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Good window installation?

nj_homeowner | Posted in General Questions on
We are building a new house in NJ, and have installed about 50 Andersen 400 Series Woodwright double-hung windows.
The windows look beautiful, but after reading the installation instructions, I am very concerned about how they were installed.
The instructions call for caulking overlaps on the nailing flange, caulking around the outside of the entire rough opening before inserting the window, then lapped flashing tape covering the whole flange, then more caulk all the way around the whole window.
When our windows were installed, they used no caulk and no proper flashing tape.  Instead they simply nailed the non-caulked windows, then taped the flange with Tyvek housewrap tape.
For the pan flashing, they used a formable tape, but only on the outer half of the rough sill, and only about an inch up the sides.
They installed shims on the bottom of the windows only, none on the sides.  They insist side shims are not necessary, and claim they in fact can cause problems in the future.
My builder says the windows are fine.  They have installed thousands of them like this, he says, and never had a problem.  He very much wants me to drop the subject.
I have read articles and watched videos, none of which say this method is adequate.  I have also asked certified window installers, who say “no way.”  One certified Andersen installer told me he is positive the windows will leak.  Others tell me I should have the builder redo all of them, even though most of them have been fully trimmed outside, and most of the siding is done.
Can anyone knowledgeable please opine about this?  Are my windows ok?  Is caulking and flashing tape really needed?  Should I insist that my builder redo them, which he will almost definitely refuse to do?  Is there a way to fix them without removing them (or the ext trim and siding)?  If I leave them as-is, what is likely to happen?
Thank you very much,
* EDIT *

Added photos showing one of our windows as installed, and the pages from the Andersen instructions showing steps that were omitted.

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  1. Peter Yost | | #1

    It is hard to evaluate your window installations without images at key sequences in the installation.

    It sure does not SOUND as if the installation was robust. Bear in mind that there are two major categories of installation: face-sealed and water-managed. These are detailed in the GBA Detail Library and also key to the information in the BSC Water Management Guide (


    1. nj_homeowner | | #18

      Ok! Photos added. We have no caulk or proper flashing, housewrap goes behind top flange, not lapped over. Is this ok?

  2. Expert Member
    RICHARD EVANS | | #2


    Did your plans have window flashing details? If so, and the builder didn't follow the plan details then I would ask them to re-do them. If you left the flashing plan up to the builder then I would keep what you have.

    As long as the sill had some kind of durable seal (flex tape) then you are probably fine. Especially if the sill is sloped and you have a vented rain screen.

    1. Expert Member
      MALCOLM TAYLOR | | #3

      With or without flashing details on the plans, the default is the manufacturer's installation instructions. if they didn't follow them they are also not following the building code. The "we always do it this way" excuse is a waste of the builder's breath.

      1. nj_homeowner | | #5

        I agree with you. The default should absolutely be to follow the mfr instructions. Is it true that not following the instructions is a code violation?

        1. Bosman111 | | #8

          The code does often defer to manufacturer spec. Have fun talking with your inspector about it. I have had a hard enough time getting my inspector to enforce the code as written, I can only imagine convoluting it with manufacturer installation details. You can always go to the state if you are that concerned about it and they can talk to the local official. It's sad though that the people who are supposed to protect you don't.

    2. nj_homeowner | | #4

      The bottom of the rough openings are not sloped. They have the "flex tape" on the outer half only.

      Why would the architect need to include in the plan details that are prescribed by the window manufacturer?

      1. Bosman111 | | #7

        I am in the process of building an home too, and was upset that the sills were not sloped. Seems like a stupid easy detail to do to make the house all that much more bulletproof, but the framer's work off of the architect's drawings and not the window manufacturer. This is something the builder should know and communicate with his framers, although most builders have a 1 year warranty or similar and dont care about their clients. Even if the window does leak, it will be 5-10 years before it shows any signs... long after they are not liable.

