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Community and Q&A

Alpen vs Inline

52Dave | Posted in Green Products and Materials on


I am comparing Alpen and Inline products. I have recieved quotations from both companies and I would like to pose a few questions to those that have a little more experience in this relam.

Both companies use fiberglass frames and Cardinal Low E Glass. Inline makes their frame and Alpen purchases the frame material through Inline.

Alpen makes a double pane window, their 525-s Series, that have a whole window U-factor of .19 for casements and .15 for pictures. Inline offers a triple pane window with a whole window u-factor of .17 for a casement and .14 for a picture.

My questions are as follows:

Will I notice a difference in performace based on the U-factor numbers here?

Will the triple glazed soft coat windows provide any other benifits beside a slight performance advantage? Such as noise reduction, strength, etc.

I am debating a nailing flange or strap anchors, but am drawn to strap anchors do to the price. Will a nailing flange offer any benifits over the strap anchors besides ease of instalation.

Thank you for any input. I have simplifed the variable with my windows in this post., however, I would like to point out that my sothern exposer windows will be taking advantage of a passiver solar design.

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  1. 52Dave | | #1

    One more question.

    Due to the elevation of Alpen's manufacturing facility and the elevation I am at, northern CT, windows will include a breather tube attached to a ballon filled with inert gas. I will have to crimp the breather lines after windows arrive on site. Are there any detrimential effects with this detail? Is there a possibility of the gas escaping at an increased rate over factory sealed window panes?

  2. GBA Editor
    Martin Holladay | | #2

    The breather tube pinching is a bothersome detail, but it should work. However, it's one more thing that could potentially go wrong.

    The biggest difference between Alpen double-glazed windows with a plastic film and real triple-glazed windows is the uncertainty over the longevity and durability of the plastic film. In the past, these IGUs (called Heat Mirror units) had problems.

    Of course, U-0.17 windows will perform better than U-0.19 windows, all other factors being equal. It's hard to know whether you will "notice" the difference.

    As far as I know, triple-glazed windows will do a better job of noise reduction than double-glazed windows with a suspended plastic film.

  3. charlie_sullivan | | #3

    As far as the mounting details, that's affected by the type of wall you are installing it in, and, if it's a thick wall, where you plan to position the window--near the outside surface, the inside, or in between. If you provide those details, someone here might be able to give you advice.

  4. 52Dave | | #4

    Windows will be mounted on the outside of the original 2x6 wall assembly. Insilation will be mounted on top of the sheating, in a sense making an inne or in-betweenie window assembly. I have read different articles on GBA regarding the best method. I feel that the outie instilation is the easiest way about this, however, due to certain constraints, I am limited to using the other methods.

  5. 52Dave | | #5

    I have been doing some further reading on the advantages and disadvateges of each window design. Alpen suggests that triple pane windows are much heavier than suspended film variants. This additional weight impacts window performance by causing excessive wear on window harware and additioanl stress to the frame. The added stress can cause the seals to prematurly fail due to warping etc. I would like to know if these are valid concerns? They seem logical.

    Besides this, Alpen offers a Limitred Liftime warranty to the original homeowner for as long as they occupy the home. Inline has a 20 year limited warranty. On the flipside, Inline has a history while Alpen had gone under Serious Windows (If I am not mistaken) at one point. So the possibility of them not being around in the future is much more likely than Inline.

    Lastly I feel that the strength of the US dollar may be working to my advantage with Inline as I am getting a triple glazed window at pricing that is very similar to the double pane, suspended film unit. Performance is better, if only marginally, with the triple pane unit.

    If you were in my shoes. How would you proceed?

  6. jackofalltrades777 | | #6


    These companies change hands a lot and when the suspended film disaster took place in the late 1990's early 2000's the warranties were worthless as the companies folded. IMHO, warranties are marketing hype and most of the time if you read the fine print you will not get covered.

    As Martin stated, suspended film technology has had its major problems and failed windows. Triple pane is a tried and true approach. It simple because it uses 3 panes of glass, not fancy and complex technologies. The claim that triple pane windows are much heavier and the additional weight impacts window performance by causing excessive wear on window harware and additional stress to the frame leading to warping and failure is HOGWASH. Of course a company selling a suspended film technology is going to say stuff to sway you from triple panes.

    In Europe triple panes are the mainstay and they won't touch the suspended film technology. The risk vs reward is too high. Here is more discussion on the topic:

    What state are you located in?

