Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Ameristar Home Additions & ADU: The Los Angeles Owner’s Guide
If you have an Ameristar home addition or ADU and a component is failing, the full replacement in Los Angeles typically runs $53,100 to $153,400 depending on square footage, foundation work, and finish level. We stock Ameristar-compatible parts and materials for additions and ADUs, and our crew installs them with a written price before any work starts. Most Los Angeles owners discover a problem the same way: a door stops latching because the framing settled, a window fogs between panes, or a corner of the addition pulls away from the main house enough to let water in.
Sawyer Remodeling is an independent contractor, not affiliated with Ameristar. That means we match the part to your specific addition or ADU without being tied to one supplier’s catalog. Luca Romano has been swinging tools in LA for over two decades, and the additions we see from Ameristar homes share common failure points: transition flashing at the roofline, door thresholds on the ADU entrance, and window seals on south-facing walls that get hammered by Los Angeles sun.
Which Ameristar Models This Applies To
Ameristar home additions and ADUs in Los Angeles fall into two broad categories: attached additions that tie into the existing roofline, and detached ADUs built on a separate slab or raised foundation. The compatibility gotcha most owners hit is that Ameristar additions built before roughly 2015 often use 2×4 exterior wall framing with R-13 insulation, while newer builds use 2×6 walls with R-19. That changes the window jamb depth, door frame width, and the type of trim that fits without looking hacked.
To identify the right part, check the permit packet or the original plans for the wall section detail. If you don’t have plans, measure the wall thickness at an exterior door: 4-1/2 inches total means 2×4 framing, 6-1/2 inches means 2×6. For windows, look at the spacer bar between glass panes; Ameristar used Intercept spacers on many Los Angeles installations, which fail as a fogged seal after 12 to 18 years in coastal air. We recommend OEM Ameristar parts when the addition is under a structural warranty, and quality aftermarket equivalents when it is not. The aftermarket manufacturers we use, including brands like Andersen and Milgard for windows and Therma-Tru for doors, typically match Ameristar specs at 20 to 30 percent below OEM list price.
Key Takeaways
- Full Ameristar addition or ADU replacement in Los Angeles: $53,100 to $153,400 installed.
- Know your wall framing depth before buying windows or doors; 2×4 and 2×6 builds take different parts.
- OEM makes sense under warranty; aftermarket saves real money once the warranty has expired.
- We stock common Ameristar-compatible window, door, and flashing parts on the truck for service calls.
Styles & brands we work with
Signs Your Ameristar Home Additions & ADU Is Failing
- Fogged or hazy windows. The spacer bar between panes has lost its seal, letting moisture in. On Ameristar additions in Los Angeles, south-facing windows fail first because the sun bakes the sealant. Once fogged, the glass unit needs replacement, not just the sash.
- Door that sticks or won’t latch. The addition’s framing has settled, or the threshold has shifted. This happens faster on Los Angeles hillside lots where soil moves with winter rain. A door that sticks at the top corner usually means the header has deflected slightly.
- Drywall cracks at the transition wall. Where the addition meets the main house, movement between the two structures shows as a diagonal crack. Ameristar used a standard butt joint at many transitions; the fix is a proper expansion joint or a flexible trim detail, not just patching the crack.
- Water staining at the roofline or ceiling corners. The transition flashing between the main roof and the addition roof is the number one leak point on Ameristar builds in Los Angeles. Rain drives in during winter storms and shows up as a brown stain months later.
- Floor that bounces or creaks in one spot. A section of the subfloor has delaminated or a joist has cracked. In ADUs with crawl spaces, Los Angeles moisture and poor ventilation accelerate this. If you feel movement near the water heater or laundry hookup, check the subfloor around that area first.