      2. hughw | | #11

        Often, an architect details things prescribed in manufacturer's instructions to make it doubly clear to a builder how something should be done. Even if that wasn't the case, it would be rare for an architect not to have a note somewhere on the drawings or specifications that "installation of all items shall be in accordance with manufacturer's instructions" or something to that effect. Often, it will be a general note..sometime a specific note for a specific item such as windows. By the way, where was the architect in all this? Why didn't he/she catch it? And if the architect is being paid for "administration of the construction contract" they should not approve payment.

  3. Bosman111 | | #6

    I agree with Malcom. Here is the installation instruction I found on Andersen's website given the information you provided:,87,152,67,64,51,141,137,9,213,19,40,103,193,138,218

    Aside from code requirements, the windows will likely not be warrantied if they were not installed correctly, and if the builder will match the manufacturer's warranty including any water damage from incorrect installation I would say let him do what he wants, just get in writing. But of course he won't agree to it, so give him the information and tell him to redo.

    If the above link doesn't work you can enter your own details to generate the document here:

    1. nj_homeowner | | #9

      Thank you. I have the install instructions, and it's clear they were not followed. I know I can try forcing my builder to redo them, but I'm wondering just how important these details are.

      1. Bosman111 | | #10

        I saw that after my post, I would argue they are really important. Water is one of the worst enemies of your house and your cladding system whether it is brick, vinyl, stone, or fiber cement will have water get behind it.

        If you think about it, a window fills a big hole in your house, how it is sealed is very important. Almost all windows leak eventually. The building code and window manufacturers understand this and have come up with ways not to destroy your house when this does happen.

        Here are articles from building science corporation:

        I don't know if it makes you feel any better, but my windows were poorly installed in my house with some openings not even being flashed (see attached photos). I decided not to push the issue because I didn't want to come off as a know-it-all which I have a tendency to come off as. I regret it. For the lifetime of my windows I will be keeping my fingers crossed that there are no problems and taking the gamble of a potential a $10k repair. I did have other issues like my trusses being ordered wrong (that I caught) that I was more concerned with at the time though, and didnt want to seem pushy. (I did make them flash the one window though) It is up to you. I think the whole building process requires you to analyze whether or not its worth it to push the issue. Windows are a huge expense though. I personally do not think it is unreasonable.

        I have included some pictures of the hack job that are my windows that might make you feel better, I'm just hoping that the 2ft hip roof overhang is my saving grace.

        I also included a picture of a product called suresill which you can find at the big orange store, if you were concerned about the slope maybe you could work it out with the builder to buy yourself and have him install. The product doesnt require wedge shims at the bottom because of how it is manufactured. I used this on my current house to replace 90 year old sheet metal pan for a door. It worked well. Amazing that almost 100 years later some stuff was just done better in the day. (this is for windows too) If you do do it buy an extra long piece (for sliding glass doors) and then buy extra side pieces. They drop ship right to you.

      2. Expert Member
        MALCOLM TAYLOR | | #12


        It's really difficult to predict if you will have any problems or not. So many things influence how vulnerable windows are to leaks. The climate, overhangs, the site itself, the quality of the workmanship on the siding, etc. They may be just fine. The difference is that if they had been installed correctly there would be no doubts.

        As to the code. I don't know which one you are under, but the 2009 IRC, R 612.1 Specifically requires window flashing to be installed in accordance with the manufacturer's "written installation instructions." and that "Written installation instructions shall be provided by the fenestration (windows and doors) manufacturer for each window or door."

  4. GBA Editor
    Martin Holladay | | #13

    I made notes on this code provision a few years ago. I assume that updated versions of codes include the same provision.

    Section 303.2 of the 2009 International Energy Conservation Code and the 2012 IECC requires: "303.2 Installation. All materials, systems and equipment shall be installed in accordance with the manufacturer's installation instructions and the International Building Code."

  5. spenceday | | #14

    Check your contract with the builder. Is there wording like ‘builder shall construct the building to meet (2015 IRC) code’? Pretty standard language in contracts I’ve dealt with.
    If there is, then you may have a breach of contract issue here.

  6. hughw | | #15

    and as I said in my comment above, check your architect's drawings/specificationsa for a note somewhere that "installation of all items shall be in accordance with manufacturer's instructions" or something to that effect.

