazing
Glass
Wood/Steel Repair Allowance
Unit Prices
Hardware
Weatherstripping
Replication
Access
Temporary Protection
Lead-Safe Work
Mockup
Schedule
Crew Capacity
Warranty
Major Exclusions
Clarifications Required
Then normalize the proposals for known scope differences.
Only after that should you return to the total. You may still select the lowest bidder. Sometimes the lowest bidder really is the best value.
But now you know why.
Final Thoughts
Historic restoration bids aren't difficult to compare because contractors are deliberately making them complicated. They're difficult to compare because historic buildings are complicated.
There are unknown conditions. There are different treatment levels. There may be hundreds or thousands of individual components. And there are legitimate differences in how restoration contractors approach the work.
The solution isn't to ignore those differences and simply award the lowest number. It's to expose the differences before award.
A properly leveled bid should tell the project team:
What is included?
What is excluded?
What remains unknown?
How will the unknowns be priced?
Can this contractor actually execute the work within the project's schedule?
Those questions matter more than the number at the bottom of the proposal. Because the least expensive historic window restoration bid on bid day isn't necessarily the least expensive window package when the building is finished.
The goal is not the lowest bid.
It is the best-defined scope, appropriate expertise, manageable risk, and lowest responsible total project cost.
That's a much better definition of value.
