A Treatise on Door Construction
Authentic Craftsman & Mission style Doors
Fine woodwork inspired by the designs of the Arts & Crafts Movement

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A Treatise on construction methods and material selection for Craftsman & Mission style doors

Doors are the opening statement of every home. They are the first and last thing we all see and touch as we
enter or leave a home. The quality and beauty of these doors set the tone for the rest of the home. This is particularly true in a Craftsman or Mission style home. In these homes
the visible integrity of the woodwork is of paramount importance. No other item in the home sees more use or is subjected to more abuse. The architects and home builders of the Craftsman Era understood this and responded by furnishing these homes with some truly timeless, traditionally constructed solid lumber doors. The term "Built to Last" really meant something as is witnessed by the thousands of these homes which are lovingly restored and cherished by their present day owners.

Today we are experiencing a renewed interest in the home designs of the Craftsman Movement. Some of these newly constructed homes are honest examples of craftsmanship and feature careful use of appropriate materials and details. As might be expected many of the new Craftsman style homes being built today fall short of the properties and characteristics which made the authentic homes so exceptional. I believe that this is due to a lack of understanding of what qualities actually constitute a real Craftsman home. To truly grasp this one
must examine the difference between "styled products" and products which actually feature authentic design and construction.

For literally hundreds of years doors constructed with mortise & tenon joinery were considered to be among the finest and longest lasting doors available. In the middle of the last century mass produced housing projects began to take form.  With this came the regular use of unskilled labor and building to the "bottom line". As a result the traditional trades
began to die off.
And along with this many of the time honored construction skills which had proven effective for centuries.

This period heralded the phenomenon of "disposable hardgoods". Suddenly it became accepted practice to furnish and install products which had a much shorter life span than
 the home they were being put into. To make matters worse much of the materials chosen for these applications were selected based only on a cost effectiveness basis. Little or no
thought was given to longevity or sustain ability. Doors, windows, cabinetry and trim were all heavily subjected to this treatment. And most homeowners are all too familiar
with the down side of this equation. Aside from the very real economic issues involved with early replacement of these items, it should be quite obvious to all that continuing
 this practice results in a shameful waste of natural resources.

Heart of Oak Workshop Door Materials
Our doors are always constructed using premium grades of solid lumber.
No fragile veneers to damage and nothing to delaminate.
Each piece of lumber is hand selected to insure that our customer receives the very best that Mother Nature has to offer. Years of experience allows me to confidently select only
 the most suitable boards for each door. And we offer only species that have appropriate characteristics for door construction. Woods like White Oak, Mahogany
& Vertical Grain Douglas Fir to name a few. Wood that has a high degree of structural integrity and resistance to decay.

Figure, straightness and density are just a few of the factors to be considered. After the wood has been selected it is then carefully milled to rough size and then allowed to "season".
This is basically a stabilization period. Cutting and milling by it's very nature often releases tension from within a board caused during the drying process. Most of the time if there is going to be a negative reaction this change takes place immediately. But it is prudent to allow a week or two for this to occur. The amount of time necessary for stabilization varies
 from species to species and sometimes board to board. This process is often overlooked by less experienced woodworkers and is absolutely critical to the final integrity of a solid lumber door.

No veneers, finger jointed cores or composites are ever used in the construction of our doors.
The use of these so called "engineered wood" products is extremely  prevalent in doors being manufactured this time. Many cleverly worded marketing schemes would have the
potential buyer believing that this is actually a better way to construct doors.  Well it is.....as far as the manufacturer is concerned. It is without question cheaper and easier to
construct with. With a fair amount of effort it can even be made to look quite natural and attractive. I can't help wondering if this isn't the ultimate in irony. Spending time and money on disguising the truth when the real thing will easily outlast the fake.

Detail of composite door material  
An example of one form of composite material

So how do composite wood doors hold up over time? What happens to the core if the finish is allowed to fail? And what happens when it needs to be refinished? Will I sand through the veneer or expose an edge? How is one species of veneer often glued to a different species of finger jointed core going to behave over time? These are all questions that every potential buyer should ask. Quite often the answer is as "muddy" as the heavily pigmented finishes applied to these doors to hide the truth of how they are actually constructed.