  7. Expert Member
    Akos | | #16

    I might get a lot of flack for saying this.

    With a flanged window as long as the flange is taped to the WRB and the WRB is properly lapped at the top, it is a pretty solid install. It will be very hard for any water to make it past.

    Caulking the flange is mostly for air sealing, you can do the same thing by taping the inside of the window to the rough opening. This is fairly straight forward to DIY if the builder won't cooperate, easy to do it before the drywall goes in.

    Sloped sill adds extra insurance if the above details fail. It is cheap/easy to put in, but I wouldn't loose sleep over it.

    1. nj_homeowner | | #17

      The flange is taped, but with Tyvek housewrap tape, not thick flashing tape like Vycor Plus. Is that really enough for long-term durability?

      Is taping the inside really a substitute for caulking the flange? If so, that would prevent having to actually remove the windows for caulking.

      1. Expert Member
        Akos | | #19

        Tyvek is an acrylic tape, so it should be pretty sturdy. Lot of sheathing tapes don't look that beefy but hold up just as well or better than rubbery butyl tapes.

        Something beefier would be nice though, the Tyvek tape is pretty thin, something like the 3M flashing tape is about 3x thicker, just feels sturdier.

        The caulking behind the flange does also helps with water, keeps any water that gets behind the tyvec from getting into the rough opening. If you are in a high rain area, it is good detail to have.

        Reverse lapping the Tyvec above the window is not the best. The tape does help there provided it is installed properly and there are no gaps or wrinkles. The problem with a reverse lap is that if there are any wrinkling the water running down your WRB will now be nicely directed inside the window, which is not what you want.

        Kind of sucks that builders can't get simple details like this right.

        1. Expert Member
          MALCOLM TAYLOR | | #20

          Looks from the photos the OP added that the WRB is installed over the flange at the sill, rather than under.

  8. Bosman111 | | #21

    You may want to look at the installation requirements for Tyvek. Not only is your builder not following the installation spec for Andersen, but for Tyvek too especially with respect to the top flange of the window. Someone commented saying as long as it is taped to the Tyvek... this is incorrect if water gets behind the Tyvek (which it will because it is a staple applied product and they didnt use cap staples which helps with this[also a spec'd detail]) it will have a direct route into your home.

    I would have a HUGE problem with this since your picture shows a roof directly above that head flashing that is going to DUMP a concentrated amount of water right on the window. Gutters or not HUGE potential issue that your builder should be happy to want to avoid.

    That is the link to Tyvek's installation guide, it says for Tyvek flashing systems (which it looks like your builder did not use), but the Tyvek WRB installation manual references this guide. You are correct that tape is for sealing WRB to WRB primarily for Tyvek as an air barrier situation. Should be using pressure sensitive flashing tape.

    Here is the architectural binder for tyvek products. He should be using Tyvek Flashing Tape or equivalent. Flashing tape is stretchy so it allows for deferential expansion and contraction between dissimilar materials. Your vinyl flanges will expand and contract alot. Yes, that tape has a high quality adhesive, but it will break free as there is no give to the tape, there goes your seal. The 3M tape is a great tape, and yes it is "beefier" but its better because it stretches BECAUSE ITS A FLASHING TAPE. As cynical as I am about companies making a profit, Dupont doesn't have alot of incentive to make different tapes unless its needed. It would be a better selling point to have one tape that "does it all" as it is convenient for builders to just have one tape. Your builder simply wishes this was true.

    Also watch this video from building science prophet Joe Lstiburek important points at time stamps: (specifically talks about the head flashing)

    I would recommend watching the whole video, it is interesting.

    If discussing this gets you nowhere, don't get mad just call your inspector and relay your concerns. Hopefully they will help you out. If they won't help you call the building code office at the state.

    It should be a simple fix for him without the windows being caulked or shimmed. Should have taken the extra 30sec-1min to do it right.

    Also that scabbed piece of Tyvek on the rough opening on the right of your picture should be shingled ie the top of it should slide behind the WRB sheet above it.

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