What Does Your ADU Window Warranty Actually Cover, and Who Pays When a Window Fails?

By Buz Artiano, BuildX | October 2026

Watch: Window Delays, Install Fails & What Builders Always Miss w/ Chad Nicoli | BuildX Podcast #25

You're thinking about putting a lot of money into an ADU, and you know that the windows you choose will affect the feel of your new ADU every single day. If one of them gets fogged up or won't close right in a few years, you have no idea who to call to get that fixed or who pays for it. Warranties for the window get talked about once in a meeting, and then the paperwork gets put into a folder that nobody ever opens again.

My name is Buz Artiano, founder of BuildX. We have built dozens of ADUs across Massachusetts, with most of our work on the South Shore and in Plymouth County, and every one of those ADUs has to pass a septic evaluation, stay within the lot coverage limits, and obey the state's by-right ADU rules before the windows are even installed. We handle all the design, permitting, and construction ourselves, so when a window fails in one of our ADUs, we get the call.

On the BuildX podcast we talked to Chad Nicoli, trade sales manager for Pella Windows and Doors in Eastern Massachusetts, about a window failure starting with the homeowner's first phone call to when the replacement was installed. We wanted the entire process on the record, because a warranty's only as good as the service behind it. So know that process before your windows are ordered.

What Does an ADU Window Warranty Actually Cover?

Coverage is divided up by component, and each component has its own time frame. Chad described the terms for the windows that his company sells: there is limited lifetime coverage on the frame as long as the original owner lives in the home, 20 years on the glass, and 10 years on all the moving parts, which means the hardware that opens, closes, and locks the window. Those time limits cover parts. Pella's published warranty guidance says that the labor on a covered product defect is included for the first two years from the date it was purchased, and every year after that will be dealt with differently.

Foggy glass is the problem most people see first. When moisture gets in between the panes of a window, that means that the seal has gone bad, and the glass manufacturer should be the one to deal with that. In the example we talked about, a window that fogs up within five years is definitely within a 20-year glass warranty, so the manufacturer will pay to replace the glass panel and the frame. But labor is only covered for 2 years, so the labor to install the new window can be the homeowner's responsibility even though the cost of the assembly is covered.

There are two more limits as well. Pella's advertised terms only give lifetime coverage to the person who originally bought the windows and as long as they are in an owner-occupied single-family home. The warranty coverage is shorter if the buyer no longer lives in the home or the window goes into a home that's not owner-occupied. If your ADU has a parent, adult child or tenant living there, you'll need to know how the manufacturer deals with warranty issues. So get the answer in writing for your specific situation. If a window gets broken by something hitting it, that will never be covered. Chad gave the example that a golf ball that breaks the glass is not a warranty claim.

The lifetime, 20-year, and 10-year examples were told to us in conversation and apply to one specific line of products, not every window this manufacturer sells. Pella has separate written warranties for its wood, fiberglass, and vinyl lines, other manufacturers determine their own terms, and so only the actual written warranty for your specific window line will tell you what's covered.

Who Do You Call When a Window in Your ADU Fails?

You would first call your builder. In the discussion we had on the podcast, the homeowner calls us, and we would then bring in the manufacturer's service rep. That rep goes out to your house first to see what's happening before anything is ordered or replaced.

If the rep says that the problem is with the product, a service request will be made and a manufacturer service tech comes out to inspect the window. Chad said that the service department is in-house, run by the window company itself. The order goes: builder, then service rep, then service tech, and the homeowner is the one who gets the fixed window when it's finished.

Who Pays: the Builder or the Manufacturer?

The outcome of the service visit will decide who pays. Chad was direct about the process. The rep gives the information to the builder, not the homeowner, and tells them what they found. Every service call ends one of three ways.

• A mistake during installation: the report tells the builder what was not installed correctly, and what needs to be fixed and then the builder is responsible for fixing it.
• A defect with the product: the report says the window itself was defective so the manufacturer covers the replacement part, but remember labor isn't covered if you're outside that coverage window.
• A non-warranty issue: Something hitting and breaking the glass isn't covered, and neither is a new window that feels a bit tight at first, but still closes and locks like it's supposed to.

The inspection decides who's at fault before any repair is ordered or scheduled. It doesn't promise the homeowner that they will get it fixed for free. With an installation error, the builder is responsible for the work. On a product defect, the part's covered, but if the labor period is over, the cost of the service visit and the installation can be the homeowners.

Some defects will happen no matter who the manufacturer is. A factory machine can run out of adjustment, a batch comes off the line too hot or too cold, or a trailer might get blown over on the road. What matters is that a builder and a manufacturer are still there to take care of it.

How Does a Failed Window Get Identified Years Later?

Every window has serial numbers etched into the glass, and the manufacturer has now started to add barcodes and QR codes to some of their products. The most useful information is the address. Chad told us that the service rep can look up the property, and if the windows were put in within the last 20 years, the manufacturer has all the order information on file.

From there the service representative gives all the information to the order entry department, the replacement sash is then ordered under warranty, and a service tech will come out and put it in. The manufacturer doesn't just ship a box to the builder and leave the switch to chance.

It's very difficult to read what is etched on a window that's five years old, trust us, we've had to do it. That's why being able to look up the address is important, and why we keep the window order together with the rest of the information on the property from day one. Make sure you keep the paperwork that tells you what kind of window you have and who manufactured it. It will make future service calls much easier.

Is a Stiff New Window a Warranty Problem?

Some resistance on a brand-new window is normal. Chad said tightness is the one issue people point out most with all windows, and installers are also sometimes surprised at how tight new windows are for a while. The manufacturer's instructions during construction are this: close the windows and lock them, don't let them sit open and keep the sawdust out of the tracks.

There is a definite difference between snug and wrong. A window that will open and close with a little effort and still locks completely is just breaking in. A window that won't close all the way, won't lock, binds hard partway needs adjustment or inspection, and manufacturer owner's manuals include things to check for exactly those operating problems. Tell your builder about those promptly, as soon as you notice them. Manufacturer labor coverage is only for covered product defects, so error in installation or just a routine adjustment isn't necessarily included, and a timely report gives the service rep the best chance to figure out the cause correctly.

We'd rather a new window start out a little tight, because it will loosen up with use. On our jobs we allow the windows to be closed and locked, and on some ADUs we put on a dry lubricant to help get the sash through its first cycle of opening and closing. When a unit still binds after that, we will deal with it as an adjustment to make or a problem to check out, and we bring in the service rep.

Is the Warranty Alone Enough to Protect Your ADU?

Builders like to tell homeowners that the warranty covers everything and that all failures are the factory's problem, but the info you just read said the opposite. When the rep finds that there's a problem with the installation, that report comes to us and it's up to us to fix it. A strong warranty doesn't do anything for a window that was put in wrong, so the warranty term is only half of it. The builder who did the installation is the other half.

Make sure you get these answers in writing before the windows on your ADU are ordered:

• What are the frame, glass, and moving-parts terms for this particular line of windows?
• Does lifetime coverage still apply when a parent or tenant lives in the ADU, and will it transfer to another owner later on?
• How long is labor covered for, and who pays for the service visit after that period is over?
• Who makes the first call to the manufacturer after the project is closed out?

Want to See How Our ADU Windows Are Specified and Installed?

You now know who inspects a failed window, who gets the report, and what's covered and what's not. The next step is seeing the windows in a finished ADU and asking the people who would build yours those four questions.