Questions covered in this guide
Put both projects on one opening list
If siding and windows are being replaced together, give both contractors the same list of openings and intended products. Record the planned work dates, what cladding will be removed and which trim will remain. Ask whether either proposal assumes the other contractor has already prepared or protected the opening.
Confirm the selected window approach
Pella describes new-construction windows with perimeter nail fins. Its guidance allows their use in replacements when cladding is opened. Have the window installer identify the actual installation reference for your project and explain how it connects to the siding plan. The term new construction describes a product or installation approach here; it does not mean every replacement project should use it. Ask for the reason the chosen detail fits the exposed wall conditions.
Assign the interfaces explicitly
Make a responsibility matrix for opening preparation, water-management layers, window setting, exterior trim, siding returns, sealing and temporary weather protection. Ask who checks each interface before it is concealed and what photos or records will be retained. Record how work pauses will be handled if one trade is delayed. For hidden damage, agree on who documents it, who prices it and who obtains approval. Compare the two contracts together to find missing or double-counted work.
Build a combined budget without overlap
Ask each contractor to mark inclusions and exclusions against the shared matrix. Carry only the amounts that are not already in the other proposal, and keep unresolved work separate. Save the final sequence with the product order. The window calculator helps with a supported replacement allowance, but it does not price a siding project or decide how the two exterior systems should be connected.
Sources and supported claims
Pella describes new-construction windows with perimeter nail fins.
Source ↗ · national · Checked 2026-10-12
Its guidance allows their use in replacements when cladding is opened.
Source ↗ · national · Checked 2026-10-12
More help with this decision
- Window replacement cost calculator
- Insert vs. full-frame window replacement: compare the scope
- Window U-factor vs. SHGC: compare the labels in your replacement quotes
- Compare contractor quotes: price, scope and missing work
- A homeowner handoff checklist for new windows
- Aluminum-looking windows: ask what each frame surface is made of