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Patio door: I’m balancing options and need input, please

user-6990904 | Posted in General Questions on

Good morning from often windy Colorado, 7000 ft zone 6b,

We are building a pretty good house with a north facing patio that has a 9ft expanse for a door. There will be a covered pergola with some sort of clear material above for protection. We are looking at double slider, lift and slide, French with side lites and trifold. The windows will be Alpen.

We are balancing
A. energy awareness, aka air leakage
B. ability to get as wide an opening, aka my husband wants to bring the outside in
C. lost space from the swing needed from French or trifold
D. pricing

We have looks at both fiberglass and aluminum. We have priced Nanawall at about 8500, milgard Ultra fiberglass double slider at 5000, Sierra Pacific aluminum double sliders at 4700. And drum roll please Sierra pacific lift and slide 15,000.

Obviously have already read pieces posted including Martins recent post related to this and q and a.
Not exactly sure our price point but 15,000 is too high. We like the slide as the space on either side of the opening is not large so no swing space is good. But air leakage seems to be an issue with the sliders.

Oh one more thing, the local window and door retailer is excellent and gets rave reviews for follow up, he sells milgard, Kolbe, Sierra pacific, and others, Nanawall and others are about 100 miles away.

Thanks in advance for your wisdom. Please keep in my, I am a home owner, not builder and know zip.


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  1. Stockwell | | #1

    Call Cascadia Windows and ask about their compression slider. After an exhaustive search, that is what I am going with. The air leakage and water resistance numbers are excellent. The price would be less than the Sierra Pacific lift and slide but maybe a bit more than the Nanawall. Out of your choices you list, the Nanawall is most functional and performs as well as or better than the others(air and water leakage) if you get the WA67 with high performance sill. I got bids as high as $25,000 for my 12' opening(Kolbe). Crazy high and they didn't have outstanding performance numbers.

  2. user-6990904 | | #2

    Thanks for the feedback. Cascadia is not sold in my area.

    Just not clear what to,do...

  3. Expert Member
    Michael Maines | | #3

    Lydia, in a cold climate like yours, a large, north-facing sliding door is an energy sucker, and is at risk of being uncomfortable to be near all winter, so I would go for the highest performance I could afford. In general, swinging doors seal better than sliding doors--even lift-and-slide doors, in my experience--though some lift-and-slides are quite good. If cost and performance are important, and you don't want to use up floor space, I would consider a 3-wide unit with only the center operable, swinging back onto one of the other panels. Swinging doors often have wider frames than sliding doors, though, so assuming that monster opening is facing a nice view, you may not like the ratio of glazing to frame. A similar option would be one large, fixed unit, with a swinging operable unit next to it.

  4. user-6990904 | | #4


    OP here, thanks for the reply.

    In picking a brand, I see some folks refer to DP ratings. I am on the NFRC site right now and don’t see that. But do see U and VT of which I know. But also see condensation resistance. Have not clue if I want a low,or high number,for condensation resistance, or what a good number might be.

    Any suggestions or teaching appreciated. Lydia

  5. Expert Member
  6. Stockwell | | #6

    You want a high condensation resistance. Higher numbers are better. Triple pane will increase your CR. Numbers in the 60's are good.

    DP ratings and air leakage numbers can typically be found on manufacturer websites, though not always easily. Sometimes you need to look for "performance numbers" under the architects section or some other obscure place.

    Cascadia will ship to my NC address. They may not have local reps, but they will sell it to you.

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