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Fiberglass vs Vinyl Windows- Inline, Alpen, Aluplast

DanShow | Posted in Energy Efficiency and Durability on

Looking for advice, experience, and thoughts concerning our window options for our home build. We are making final material purchases and windows have been something we have gone back and forth on since early this year. 

Little background on our build: Climate Zone 5, rural location, single story build on a full basement. All of our window options are for triple pane either casements or tilt/turn operable windows along with the remaining units being fixed. All the window options are very similar from an energy efficiency standpoint. The Alpen units we are looking at, are their True Triple glass option, rather than the heat mirror option. All things are really pretty equal between our different window options including the price and lead times for our 16 unit package.

My major question is about which frame material we should go with, the Alpen fiberglass casement  option is the most expensive of the 4, with the Aluplast vinyl tilt/turn  and the Alpen vinyl tilt/turn options being in the middle, with the Inline fiberglass tilt/turn or casement  options being the cheapest. From a lot of the reading I have done here on GBA, fiberglass seems to be the more durable, stronger, and more energy efficient option, but I have also read about the weakness of the mechanically fastened corners on fiberglass frames being prone to leakage and eventually some lawsuits. (I am no window expert, so I am looking for others advice on this point.)

My second major question is which operation (either casement or tilt/turn) is more durable and less prone to maintenance issues.

Additionally any advice or comments on the customer service, product quality, etc. of Alpen, Inline, and Aluplast (which we would be getting from Hawkeye Windows and Doors out of Iowa) would be very much appreciated.

Thank you

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  1. ERIC WHETZEL | | #1

    My basement windows are uPVC/Alu-clad, and we've been very happy with the units so far. This combination seems like a good balance between cost and exterior durability. Do any of your options come with this combination?

    Although we have Unilux windows and doors, Larry, the owner of Hawkeye, was incredibly helpful when my Unilux rep proved useless when getting me a replacement part. I go into the details towards the end of this blog post:

    Larry didn't have much financial incentive to take the time to help me out, so, presumably, his paying clients enjoy an equally high level of customer service.

    Having lived most of my life with American windows, double-hung and casement, I much prefer the European-style tilt/turn function. I would be surprised if a casement window, even with triple pane glass, could match the performance and durability of a Passive House level tilt/turn. Aesthetically the tilt/turn function seems superior to me, but obviously personal preference plays a part as well.

    Beyond just performance numbers, arguably the most important question to answer is who can you rely on during and after installation should issues arise? If they're responsive to giving you a detailed price quote, give timely responses to questions as they come up, and they let you contact recent clients, you'll probably end up very happy.

    1. DanShow | | #8

      Thank you for the response and I agree with many of the things you have mentioned. Alum-clad uPVC windows are not something that we had looked at as those were outside of our price range. It was actually your blog that pointed us in the direction of Hawkeye windows. It also helps that we are located in the same state as them as well.

  2. ajc_electric | | #2

    I have the Alpen tilt turns and so far they seem good. Operation is smooth accept for the tilt and glide slider. Windows miter edges are noticeable. Last winter it was highly noticeably warmer near all the windows compared to 1995 Harvey’s double hungs.

    1. DanShow | | #9

      Andrew, thank you for the response. You mention the windows' miter edges being noticeable, do you feel that is a negative?

  3. anonymoususer | | #3

    A year ago we bought maybe 20 or so fiberglass frame casements from Alpen (zenith series) to replace the orig single panes on our 1949 Cape in Massachusetts. This year we contacted Alpen, Inline, Enerlux, comfortline fiberframe for a quote on a second batch (for different portion of house). Customer service let us down with all companies *except* ComfortLine Fiberframe. The customer service at ComfortLine Fiberframe was superb. The salesman we dealt with—Tom Mehrman—was sooo responsive and helpful. It cannot hurt to look into this company b4 moving forward.

    1. rondeaunotrondo | | #5

      Fiberframe in OH? Did you have them shipped from there? Did you happen to call EAS?

      1. anonymoususer | | #6

        I dont know what/who EAS is but the ComfortLine Fiberframe company I am referring to is yes, based in Ohio. I believe they quoted $1600 for shipping 18 or so windows to our Massachusetts home from their Ohio plant.

        1. rondeaunotrondo | | #13

          European architectural supply in Acton, MA.

    2. DanShow | | #10

      Thank you for the response. Who were you working with specifically at Inline and Alpen? Reps that we have worked with at both companies have been very responsive.