  7. GBA Editor
    Martin Holladay | | #7

    It is true that triple-pane sash weigh more than double-pane sash. Reputable window manufacturers handle this fact by using heavier hardware or more hinges; this type of engineering or design issue happens with every product. It's a solvable issue.

  8. 52Dave | | #8


    I appreciate your input very much. That pretty much seals the deal for me then. I was leaning towards Inline as it was but the points you have made make it final. Thank you very much for your time and advice.

  9. jumanji | | #9

    I am very much interested in the information presented here. Have you received the windows and if so will you comment on the quality. We are building a new home and are considering Alpen, Inline and Zola.

  10. 52Dave | | #10


    I worked with Inline and was happy with the service that I received from them. From time of deposit to delivery was approximately 2 months. Windows were well packaged and I had only 1 issue with a jamb extension being damaged, although it was an easy fix. Overall, build quality seems superb, and I am satisfied with the product.
    There are a few issues that I am working to take care of at the moment, and I feel that a final inspection of the windows prior to having them shipped would have caught these issues. A few of the casement windows do not open and close as smoothly as the rest. In addition one of them does not open fully and I suspect that this is due to hardware not mounted properly. Being that Inline is not in the states added to shipping charges. On the flip side the strength of the dollar at the moment helped in keeping costs reasonable for the project.
    In summary, I would purchase from Inline again, however, would inspect the windows more thoroughly upon delivery to be sure nothing was damaged and everything worked as designed. I worked with Kamil Kostrzynski throughout the entire process.

  11. jumanji | | #11

    We are building a for lack of a better description a "traditional" looking home. In our area of southeastern Pa. it may be considered a Pennsylvania Farmhouse. That being said I am a little concerned about the width of the frame overall. Looking at the Inline website I believe the inside frame including the actual glazing frame is just over 4". I assume I can hide some of that with trim. I am interested in did this affect the aesthetics in your project?

  12. jackofalltrades777 | | #12

    I am pretty sure that Alpen does not make its own frame extrusions. From what I heard Alpen imports the fiberglass frame extrusions out of Canada. Could as well be Inline manufacturing that makes the frame extrusions for Alpen. Nothing wrong with that but just noteworthy.

    I believe Alpen bought out Serious Windows and the heat mirror technology a few years ago since Serious Windows was financially in big trouble. Serious Windows was also sued and fined by the FTC for false energy claims with their heat mirror technology:

    Alpen uses the "heat mirror technology" that uses the suspended plastic film IGU. I believe it is a Mylar film and only 2 panes of glass. Southwall Industries, Hurd windows developed the heat mirror technology but from what I read there were some issues with the technology failing and causing IGU problems in the windows. This was back in the late 90's. Since then I believe they re-engineered the heat mirror design.

    In my opinion, I believe a tried and true approach is 3 panes of glass. It's worked for decades and it's the KISS approach to energy efficient windows. Europeans have led the way in energy efficient windows and they won't touch the heat mirror tech with a 10 meter pole :) They stick with 3 panes of glass.

    The newly revised heat mirror technology could be perfectly fine and work for years without problems but I am not sure how long the new heat mirror design has been around. Three panes of glass is three panes of glass. Even if the IGU leaks, it's still 3 panes of glass.

  13. 52Dave | | #13

    William, To touch upon Peter's points first. Alpen told me that Inline manufactures the frames for them. You will have the same frame dimensions as with Inline. Peter is correct on all points essentially, the heat mirror technology has come a long way and Alpen stands behind their product in that regard.

    As far as aesthetics go, I have a contemporary home with a lot of tall thin casement windows, not very comparable with your situation. In any case, I do not find the frames to be obtrusive. In fact, one of the benefits of using pultruded fiberglass frames is that the strength of these is significantly higher than many of the conventional products used. This in turn should allow for a thinner frame and more area for the glazing/glass. I have a few very large windows and can say that comparing the construction of the existing wooden framed windows to the Inline units, the Inline product has a better frame. I hope I helped in clarifying the issue for you.

  14. jumanji | | #14

    Thanks so much. You have helped me quite a bit in thinking through this window purchase. As you are aware this is a big part of the expense of a new home and a critical one with consideration of energy efficiency.

  15. iLikeDirt | | #15

    For what it's worth, I installed an Alpen sliding patio door last year and have no complaints. It's a very solid unit that looks great, feels strong, and succeeds in keeping the radiant coolth off the inner glass surface in the winter. No problems with the heat mirror so far. Note: sample size of 1, take it with a grain of salt, etc.

