FAQS
Historic restoration can bring up many questions. This FAQ covers our process, services, and partnerships — and if you don’t find your answer here, we’re always happy to help.
1. Assessment & Documentation
Before any historic window restoration begins, WMG conducts a thorough assessment of the window’s current condition. This includes inspecting the frame, sashes, glazing, hardware, and surrounding trim. Documentation, including photographs and notes, is often taken to record the original state of the window, ensuring that restoration respects the historical integrity. WMG compares this assessment to project drawings and specifications.
2. Careful Removal of Sash for Offsite Restoration
WMG removes the historic sash from the opening. This step must be done with precision to avoid damaging delicate components like glass, moldings, or hardware. We then install temporary protection that matches your project’s specifications (plywood, plexiglass, and/or an insulated board up)
3. Deglazing & Cleaning
WMG utilizes a steam box to gently strip historic sash of paint and carefully remove damaged glazing putty. Original glass is catalogued and inspected for cracks, chips, or breaks. The glass is cleaned using gentle methods to remove dirt, grime, and old paint. If the glass is severely damaged, it is replaced with glass that matches the project’s specification (float glass, restoration glass, salvaged glass and/or mouth blown glass).
4. Sash Restoration & Repair
Over time, wood sash may become warped, rotten, or damaged. WMG addresses each sash individually. Any damaged sections are replaced or repaired using epoxy repair and/or dutchman repair methods. If the sash is too damaged to repair, we will discuss replication options with your team. The sash is then sanded and primed. The glass is reset and glazed by hand using a linseed oil-based putty. Each sash receives at least two final coats of paint.
5. Frame & Sill Repair
While WMG’s shop team is restoring sash offsite, our onsite team is addressing onsite frame and sill repairs. Frames are scraped to sound paint using vacuum scrapers to minimize dust and debris. Dutchman and epoxy repairs are made to areas of the frames and sills that have damage. If the frames or sill are no longer structurally sound, a full sill and/or frame replacement may be required. Repaired frames are then primed and finish painted.
6. Weatherproofing & Energy Efficiency
Based on the priorities and specifications of your project, WMG can provide a variety of discreet weather-stripping solutions. We also can offer custom exterior storm window solutions and installation.
7. Reinstallation & Final Adjustments
Once the restoration is complete, the sash is reinstalled into its original frame. If appropriate, restored hardware, pulleys, weights, and new chain or rope are also reinstalled. Our team makes any necessary adjustments to ensure it operates smoothly.
The duration of the project depends on how deteriorated the sash, frames, and sill are.
For restoration projects that involve the coordination of multiple trades, WMG recommends removing sash early on and re-installing them at the very end of the project in order to avoid damaging any original historic fabric
WMG’s millwork shop can replicate original cornice trim, including dentil mouldings, and custom casings for historic exterior restoration projects.
As a preservation contractor for historic buildings, WMG is licensed and bonded to perform work on public projects. We can provide insurance documentation, public works certificates, payroll documentation, and AIA invoicing for your public or private project.
WMG occasionally partners with general contractors and architects to complete window restoration projects for private homes that are listed on the national register of historic places. Contact us for a list of recommended partners.
WMG uses the Secretary of the Interior’s Standards for the Treatment of Historic Properties to guide our restoration approach. We also work with historic architects and building commissions to provide restoration solutions that address each project’s unique priorities.
WMG is located in the Philadelphia area. We have conducted window restoration for historic properties in New Jersey, Pennsylvania, Delaware, Maryland, and Virginia. Our team is happy to travel for the right project.
Yes! WMG has restored thousands of windows and have played a key role in national register building restoration. Check out our list of projects for detailed examples of projects.