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Overlay exterior doors?

maine_tyler | Posted in Green Building Techniques on

I am attempting to design/build an exterior door. It’s an experiment. 

My question is regarding overlay (i.e. European style) doors and how they differ.

I don’t have tremendous experience with door installations (I know, why try to build one you might ask ;)) and I am having a hard time understanding the fundamental difference in the overlay door.

What I do understand is that they close ONTO the door frame on all four sides (rabbeted), and that this requires some different hinging (barrel, post, or rabbeted?). What I don’t really understand is how this is different than the ‘stop’ an inset door closes onto. The only difference I can see is that the inset has some more jam available to attach regular butt hinges to.

How is this inherently different from a weather/air sealing perspective? Does it come down to where the rabbet is located (i.e. overlay has the rabbet on the door, whereas inset is rabbeted on the jam?)

Additionally, at the threshold, an in-swing overlay door would seem to rely completely on the seal to stop water entry (i.e. sort of a reverse shingle effect where the bottom of the door is lower than the exterior sill). Is there a detail here I’m missing?

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  1. Expert Member
    Peter Yost | | #1

    Hi Tyler -

    This is more of a woodworking question; must admit I had to look up the term. This helped:

    I am not sure why you would design an overlay exterior door. Can't say I have ever seen one. If I attempted this sort of exterior door, I would certainly protect it as a sheltered entryway, with a roof over it.


  2. natesc | | #2

    This makes me think of how the Shaker's mounted their doors. (attached a pic)

    Basically, build the door out of 5/4, attach it to 5/4 trim and attach the trim to the jamb. Door closes against the jamb.

    Much more efficient and easier to cheat things into place. The Shaker's were awesome at cheating. Kind of a tangent, but what is written about the Shaker's today seems a lot different than what I observed inspecting the stuff they built.

    Anyway, I am not totally sure this is what you were describing. If I was going to use this method for an exterior door, I would actually mount it on the inside and use an exterior storm door for the air seal.

  3. maine_tyler | | #3

    Thanks guys.

    It's true that it's more of a woodworking question I suppose. I asked here simply because overlay doors are touted by some to be the bees knees of air tight doors (common for Passivhaus European doors is my understanding). It appears some high end U.S. builders make them and also tout them as such.

    In honesty, I don't think i'll pursue it since I don't really grasp the concept behind why its superior at air sealing (if it even is). It was a case of, 'if i'm going in, I might as well go all the way...' But no sense in doin' somethin' just because...

    Nathan that looks like overlay I suppose. There must be something that allows them to be nice and water tight (extra overlap outside of seal at threshold perhaps) if they're used in high end applications. (No guarantee I admit).

    It also funny, Peter, that inset cabinet doors are considered a 'fine' fit for a cabinet, which seems to be the opposite of what's advertised for these so-called overlay exterior doors. Apples to oranges I guess.

    1. Expert Member
      MALCOLM TAYLOR | | #4


      Any chance of a link? They sound interesting.

      Our code has brought in requirements for three-point locks. That has pretty much precluded owner made doors, as you need specialized jigs to install the hardware. It has also added about $400 to the cost of each exterior door. They do feel secure when closed though. Paramedics easily kicked in my mother's door last week. I doubt they would have got through the three-point locks.

  4. Rob Myers | | #5

    I think that the main advantages are overall thickness (better insulation), multiple step seals so they are more airtight and multipoint locking. You can install your own multipoint locks but as Malcolm mentioned it is expensive - especially when you are only buying one. Hammer and Hand did a great video on one of the doors that they built. and you might find it interesting:
    Edit: Wrong link. The link above was a discussion. the build is shown here:

    1. Expert Member
      MALCOLM TAYLOR | | #7

      Rob and Tyler,

      Thanks for the links. Those are nice doors!

  5. maine_tyler | | #6

    Rob thanks for that! So it seems like adding a second rabbet on the jam goes a long way to ensuring the seal, similar to a single rabbet on an overlay door with double seals...

    I hadn't given too much thought about the hardware at this point. I'm opening a whole nother can of worms by attempting to do a french door sort of deal (double door) because its for a space that needs the wider access. Good to know the hardware install is of significance to feasibility.