  16. bunney | | #16

    I purchased Alpen windows and a high performance entry door for our home in North Central Minnesota zone 6, 46 degrees N. Passive solar. 1,320 square feet. Mine is a sordid tale when it comes to Alpen but also a story of hope.

    1. Typical turnaround from order to delivery, I am told, is 9 weeks during this year's building season. Our windows were still not available after about 11 weeks after ordering. Subsequently, the company upgraded us to the 725 Series that were available. I further negotiated upgrade of two windows to the 925 Series. Package includes fixed, casements, and awnings. One hitch. 8 of the elements in the windows available for delivery had flaws, ranging from imperfections essentially not visible to the naked eye to one broken pane. Meanwhile, our contractor was poised to de-mobilize resources (aka pull of the job) because of the delay.

    I took delivery of the windows as is. Yikes! Yup. That's the choice I made. Alphen claims that they will send a certified glazier, reportedly in mid-September, to replace the flawed units - without impacting performance, I am told. :-) or :-( Time will tell.

    2. I like that the casements have 3 locking points. Firm, tight, seal. The crank mechanism feels pedestrian to me. Clearly not a smooth working, highly refined hardware. Tough, long lasting? TBD.

    3. The sliding glass door feels a bit tight, but very solid when opening or closing. Does tightness equal well sealed? Perhaps.

    4. The entry door just got hung today. It's beautiful. It too has 3 locking points. The R rating of the glass is about equal to the insulated fiberglass door. Thus, adding a full length glass for the luxury of light in the entryway is a negligible hit in performance. I have yet to test how well the door operates.

    Epilog: My wife and I are well into our sixties. Neither of us have ever lived in anything remotely resembling a high performance home. We have fought the good fight on this construction -- constantly pushing and pulling against budget and performance. We have been fortunate to have problem solving contractor employees who have helped us find creative solutions all along the way.

    Will our Alpen windows kill our dream? I don't think so. Albeit long after I am gone our children may have a different view. Meanwhile, I fully expect to look out those same Alpen windows this winter onto a frozen wonder of lake, trees, and a Minnesota sky and be warmer, more comfortable than I have ever been in my many years of living northern winters.

  17. bunney | | #17

    Construction progress as of about one month ago. Tip of the hat too to Martin, Dana, and others who shared their knowledge.

    I forgot to mention that our windows got hit hard with stiff wind and golf ball sized hail several weeks ago. The windows frames did not suffer a single dent.

  18. jackofalltrades777 | | #18


    Keep us informed as to the progress and if Alpen steps up to the plate to fix the problems you are experiencing. As far as the hardware not being as robust. American window hardware tends to be flimsy when compared to European window hardware. I also do not like casements for the mere fact that they have a cranking mechanism that will surely wear out and fail. I prefer the European tilt & turn window that is basically a reverse opening casement but without the cranking hardware and gears. The KISS approach.

    The heat mirror is where I would be concerned. It's been re-engineered since the 90's and the failed units they experienced in the late 90's. Blame was shifted and placed but the heat mirror IGU's failed in a few short years. Time will tell if these new units will last the test of time.

    Maybe you can answer a question I have. Do these new heat mirror units still use a plastic piece that sits inside the 2 panes of glass?

    (I assume that the broken window in the picture is the one with the OSB covering it)

  19. wyobunney | | #19

    My Alpen window supplier called today noting replacement windows have shipped. He attributed Alpen's production delays and quality control problem this summer in part to Dow's purchase of Southwall, a company that produced Alphen's insulated glazing units (IGU). Dow bought the company for its suspended film technology..

    Dow reportedly gave Alpen one month to bring it's IGU production in-house before Dow shut down Southwall's production. My window order unfortunately hit Alpen during this period of Alpen bringing its IGU production in-house.

  20. Reid Baldwin | | #20

    I have been perusing Inline's website and find very little information about their glazing units. They have a lot of information about their frames, which is great. The pictures that show glazing units in cut-away all show double pane. I did find some U-values under the heading "passive house," which is consistent with the posts above. Am I looking in the wrong places?

  21. jackofalltrades777 | | #21


    So Dow bought out Southwall and the heat mirror technology and now Alpen will have to go through Dow in order t to use the heat mirror technology in their windows?

    If there are any problems with the Alpen window heat mirror IGU's prior to the buyout, who is responsible; Smartwall or Dow or Alpen?

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