Most building owners begin a stained glass restoration project the same way: they notice a problem — a cracked panel, bowed lead lines, failing putty — and they call a studio. The studio sends someone to look at the windows, prepares a proposal, and submits a number. The committee reviews the number, negotiates briefly on price, and eventually signs.
This process is intuitive, familiar, and deeply flawed. It places the person who profits most from the scope of work in control of defining that scope. It eliminates competitive pricing by creating a single-source relationship before specifications exist. And it removes any independent verification of whether the work, once done, actually meets the standard you paid for.
The correct process looks very different. Here is what it should look like — step by step.
Step 1: Independent Condition Assessment
Commission an independent inspection before contacting any studio
An independent condition assessment from a consultant who has no financial interest in the work produces an objective diagnosis of what is actually wrong with your windows — and, equally important, what is not wrong. The assessment document becomes the foundation for everything that follows: specifications, bidding, and monitoring.
A thorough condition assessment covers structural integrity of the lead matrix, condition of individual glass pieces, performance of the support system, evidence of active water infiltration, and documentation of historical significance. It should be accompanied by a complete photographic record of every window.
The assessment should explicitly categorize findings by urgency: what requires immediate attention, what can be deferred with monitoring, and what is cosmetically imperfect but structurally stable. This prioritization is essential for matching the scope of work to available budget.
Step 2: Written Technical Specifications
Translate the assessment into precise written specifications
Written specifications are the single most important document in a restoration project. They define what work will be performed, what materials will be used, what methods are acceptable, and what performance standards the finished work must meet. Without them, every studio is quoting a different project.
Good specifications address:
- Scope of work — which windows are included, what operations will be performed on each
- Material standards — specific lead profiles, glass types, solder composition, putty formulation
- Method requirements — whether windows must be removed to a studio or can be repaired in place, conservation requirements for historic glass
- Documentation requirements — photographs before removal, panel numbering and mapping, photos during and after
- Inspection milestones — at what stages the work will be reviewed before proceeding
- Payment schedule — tied to inspection approvals, not calendar dates
"Written specifications are the single most important document in a restoration project. Without them, every studio is quoting a different project — and you have no basis to hold anyone accountable for quality."
Step 3: Competitive Bidding
Solicit bids from multiple qualified studios on identical specifications
With specifications in hand, the market can set the price. Competitive bidding on a precisely defined scope eliminates the information asymmetry that makes single-source proposals so expensive. When three or four studios bid on the same work, the spread in prices reveals the true market value — and often exposes studios that are either dramatically over-pricing or under-scoping the work.
Studio selection should be based on:
- Demonstrated experience with comparable historic projects
- References from recent clients with similar project types
- Review of portfolio work — specifically work on historic, pre-1950 stained glass
- Understanding of and commitment to the specification requirements
- Financial stability and insurance coverage
- Price — but only after the above criteria are satisfied
Price is not the only criterion. A studio bidding 30% below the field may be planning to use inferior materials or inadequately trained labor. Specifications that include material and method requirements mitigate this risk, but studio qualifications must still be independently verified.
Step 4: Monitoring the Work in Progress
Review shop drawings and conduct interim inspections at defined milestones
Once work begins, independent oversight ensures specifications are being followed. For significant projects, this typically involves reviewing shop drawings before work begins, visiting the studio during releading or other major operations, and conducting an inspection before windows are reinstalled.
Problems caught during the work are far less expensive to correct than problems discovered after installation. If a studio is substituting materials, taking shortcuts in lead preparation, or mishandling fragile historic glass, independent inspection at the right milestones catches these issues before they are permanent.
Step 5: Final Acceptance and Payment Authorization
Conduct a final inspection before authorizing payment
Final payment should be contingent on a formal acceptance inspection confirming that specifications have been met. This is standard practice in construction projects and should be standard in stained glass restoration. An inspector reviews installed windows against the specification document, identifies any deficiencies, and specifies corrections required before payment is authorized.
The Correct Restoration Process — Summary
- Commission an independent condition assessment before contacting any studio
- Prioritize work by urgency to match scope to available budget
- Write technical specifications that define materials, methods, and performance standards
- Solicit competitive bids from multiple qualified studios on identical specifications
- Evaluate studios on qualifications and experience, not price alone
- Review shop drawings and conduct interim inspections at defined milestones
- Authorize final payment only after a formal acceptance inspection
Budget and Timeline Realities
For a building with multiple windows in varying condition, the total restoration scope can be large. A common and effective strategy is to phase the work — addressing the most critical windows in year one and deferring stable but worn windows to subsequent budget cycles. An independent assessment is essential for this strategy because it provides the priority ranking that determines the phasing plan.
Timeline expectations should account for studio scheduling (qualified studios for historic work are often booked 6–18 months out), lead time for specialty materials, the logistics of window removal and reinstallation, and weather windows for exterior work. Projects rushed to meet an arbitrary deadline almost always cost more and deliver lower quality.
The process described above — assessment, specifications, competitive bidding, oversight, acceptance — consistently delivers better outcomes at lower cost than the conventional "call a studio" approach. For churches and historic buildings that steward irreplaceable artistic heritage, there is no responsible alternative.
To discuss restoration consulting for your windows, contact Karl Erickson at (507) 312-9370.