Some of the better manufacturers of composite wood doors actually go to great lengths to assure that their customers get a product that is a fair value for the initial purchase price. Others simply slap it together and hope it lasts the term of the warranty. Either way it should be obvious that this type of material will most likely have a much shorter service life
 than a good quality and properly constructed solid lumber door.

We do realize that the initial cost of the type of product we offer cannot always be rationalized. In the case of our solid lumber, mortise & tenon door the cost of material generally
runs 35% to 45% of the total sale cost. As you might imagine this is radically different from manufactured composite doors. Here a number like 10% to 15% of the overall cost is much more likely. So yes a composite door is likely to have a lower initial cost......but how many times will it need to be replaced during the life of the home? And how does it fit in with the basic principals of the Arts & Crafts Movement which is firmly anchored in the use of honest materials and craftsmanship.

Most certainly there are some conditions such as extreme weather exposure where a wood door of any type is not always the most appropriate solution. If you are faced with this
situation we would like to urge you to consider a high quality fiberglass or metal door as a responsible alternative to purchasing a composite wood door.

Heart of Oak Workshop Door Construction Techniques
It should be obvious to the reader by now that I am completely biased towards the use of Mortise and Tenon joinery for the construction of doors. This can be attributed to the simple
 fact that I enjoy building these doors and I intend them to last long after I am gone. I truly appreciate the opportunity to be working with fine woods and continually strive to build the very best doors available.

As a responsible craftsperson I feel that it is my duty to see that the doors I create have the longest possible service life.  My customers and the wood that I use deserve nothing less.
The doors I make are my legacy and I do not employ any of the joinery compromises that others may have accepted as adequate.

Over the years I have conducted rigorous testing and experimentation focused on the causes and prevention of joint failure. The end result is that I have no doubt at all that a
properly assembled mortise & tenon joint will out last any other method of wooden door construction. I am so confident that this is true that I offer all my customers a
Unconditional Warranty against joint failure on all the doors I build. It is all in the mechanics of this joint  and how well it is executed. Please read the sections below. I believe you
 will agree.

True Haunched Mortise & Tenon Joint
Shown : An actual example of Stile & Head Rail joint on one of our Classic Craftsman doors.
Please note that the tenon is an actual integrated element of the rail. Length of tenon is 2 3/4".
Photo of dry fit prior to actual assembly.

         Haunched Mortise & Tenon Joint

All of our doors feature haunched mortise & tenons which are glued and mechanically locked in place with pegs. This joint is clearly mechanically superior to all others in this application and completely resists the racking action that all door joints are subject to. It is the only joint that will hold together just fine without glue. It features a massive integrated tenon which extends into the mortise for half the width of the stile.

The primary reason that this method of joinery is not seen more often in recently made doors is that it is very labor intensive and requires specialized tools and skills to execute properly. Hand fit up is required and this should always be performed by an experienced joiner.  I personally perform this task on each and every door made at Heart of Oak Workshop.
I use properly set up square chisel mortisers which do not burnish the mating surfaces of the mortise.

In addition I use special tooling to saw cut the tenons. Here again no burnishing is created in this process. This sort of attention to detail is what sets our doors apart from most others. These joints are totally bulletproof. I have done it this way for many years and have literally made thousands of these joints. And not once has one failed.

A Classic Craftsman Entry door being dry fit prior to assembly

This is truly the only method of joinery that combines all of the characteristics  necessary to stand up to decade after decade of use without possibility of failure. Since we offer a unconditional warranty against joint failure we have taken the added precaution of using a high quality waterproof glue on all our doors. After all why not take advantage of the
largest and best shaped glue surface of all of the various door making joints.

A Greene & Greene inspired Entry System by Heart of Oak Workshop

All of the other methods of joinery used to make the critical rail to stile joint get the bulk of their strength from the glue that is used. And if for any reason the glue fails then so does the joint.  This is clearly not the case with our method of construction.
 Other commonly employed door construction joints include:

Doweled Butt Joint

Doweled Butt Joint  

This is a "butt" type joint of end grain to edge grain which is reinforced with wood dowels. It is a very easily assembled joint. It is totally reliant on the bonding strength of the glue used. To make matters worse the working surface area of the bond is quite small. End grain to edge grain has almost no bonding qualities. Any resistance to separation and racking it does have is centered on the glue surface of the dowels themselves. It doesn't take too much imagination ( or real life experience ) to picture the eventual outcome here. It almost always ends badly.