  4. brp_nh | | #4

    I can't answer your specific questions and have only been involved in one house build, but we have Alpen fiberglass windows in our house, zone 6 (NH). They are the 525 series (now called the ZR-5) in a mix of casement, fixed, and a couple awnings. We bought them from a great dealer in ME (Pinnacle Window Solutions) and the windows were installed in late 2013.

    We have been happy with the windows and they perform well in our harsh winter climate. I like that the screens are on the interior. We had a piece of the locking mechanism system break on one window, but it was replaced free of charge via our dealer.

    You can see some photos in various posts I wrote for GBA:

    1. anonymoususer | | #7

      Brian, the Alpen zenith 525 windows, did you opt for true triple pane (ie, 3 layers glass) or 2 layers glass with Heat Mirror film?

      1. brp_nh | | #14

        We have 2 glass layers with heat mirror film, I'm not sure if triple pane was an option when we purchased them in 2013.

  5. Expert Member
    Joshua Salinger | | #11

    We have installed the Alpen ZR6 on the last two builds we have done, I have one in my personal home and we are about to order some more for an upcoming retrofit. The only complaints I have had with the windows were the quality of the paint on two of the orders and how hard they are to lock shut when they first arrive.

    To Alpen's credit, the customer service was quick and they took care of the entire re-painting of the windows free of charge. The sub they hired to do it was slow in getting to them, but that had nothing to do with Alpen and the ultimate finish was just as good as any new window. I know they have also recently re-tooled their shop and have upgraded their painting process. In regards to the difficult locking mechanism which a number of our clients couldn't even open their window, again the service was good and they quickly got us information and an offer to adjust them. In the end they operate and perform well.

    I will put in my 2 cents and recommend fiberglass over vinyl for not just environmental reasons, but also how they hold up to better to UV over time and can be painted any color with typical latex paints should one's home ever need painting or updated colors. I haven't heard of or experienced the corners of the frames leaking...

  6. jackofalltrades777 | | #12

    Supply chains have been tough for all window manufacturers due to the pandemic. Kitchen cabinets are running 12 week lead times, which is insane.

    Alpen makes triple pane in either 2 glass panes plus the heat mirror or 3 glass panes with thin glass on the inner pane. Fiberglass (Zenith) is great for long term durability and its expansion rates are equal to that of glass. Alpen also has a PVC/Fiberlgass hybrid line Tyrol (Rau-Fipro).

    Either line would be very durable. I think it's more of a matter of choice whether you like American window frames or European style window frames. Performance is pretty identical in both lines. Alpen is based in Colorado so it's nice that they are US based and not importing from another country.

  7. DanShow | | #15

    Thank you for the response. The ZR-5 windows from Alpen are also ones that we are considering. Also the photos and article from your build, were excellent, thank you for sharing.

  8. DanShow | | #16

    Peter and Josh,
    Thank you both for your responses. We did go with the Alpen Tyrol True Triple Series units. Estimated delivery of late August.

    1. KGD123 | | #19

      Hi Dan,

      I'm building a house in NY state and considering Alpen Tyrol Ture Triple series. Are you happy with the product?

  9. rootsbuilder | | #17

    Don’t go with inline! You get what you pay for, their quality is low, customer service lower. I think tilt turn is most appropriate for heavy triple panes.

  10. sheropod2 | | #18

    I was the air leak tester for a house that was built recently. Alpen windows were selected and installed. Initial air leakage was around 1.9/50, and it turned out that there was substantial air leakage in the fixed side of the sliding doors. Air was able to flow between the frame and around the glass edge. I could feel it with my hand, and the smoke pencil showed a definite flow when held against the glass at the frame edge. I did both a pressurization and depressurization test, and the results improved when I pressurized with those joints taped. I believe the windows were defective but the owner decided that 1.95 was acceptable and didn't want to wait for replacements.

  11. dan_from_toronto | | #20

    Hi Forrest Twombly, can you please elaborate about the Inline windows?
    I have a quote from them and I am almost ready to order 13 windows.


  12. AC200 | | #21

    I was wondering the same thing, but Forrest has posted that in a couple threads without details. Inline make fiberglass pultrusions for many companies including Cascadia (who are generally well regarded) The IGUs are from Cardinal and mechanisms from Truth. These are common parts that are used by many window companies so I'd be interested in the details from Forrest as well.

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