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ES Windows Home Additions & ADU: The West Covina Owner’s Guide
Adding square footage to a West Covina home with ES Windows products already in place runs $45,000 to $130,000 for a full addition, and $90,000 to $220,000 for a complete ADU. Mason Remodeling Co West Covina plans, permits, and builds these projects while matching new window and door openings to your existing ES Windows profiles so sightlines and hardware stay consistent. Most owners reach out after realizing their current setup won’t support the wall or roofline changes an addition requires, or after a builder told them their ES Windows units can’t be reused once a wall moves.
You should know what you’re getting before we ever pick up a tool. That means a written price, a named crew, and a plan for matching your existing windows before demolition starts.
Which ES Windows Models This Applies To
ES Windows manufactures aluminum-frame window and door systems built for the Southern California climate, and the product lines commonly found in West Covina homes from the 1990s through today include fixed picture windows, horizontal sliders, casements, and multi-panel sliding doors. If you’re adding a bedroom, building an ADU, or converting a garage, the key question is whether your existing units are standard-depth or high-performance thermal-break frames. The thermal-break versions measure roughly 2-1/4″ to 2-1/2″ in frame depth, while older standard aluminum runs closer to 1-1/2″. That difference matters when matching new jambs and trim to old openings.
Look for the manufacturer label etched on the glass corner or stamped inside the frame track. It will list the series and sometimes the fabrication date. If the label is gone, measure the visible frame depth from interior drywall to exterior stucco edge and take a photo of the corner joinery. We can identify most ES Windows series from that alone. For additions, matching the existing series is ideal but not always possible if the line was discontinued. In those cases, we spec a current ES Windows-compatible aluminum system with the same sightline width so the new openings don’t call attention to themselves against the old.
Aftermarket options exist for replacement glass and some hardware, but for structural changes, stay with OEM or an architecturally equivalent aluminum system. Cheap vinyl substitutes next to ES Windows aluminum frames look wrong from day one, and West Covina’s sun exposure fades and warps low-grade vinyl faster than most homeowners expect.
Styles & brands we work with
Signs Your ES Windows Home Additions & ADU Is Failing
- Gaps between glass and frame after a wall shift. West Covina sits on expansive clay soil in several pockets, and older slab foundations move with wet winters and dry summers. When a window frame torques, the sealed glass unit can start to separate, which shows up as a fog line or visible gap at the corner.
- Sliding doors that drag or jump the track. ES Windows sliding door rollers wear flat after 15 to 25 years, especially on doors facing afternoon sun near Cameron Park or the Eastland Center side of town. If the door suddenly rolls hard in one spot, the roller is done and the track may already be grooved.
- Water staining below the window corners. Aluminum frames with failed perimeter sealant let water run behind stucco. You’ll see discoloration on interior drywall near the bottom corners first, often months after a heavy rain.
- Condensation between the panes. Once the desiccant strip inside the sealed unit saturates, you get permanent fog. That’s not a cleaning issue. It means the inert gas fill is gone and the unit’s insulating value has dropped.
- Lock hardware that no longer aligns. As frames settle and shifts compound, the locking pawl and keeper drift apart. A window that closes but won’t lock is a real security problem, not a minor annoyance, and it often signals frame racking that a simple hardware swap won’t fix.
See the difference
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After
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AfterReplacement Cost & What’s Included
For a home addition in West Covina, expect $45,000 to $130,000 depending on square footage, foundation type, roof tie-in complexity, and whether you’re matching a second story or staying single level. ADU construction runs $90,000 to $220,000 and includes plan drawings, permits, site work, utility runs, framing, finishes, and window and door packages. Matching existing ES Windows units during either project typically adds $800 to $2,500 per opening depending on size and series.
Every Mason Remodeling Co West Covina project includes a written price before work starts. No verbal estimate that grows on the final invoice. The written scope lists every line item: demolition, rough framing, electrical, plumbing, drywall, stucco patch, window install, trim, paint, and debris hauling. If something changes mid-project, you get an updated written change order with a number on it before the work proceeds, not after.
Our labor carries a workmanship warranty, and the full project is covered by the 365-Day Done Right Promise: if anything is not right within a year of completion, we return and make it right at no cost to you.
DIY or Call Us?
Some things you can safely check yourself. Look for the model label on the glass corner and note the visible frame depth. Test each window’s lock engagement. Check for water staining at drywall corners. That’s useful information to have when you call, and it costs nothing.
What you should not do is pull a window or door frame out of a load-bearing wall on a West Covina addition without a structural plan. Window openings in exterior walls carry roof load through headers, and removing or enlarging one without proper shoring is how walls sag and stucco cracks spread. The same goes for garage conversions where the existing slab may not meet ADU habitable-space elevation requirements. That’s a code issue, not a preference.
If you’re anywhere in the planning stage, call (707) 760-7579. We’ll walk the property, look at your existing ES Windows units, and tell you what can be matched, what needs replacing, and what it will cost. In writing.
FAQs
In most cases yes, if the units are structurally sound and the new wall layout keeps their rough openings the same size and position. What typically kills reuse is frame damage from being pulled incorrectly, or the new design requiring different egress sizing for bedrooms. Call (707) 760-7579 and we’ll assess what can stay and what has to go.
A single-story addition usually takes four to six months from permit submittal to final inspection. A detached ADU can run six to ten months depending on utility trenching and plan check times at the City of West Covina. We keep the schedule honest and update you if plan check runs long.
Yes. Every addition and ADU we build in West Covina is permitted through the city, inspected at the required stages, and finalized with a certificate of occupancy where applicable. A project without permits is a liability you inherit when you sell, and we won’t build that way.
Only if you change the scope. Our written price covers what’s specified, and if you add or alter something mid-project, we hand you a written change order with a number before the work proceeds. Call (707) 760-7579 for a free estimate on your ES Windows addition or ADU project.
Written by Isaac Pruett, Owner, Mason Remodeling Co West Covina at Mason Remodeling Co West Covina, serving West Covina and nearby areas.
