Reproduction Exterior Doors with Insulated Glass

Advice about insulated, tempered, and laminated glazing for exterior doors, with some nice photo examples.October 17, 2011

I've made plenty of interior doors, but stayed away from exterior for many reasons. First I'll be making a new entry door for my own house - I figure it's the best place for a test door. I'll be for the most part copying the existing design, but modernizing it to add some insulation. Tired of the drafts!

The door is a Craftsman style with tall vertical panels on the bottom and an 8 lite section at the top. The individual lites are quite small at roughly 5" x 6" or so. I'm guessing it would make the most sense to use a single insulated glass pane and build a grill for the inside, right? I'm not even sure if they make insulated glass panels that small?

What do you recommend for weatherproofing seals?

Forum Responses
(Architectural Woodworking Forum)
From contributor D:
It'll be tough to temper those small openings - you'll most likely be asked if laminated is okay. Very small insulated glass units are stiff, and the volume of air between the panels expands and contracts greatly, and even more so if those muntin bars are stained dark and in the sun. This will eventually make the swiggle walk. On larger units the panes themselves flex in and out with the pressure difference. Single panes of course won't have this issue, but then you won't have the R factor of insulated glass. Our rule of thumb for tempering is roughly "can you put your fist through the opening?" Technically yours barely fits that rule, but for a single order with a guy cussing and cracking fifteen little pieces of glass to make one unit that small, I doubt anyone will want to take the order. Maybe if you made it worth their while, I don't know.

From contributor L:
Try Pemko for seals.

From contributor J:

When I queried a glass supplier about small panes for my front door, they were willing but there was a minimum charge per pane of insulated glass, no matter how small, so a single large pane would be much cheaper.

From contributor M:
For weather seals, etc., I like Conservation Technologies. They have some really good products. As far as the insulated glass, I think I would do as you suggest and not make it true divided light. It might also depend on how wide the muntins are.

From contributor O:
The jump from interior doors is a big one and sounds like you are taking a smart approach. I am a fan of historic door and window construction but insulated glass, code restrictions and heated, well insulated homes changes the construction technique of doors and windows considerably. While it is possible to build totally reproduction furniture, you would be hard pressed to build all doors and windows that way. We have an ongoing project building historic 5/8 wide TDL single pane putty glazed windows and storms for a customer's summer ranch property. This has been a great project, but if these windows were used in a year round modern home, they would fail in short order.

The biggest cause for failure in IGU is improper installation and blocking. As mentioned, the pressure buildup and small sizes make things difficult. The small producer not making IGU in-house is further handicapped. Another thing most shops don't consider is the condensation and leaking you get from the IGU and where it seals against the sash. This is more a concern with windows and bad exposure doors. We have drainage slots built into our window tooling to deal with this. SDL will give a higher R and U value and more resistance to water penetration in exterior applications along with easier glass replacement if done right.

We make the outside like a true divided light coped and doweled into the door using hard, rot resistant dowels. We have split door tooling with 5 profile choices that goes from 45mm thick up to 78 mm thick, so this is easy for us. The grill is made using the same cutters. We just set up a Hoffman dovetail router to connect the bars. I would just figure out a system that works with your tooling and joinery methods.

The last picture is an interior sliding shoji door that received etched glass. Those are thin TDLs coped and joined with dowels. The glass was coated with a film to meet code. That works well with art glass.

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From the original questioner:
Thanks. I still haven't decided what I'm going to do, but I don't think using the smaller insulated glass panes is the way to go. I have to say I'm not excited by using a single insulated panel either, in terms of aesthetics. I'm thinking of how it will look to see the backside of the muntins through the insulated glass.

Maybe I'll forgo the energy savings of the insulated glass and just recreate the door with true divided lites. I should still be ahead of the game by having the raised panels insulated, and by having a much better fitting and weather sealed door. Plus I'll be able to insulate between the jamb and the framing. Not to mention that currently there are gaps where you can easily insert a finger between door and jamb! It's really only a very small amount of glass area at the top anyway, so maybe it's okay to lose a small amount of R value to preserve the aesthetics... Or am I nuts?

The glass section is over 5' off the floor. Would it still have to be laminated or safety glass? I'd prefer to use an antique glass if I could.

The door itself will be painted a light color to retain its original look. It is also underneath a small porch roof so is not generally exposed to rain, snow, etc. except for the occasional Nor-Easter which doesn't care about overhangs.

From contributor D:
If you use GBG (grille between glass) under the bars, you won't see the other side. We can make it look just like TDL. The joinery is the same cope and stick, same profiles, whether it be applied or muntin bars.

Building codes require tempered or safety (laminated) glass in exterior doors and sidelights. Transoms can be regular annealed.

From contributor L:
They make the aluminum separator in a few colors. I know they do aluminum and bronze colored aluminum. They may do black also. That way it isn't shiny and very noticeable.

From contributor I:
I would also go with a TDL, insulated glass even if it's laminated safety glass. One nice upgrade which helps with glass and gives a nice heavy panel in a shaker door is going to a 2-1/4" door, but you need the proper tooling of course. (I have the same basic door on my house with beveled glass).

Weather stripping in my mind is broken down into a couple groups - new technology and old school. New tech is the snap-in Q-Lon type weather stripping with an adjustable aluminum threshold. This approach is definitely the easiest, works adequately, and is readily available. Old school is spring bronze or interlock on the jambs and an interlock threshold. This approach is more difficult to install and usually means some hand fitting of the door because there is very little margin for error, particularly on the threshold. This type of weather stripping is almost an art form and the products, while still available, are getting harder to find. Have fun with it.

From contributor B:
Not too long ago I did a Craftsman style exterior door. I used ash, because it was my best choice in matching the chestnut interior. I stave cored the door and laminated it with 1/4" ash veneers. I used West System epoxy for all the glue ups. The saddle was 8/4" white oak. I used kerf type foam weather stripping around the door and a bronze interlocking threshold on the saddle. I got the threshold from somewhere in White Plains, NY, I believe. The glazing had to match stained glass windows in the front of the house. I was able to get the stained glass laminated, and used laminated restoration glass for the center panel. Door was finished with spar varnish.

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