A recent episode of "This Old House" featured a segment of Norm Abrams and his approach to the repair of this type of joint. In a nutshell the door was completely disassembled and
 the failed glue surfaces were cleaned and re-glued. Then he drilled for and added huge lag bolts to help prevent future separation. The heads of the lag bolts where cleverly hidden in a recess covered with a wooden plug. I got a good chuckle from this whole operation as it was so obviously not the first time he had made this type of repair.
This joint has a well documented history of early failure and in my opinion should never be used to construct exterior doors.

One further note to the wise. I have seen many fairly high priced custom doors made using this method of joinery. It truly boggles the mind to consider why otherwise intelligent consumers would pay high prices for this type of joinery. I suppose the old catch phrase " Out of sight, Out of mind" applies here.

Cope & Stick Joint

Cope & Stick Joint  
 Variations of this joint are commonly seen in mass produced doors. It is made using high speed machinery  and is easily assembled using unskilled labor. In it's basic form it is a fair joint to use for smaller framed components like cabinet doors or windows. It has a relatively small glue surface area and is indexed in one plane by mating profiles. It is often nailed or screwed in place to resist racking during glue up. Another form of this joint used for door making features the addition of dowels as reinforcement. This should tell you something.
 It may be adequate for lightweight interior doors but should never be considered for exterior applications as it is prone to the same failings as all dowel based joints.

A slightly better form of this joint is employed in some higher quality products. This version has a relatively short (5/8" to 1 1/16") stub tenon which increases the glue surface area and helps to better index the rail to stile joint.  It is what I refer to as a "50%er". By comparison our doors feature  2 3/4" long tenons which offer more than  two times the glue surface area. What this all means is if a cope and stick door is well executed it is going to do fairly well for a while. Maybe 10 years or so. If it is well executed....if everything fits properly and it received the correct amount of glue and the finish is not allowed to fail.

Floating or Loose Tenon Joint

Loose or Floating Tenon Joint  
The term Tenon here is really a misnomer. Tenon implies that it is an integrated
structural element of the rail. While it functions similarly to a true tenon it is
clearly a separate piece and should be referred to as a spline

On the surface this would seem to be the best of the compromise joints listed here. This is a method of joinery which I have experimented with as it appeared to offer good characteristics. If it is properly constructed & assembled and mechanically pegged on both ends it offers almost as much strength as a true mortise and tenon joint. It should be noted that most of these don't actually get pegged and then it is down to the glue bond to hold things together. Unfortunately quite a lot can go wrong with this joint during fit up and assembly. Something you won't find out until it is too late.

My testing indicates that glue starvation is a big issue here. Beyond that many manufacturers mill the separate "tenon" improperly or make it from the wrong material. Additionally the mortises in this application are almost always made with a router or slot mortiser and the resulting mating surface is burnished to a
degree that a weak glue bond can result.  Anyone who has ever actually routed mortises in end grain (
such as the mortise in the rail shown above) will confirm this.

My evaluation of this method is that under the very best of circumstances this might be an acceptable door joint. I suppose that I would trust them if I had the opportunity to watch the door being made and be able to verify that all the necessary conditions have been met. Otherwise .... well I think I would have to pass as I am all too aware of what can go wrong with this joint.

I hope you have found this write up useful.
Jeff Balazs, Owner, Designer / Craftsman, Heart of Oak Workshop

Another G & G inspired Entry System by Heart of Oak Workshop

FLW * CFA Voysey * Mackintosh * Mackmurdo * Ellis * Gill * Ashbee
25675 Taladro Circle, Suite D, Mission Viejo, Ca. 92691

Tel. : (949) 461-9558       Email : heartoak@ix.netcom.com

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This page was created by Jeff Balazs.  All Photographs and Images are the property of Heart of Oak Workshop