    Malcolm, I'm having a hard time finding a lot of info on them- more mentions of them- such as in a Finehomebuilding article on building a custom insulated door in Vermont (not overlay). I also found a business based out of Colorado that does build overlay customs. Is it fine to link any 'ol website here?
    I'll do it and it can be taken down I guess if that not OK.

  6. Expert Member
    Peter Engle | | #8

    For PH overlay doors, the multiple layers of rabbets with gaskets do provide significant sealing benefits. But the real different (and benefit) is the lack of a sweep at the bottom of the door. Door sweeps are terrible for energy efficiency. The sliding action is hard on seals, which wear out quickly due to the friction and the grit and grime that is inevitable on a door sill. You also have that nasty corner transition between the compression gaskets and the sweep that really can't be sealed properly. The overlay doors just gently squeeze the gasket. With properly set and adjusted doors, you get the exact amount of squeeze necessary to seal the door without damaging the gasket.

    Yes, for an inswing door, there is some risk of water running over the threshold, sitting on the gasket, and dripping inside when the door is opened. In exposed locations, I have seem an extra flashing piece that provides a bit of extra overhang for the sill. Without any air movement between the bottom of the door and the sill, there's not much drive for water to enter that gap, and a slight pitch to the sill is generally enough to drain water to the exterior.

  7. Jon_R | | #9

    Nice explanation. So overlay vs inset is irrelevant to energy use - it's an issue of continuous (like a refrigerator) vs discontinuous/separate gaskets (top+side vs bottom). And in some cases, double continuous gaskets.

    1. Expert Member
      MALCOLM TAYLOR | | #10

      Overlay doors also allow for a thicker door with more insulation than inset ones. If an inset door is thicker than 1 5/8" they typically have to be bevelled at the lock side to swing into the frame.

      1. Jon_R | | #11

        Or increase the gap size to provide clearance. Which is that much more space that can't be insulated (so good point, some conduction energy impact).

        Similar for double gaskets. Seal/insulation/seal is better than a single seal, even if it has the same air leakage rate (as with walls and ceilings and both side air barriers).

      2. maine_tyler | | #15

        I'm assuming that the 1 5/8 " number you reference would really only apply to the edge of the door where it interfaces with the jam. In other words, the overall door thickness could be greater if the edge was rabbeted to make the effective interface thinner (such as in the double seals scenario).

        I never actually linked to the FHB article, but their door seems pretty nice and is inset:

        1. Expert Member
          MALCOLM TAYLOR | | #16

          Yes, just the lock side at the jamb. You can even have trouble with narrow (2'-0") interior doors with square edges if you want a tight fit between the door and frame.

  8. thrifttrust | | #12

    While the overlay design addresses the bottom sweep sealing issue, there is still a problem with the hinge side of the door. A seal design effective for the other three sides will not be compressed perpendicular to the gasket on the hinge side. That side's seal is conventionally designed to compress against the jam, not the stop. The transition between the hinge side and the top/bottom can be tricky. Just a heads up if you go through with building your own door.

    In Matt Risinger's latest video, he visits a build in Switzerland with an impressive tilt/turn door. It's multipoint lock has strikes on all four sides of the door. For security, I don't see the point of hinge side strikes. Perhaps they facilitate compressing a hinge side stop seal.

    Douglas Higden

    1. Jon_R | | #13

      Interesting. Never looked at it, but the hinge side of my front door has a different gasket that is partially on the stop and partially on the jamb (an L shape). The refrigerator (an overlay design) is symmetrical all around (it is also magnetic, which seems to help).

  9. maine_tyler | | #14

    Great things to think about here.

    The multi point locks all the way around the door certainly seems like it'd be effective. I can't help but feel like the complication weighs more than the benefits with such intricacy however. But that's just a gut feeling. For European manufacturers that have the process stream-lined it might make perfect sense. I couldn't see their hinging details very well, so there's still some mystery there.

    As far as threshold seals: Is there a reason a more typical inset door can't use a compression seal at the threshold rather than (or in combination with) a sweep? I could see it working especially well with the rabbeted and double sealed door design: the outer most seal (exterior face of door) could feature a flap seal to manage bulk water, creating a positive lap onto a sloping threshold, and the inner seal could run continuous from jams to threshold (all compression gaskets).

    I have seen mention of 'drop down' threshold seals ( which look interesting, but also complicated and still with issue at the transition from threshold to jam seals.

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