Insulated Core Entry Door Construction

Discussion and debate about how to build an insulated-core exterior door using wood. December 27, 2008

I've made many solid wood doors in the past but I now have a customer who wants an insulated, engineered stile, entry door. I don't have a big problem with that except that the door is two panels, both of which are raised. Would the panel be constructed from an insulated core, edged with solid, skinned on each side, and then moulded to produce the raised panel? This is a big door, 44 x 96, and I wonder about stability in solid wood. Is a stave core construction better?

Forum Responses
(Architectural Woodworking Forum)
From contributor T:
I'm not sure what you mean by "insulated engineered stile" door. Solid wood has excellent insulating properties in and of itself. I'm not sure what the R-value might be, but I wouldn't think you could improve it by using a structural composite lumber engineered stile.

From contributor D:
Insulating a wood door is redundant, repetitively so. Solid woods have a higher R-value, inch for inch than most insulation products, and they are structural to boot. Adding insulation is needless, and foolish to say the least. Having built many solid wood doors, I'm sure you know this.

Not to be offensive, but why does the customer tell you how to build the door? Does he/she know more about it than you? Or do they think you know less than they do? If you were to hire their profession, would you tell them how it should be done?

As for stability, it is the design of frame and panel doors to limit movement for stability. The stability comes from the quality of the materials and the craftsmanship of the build, as well as the experience of the maker. To suggest that at a certain size or weight warrants using man made materials belies a lack of confidence/experience in basic wood and joinery. Have you been reading those pesky metal or plastic door brochures?

From contributor L:

I've built doors with raised panels on inside and out, with Styrofoam sandwiched between (not glued). I usually use laminations for my rails and stiles (which helps control movement) and full mortise and tenon, haunched at top and bottom.

Plan out your profiles so your laminations don't show in these areas, and rabbet in a strip on the hinge and latch edges to hide them also. Depending on the door location, and your area, pay attention to water removal of the door, as in drip strips and beads which will direct water and protect the wood. Use a stable wood that is weather-resistant, and plan on maintenance of the door over time.

From contributor C:
While looking for an insulated wood core door I stumbled across this thread and was shocked at some of the statements. As an architect and craftsman few appreciate a solid wood door more than myself. The R-Value of wood is about 1.25 for softer woods and 6.5 for closed cell rigid insulation. With good windows coming in around R-8 these days, there is a huge need for insulated doors hat look nice. Keep on going with your search for an insulated wood door. The market is here!