Here is a thought provoking article on how to build exterior wood doors and gates based on storing and preserving lumber. A number of barns that we source lumber from haven't seen a coat of paint in at least 50 years. Some of them may have never been painted and most average 100 years old. How can this wood stay preserved and not rot?
If we are purchasing old lumber, we want to be sure that it recently came off the building. Almost every time that it sits in a stack with no airflow it will dry rot. Lumber that is stacked outside with stickers (wood spacers) between each layer to allow airflow will last much longer than a un-stickered stack with a sheet of plastic over it. The lumber that cannot dry out easily will begin rotting immediately. The same goes for an old barn. It can stand out in the elements getting beat with rain, wind, sun, snow, and anything else that nature throw at it. It will last for what seems like forever unprotected like this, but the moment it falls down it will start to decompose. We would rather have material that stood upright unprotected for a century than laid in the mud for one year. This can be so discouraging when we find old barns that are about to fall down from the stresses of winter snows. We offer to help take the barn down, but the landowner refuses. In short order, they fall into a heap and become a worthless pile of scrap.
We wish that we had more covered storage, but we simply do not have room to store everything under a roof. You can see that in this attached picture the stacks in our yard are stickered in a snowstorm. They will get wet, but the next day the wind will dry them out. When we bring our wood in from storage it always goes through a process of denailing, metal detecting, air drying, and finely kiln drying before being milled.
So, how do we recommend building gates or doors that are to be exposed to the elements? Customers often ask if reclaimed wood is tougher, more resilient, more stable, and drier than virgin wood. Some reclaimed lumber dealers may lead you to believe this, but honestly that can be a little bit of smoke and mirrors. Wood is wood whether it was harvested last year or a hundred years ago. It will still absorb moisture, rot, or crack. The biggest difference about older wood is that it came from old growth forest and on average may have tighter growth rings than fresh cut virgin wood. Also one can be assured that all of the green moisture is out of reclaimed lumber; the only moisture still present is ambient moisture which is easier to get out. Reclaimed lumber can still warp and twist in new ways, but if properly used it may not have the surprises that green virgin lumber may have. Finally, whichever kind of lumber one uses, they still need to take the same precautions to protect the piece that they are building. This means that using either reclaimed or virgin lumber one needs to plan ahead to protect the wood from the elements. Find more on door care in our FAQ or warranty.
Our standard way of constructing doors is with solid wood pieces that have multiple laminations to maintain flatness; see more on this in our door construction pages. Our joinery is very tight with close tolerances. This quality of craftsmanship is great if the door is to finish and protected from the elements. No amount of finish and maintenance, though, is going to protect a door from direct rain and sun. That door will soak up the water and the finish will peel off; for this reason your exterior doors need overhang protection. Occasionally we are asked to build doors and gates that will be exposed to the elements. First, we won't build a product that we cannot stand behind the quality, and we feel that it is important to manage customers’ expectations of how the wood will perform. If it is a door that does not lead to a conditioned space or an outside gate we recommend using solid wood boards and mechanical fasteners such as bolt and nuts. In these instances we recommend against using lamination or any glued joints. No matter how waterproof the glue is the wood will swell and move, and thus break the joint. To keep the door relatively flat wood braces can be bolted on (a nice touch here is to use authentic old rusty bolts) or an even stronger method is to introduce a steel framework. These solid wood/ non-glued plank doors are typically built with looser tolerances that allows for wood expansion or movement; they resemble the doors built for old barns.
In these non-laminated doors that are fully exposed to the elements we recommend against using any finish or paint on them. For the same reasons outlined above about how wood will rot when it is not allowed to dry, the finish will trap the moisture in the board. For example, if one were to build a fence with lumber, it would last longer with no finish ever applied to it than one with paint applied but not maintained yearly. No matter what the finish manufacturer's claims are there is no finish that lasts ten years or a lifetime like some claim. The wood underneath moves and cracks, therefore opening up new holes for moisture penetration. Also, no matter what the owner's good intentions of maintaining the finish, as time goes by it is often forgotten. We would rather use old wood and let it naturally weather with no finish. Let nature install it owns beauty, and the piece can look like it belongs in its spot. These non-laminated doors made with solid wood are sold as is with no warranty except that they meet the specifications in the proposal. We cannot warranty whatever nature might do. Remember this recommendation for no finish does not apply to our standard doors built with glued up joinery.