Replacement Cost & What’s Included
For Los Angeles homeowners, a full Ameristar addition or ADU replacement runs $53,100 to $153,400. The range is wide because it depends on whether we’re rebuilding structure, replacing the roof, swapping windows and doors, or all three. At the lower end, you’re looking at a smaller addition or ADU with finish-level materials and no major foundation work. At the upper end, you’re adding square footage, upgrading to energy-efficient windows, and addressing hillside foundation requirements.
| Scope of Work | Typical Los Angeles Price Range |
|---|---|
| Full addition replacement, 400-600 sq ft | $53,100 – $118,000 |
| Full ADU replacement, 600-800 sq ft | $106,200 – $153,400 |
| Window and door replacement only (addition) | $9,440 – $29,500 |
| Transition flashing and roofline repair | $4,130 – $12,980 |
| Subfloor repair or joist sistering | $2,360 – $7,670 |
Every quote we write includes the parts, labor, haul-away, and the 365-Day Done Right Promise: if it’s not done right, we make it right, backed in writing. The price you approve is the price you pay. No change orders, no surprise add-ons at the invoice. We also give you a written line-item breakdown so you can see exactly where the money goes.
See the difference
Before
After
Before
After
Before
AfterDIY or Call Us?
Some things you can safely check yourself: fogged window glass is obvious from inside, a sticking door can be tested by opening and closing it through the seasons, and water stains near the roofline are visible from the ground with a pair of binoculars. What you should not do is climb onto a second-story roof to inspect transition flashing, open up drywall to look for framing damage, or try to re-flash a roofline yourself. Falls from roofs are a leading cause of serious injury, and a bad flashing job leaks worse than the original problem. The structural connections between an addition and the main house carry real load; if you get that wrong, you’re looking at a much bigger repair than the one you started with.
If you’re unsure what’s failing, call us. We’ll send a background-checked, uniformed technician who will tell you honestly whether it’s a $500 flashing repair or a $50,000 structural replacement. The estimate is free.
FAQs
A properly built Ameristar addition or ADU in Los Angeles should last 50 to 70 years before major structural replacement, but the finish components have shorter lives: windows 15 to 25 years, doors 20 to 30 years, roof flashing 15 to 20 years, and deck or patio surfaces 15 to 25 years depending on sun exposure. Coastal Los Angeles air shortens metal flashing life by a few years compared to inland areas. Call (254) 272-5876 if you’re seeing early failure on any of these.
Some parts can, and some cannot. Fogged window glass cannot be repaired; the sealed unit must be swapped. A sticking door can often be re-shimmed and re-hung. Cracks at the transition wall can be patched, but they’ll return unless the underlying movement is addressed. We’ll always tell you the repair option first when it’s genuinely viable, and we won’t sell a replacement when a repair does the job. Call (254) 272-5876 for an honest assessment.
A window or door swap on an Ameristar addition usually takes a day. Transition flashing repair takes one to two days depending on access. A full addition or ADU replacement runs 8 to 16 weeks, and we’ll give you a written schedule before we start so you know what’s happening week by week. Call (254) 272-5876 and we’ll scope your specific job.
We stock common Ameristar-compatible parts on the truck: window glass units, door thresholds, flashing materials, and subfloor repair components. For OEM Ameristar parts that must come from the manufacturer, we’re typically looking at 5 to 10 business days for Los Angeles delivery. We’ll tell you which parts are in stock and which are special order before you commit. Call (254) 272-5876 and we’ll check availability while you’re on the phone.
Get a Written Price Before Any Work Starts
If your Ameristar home addition or ADU has a failing part, the fastest way to know what you’re dealing with is a free estimate from Sawyer Remodeling. We’ll send a background-checked technician to your Los Angeles property, assess the failure, and hand you a written, line-item price before a single tool is picked up. That’s The Relay Visibility Guarantee: you know who is coming, when they arrive, and what it costs. Good work doesn’t need a sales pitch, it just needs to be done right. Call (254) 272-5876 to schedule your free estimate.
Written by Luca Romano, Owner, Sawyer Remodeling at Sawyer Remodeling, serving Los Angeles and nearby areas.
