Andersen Home Additions & ADU Nationwide | Barrett & Sons Construction

Andersen Home Additions & ADU: The Los Angeles Owner’s Guide

If you’re planning a home addition or ADU in Los Angeles and want Andersen windows and doors worked into the build, we install them daily. A full home addition with Andersen products typically runs $53,100-$153,400 in Los Angeles, and an ADU with Andersen windows and doors runs $106,200-$259,600. Most owners reach out after an existing Andersen window or patio door in their add-on space fails, or when they’re starting fresh and want the same Andersen line they already trust on the main house.

We’re an independent construction company, not affiliated with Andersen, but we’ve been installing their windows, doors, and trim packages across Los Angeles since 1998. Tom Barrett grew up in the San Fernando Valley, not far from the old stretch of Van Nuys Boulevard where his dad used to take him to watch crews pour foundations on weekends. He learned the trade at Los Angeles Trade-Technical College, and he’s been at this long enough to know which Andersen parts hold up in our climate and which ones don’t.

Key Takeaways:

• Andersen window and door packages for additions and ADUs typically add $8,000-$25,000 to the project, depending on the series and unit count.
• We install Andersen 100 Series, 200 Series, 400 Series, and A-Series on additions and ADUs throughout Los Angeles.
• Written change orders before any scope change. Permits pulled on every eligible job. 90-Day Done Right Promise on the finished work.

Which Andersen Models This Applies To

We work with four Andersen series on home additions and ADUs in Los Angeles. The 100 Series is the fiberglass-and-Fibrex value line, most common on ADU rentals where budget matters and the windows stay closed half the year. The 200 Series is wood-core with vinyl cladding, a solid mid-range pick that handles Los Angeles sun exposure better than raw wood. The 400 Series is the workhorse for primary home additions: all-wood interiors, Perma-Shield exterior cladding, and the series most homeowners ask for by name. The A-Series is their architectural line with the widest color and hardware selection, and it’s what we recommend when an addition wraps the corner of the house and has to match existing Andersen units exactly.

Here’s the compatibility gotcha most owners don’t know: Andersen glazing units and sashes are not interchangeable between series. A 400 Series sash will not fit a 100 Series frame, even if the rough opening is the same. If you’re adding onto a Los Angeles home that already has Andersen 400 Series windows, we spec 400 Series for the addition so the sightlines and hardware match. Mixing series on the same elevation looks off, and it hurts resale.

On the OEM versus aftermarket question: for Andersen, we use OEM almost exclusively. Their glazing units carry a 20-year glass warranty, and aftermarket insulated units for Andersen frames rarely match the spacer bar or low-E coating. If you’re replacing a failed insulated glass unit in an existing Andersen window that’s staying in the wall, OEM is the only way we’ll go. The one place we’ll consider a quality aftermarket part is hardware: hinge sets and operator mechanisms from a reputable supplier can be fine if Andersen has discontinued the line.

Signs Your Andersen Home Additions & ADU Is Failing

• Condensation between the glass panes. This is the classic sign of a failed seal in the insulated glass unit. Once the desiccant inside the spacer bar is saturated, the unit fogs from the inside and no wiping fixes it. We see this most often on Los Angeles ADUs that face west and bake in afternoon sun. The fix is a new glazing unit, not a new window.
• The sash sticks or won’t stay open. Balances wear out, especially on double-hung units that get exercised daily. If the sash drops when you release it, the balance system has failed. On Andersen 400 Series, that’s a replaceable cartridge, and we stock the common sizes on the truck.
• You can feel air moving around the weatherstrip. Over five to seven years in Los Angeles heat, Andersen compression weatherstrip loses its spring. That’s an easy fix and cheaper than a whole unit, but if the frame has racked because the addition settled, you may need a full replacement.
• The patio door drags or jumps the track. Andersen gliding doors have a roller assembly that wears flat from daily use and hard water. If the door shudders or the handle binds, the rollers are done. This one’s worth fixing early because a dragging door chews up the track, and then the track is a much bigger job.
• Drywall cracks spreading from the window corners. This one’s not always the window. In Los Angeles additions, it often means the header wasn’t sized right or the opening frame wasn’t tied into the wall properly. We’d pull the trim and inspect before ordering anything.

Replacement Cost & What’s Included

For a Los Angeles home addition or ADU project with Andersen products, here’s the cost breakdown we give up front:

What drives the range on a Los Angeles addition is the same thing that drives every quote we write: site access, foundation condition, and how much of the existing structure has to move. We don’t pad the number to make the job look important. The quote you get is the price we build to, and every change after that arrives as a written change order before a single nail moves. The 90-Day Done Right Promise covers the finished work, and Andersen’s factory warranty covers the windows and doors themselves.

DIY or Call Us?

Some things you can check yourself. If a window fogs, check whether the condensation is between the panes or just on the room-side glass. If it’s room-side, that’s humidity, not a failed unit. Run a finger along the weatherstrip. Pull the hardware and look for part numbers stamped on the sash. Knowing what you have before you call saves everyone time.

What you shouldn’t do is attempt a full window or door replacement on an addition or ADU without a general contractor license, and here’s why. In Los Angeles, exterior window and door work on living space triggers local building code requirements for egress, and an ADU has its own set of California Title 24 energy rules. If you cut a rough opening in the wrong spot or miss an egress requirement, the permit inspector catches it, and now you’re paying us to undo what you already paid for. The inspector works for you, not for me, and that’s exactly why I like him. Call (877) 610-1318 and we’ll walk you through what you have and what it’ll take.

FAQs

How long do Andersen windows and doors last on a Los Angeles home addition?

Andersen 400 Series and A-Series windows with OEM glazing units typically last 20 to 30 years in Los Angeles before needing significant work. The fiberglass and vinyl-clad frames hold up well to sun exposure, but hardware, balances, and weatherstrip usually need attention around the 6- to 10-year mark. Call (877) 610-1318 if a unit on your addition is failing early, and we’ll tell you whether it’s a warranty claim or a repair.

Can you repair a failed Andersen window instead of replacing it?

Yes, and we do it all the time. A fogged insulated glass unit can be replaced without pulling the entire window frame, as long as the sash and frame are square. Failed balances, worn weatherstrip, and most hardware issues are repairable too. If the frame itself has rot or racking, replacement is usually the honest call. We’ll give you a straight answer before any money changes hands.

How long does an Andersen window or door replacement take on an addition?

A single window replacement in an existing opening takes one to three hours. A patio door swap usually takes half a day. A full addition with Andersen windows and doors runs two to five months depending on scope, and an ADU from ground-break to final inspection typically runs five to nine months in Los Angeles. We’ll put the timeline in writing when we quote the job.

Do you stock Andersen parts, or do I have to order them?

We stock common Andersen balance cartridges, weatherstrip sets, roller assemblies, and hardware on the truck, so most repairs on Los Angeles additions happen same-day. If you need a custom-size glazing unit, that’s ordered from Andersen and usually arrives within one to two weeks. Call (877) 610-1318 and we’ll tell you whether your part is on the truck or on order before you schedule anything.

Call Barrett & Sons Construction

If you’re planning a home addition or ADU in Los Angeles and want Andersen windows and doors installed by a company that’s been doing this since 1998, call (877) 610-1318. We’ll talk through your project, give you a written quote with real numbers, and pull permits on every eligible job. We’ll do it right the first time, or we’ll come back and make it right.

Written by Tom Barrett, Owner, Barrett & Sons Construction at Barrett & Sons Construction, serving Los Angeles and nearby areas.