Solid Poplar Versus Laminations for Door Stiles

Solid poplar has a good track record for door construction, but LVL stave cores may have their own advantages. June 8, 2008

I am a custom door builder and finish contractor. I am bidding on a large project of paint grade 2 and 3 raised panel doors with applied moulding. I am proposing to build with 3/16" to 1/4" lam poplar on LVL (laminated veneered lumber) stiles. My competition is proposing to build stiles out of solid 8/4 poplar, which I know is a drastic mistake. Milling and surfacing solid 8/4 poplar to 1/3/4" for door stiles in this woodworker’s opinion is asking for trouble. Poplar is just too unstable. I welcome everyone’s input.

Forum Responses
(Architectural Woodworking Forum)
From contributor S:
If it is dried, stored and prepped correctly, doing solid construction is not a problem. Not specifically a door builder, but we have done a few whole house packages and have not had a problem. If you store the boards on edge and leave air to all faces for a couple of days before face planing and surfacing, it works fine. Then after prepping, pick the best for the strike leg or pocket doors and the next best for hinge side crowning boards to hinge knuckle and the rest is left for rails and mid stiles. Never had a callback on interior or exterior door. If we did nothing but doors, I would buy stave core stock.

From contributor A:
Solid poplar works fine as far as twisting and warping. Once straightened it's not like it's going to start twisting again. The biggest problem is simple expansion/contraction on the 2 stiles. They simply swell more and can lead to binding doors. I have seen this numerous times on doors hung as pairs. In humid summers unless the ac is on, those stiles can grow substantially, thus binding the pair.

From contributor D:
I agree with contributors S and A. Solid poplar, of proper thickness and drying and machining, will make fine interior doors. The biggest problem is anticipating the movement, as in paired units. With thousands of doors out there, I have replaced a few poplar doors, but also a few white pine and a couple of others. Get good wood from a good dealer and process smartly. We always crown the stiles in each direction and make hinge and paired decisions while they are still stiles, as mentioned. There is nothing wrong with building the way you propose, but I don't know if the additional cost is justified in this situation. Maybe if your customer can only focus on "how wood warps all the time..." then it would be a worthwhile selling point.

From the original questioner:
Thanks for the input. I can purchase poplar stiles laminated on LVL for $40.00 to $50.00 a stile 4 3/4" x 96" x 1 3/4" thus eliminating any worry of warp as well as the labor involved in straight lining and machining inferior poplar. As an old door hanger, I prefer my stiles to be as flat as possible.

From contributor C:
You're probably right on track with technology and processes for this day and age. We also use 8/4 kiln dried stock properly jointed, sawn, and planed, to say dimensioned correctly and get a nice flat straight stile for less than you are paying. It relies heavily on good solid machining skills. A true jointer and proper training in each and every aspect of machining from rough lumber to finished stock ready for the shaper. When going forward to CNC machining of solid wood parts it will be even more important for parts to be true and flat for a good vacuum hold down. Enjoy your doors.

From Professor Gene Wengert, forum technical advisor:
In the past (like 1960s and early 70s), one of the main uses for yellow poplar (tulip tree or tulip poplar) was for solid cores for doors with more decorative veneer faces. Aspen poplar was often used for core in fire rated doors.

From contributor L:
Our office and restroom doors were made 20 years ago and are still fine, solid poplar S&R. We've also made hundreds of solid poplar S&R doors for commercial projects. Use your moisture meter! Your $40-50 stiles seem expensive.

From contributor G:
The Mona Lisa is on poplar.

From contributor M:
Seems there was recently a post on today's poplar versus poplar of old. Go engineered and take one less possibility of warp out of the equation. One bad door makes the price of engineered stiles cheap.

From Professor Gene Wengert, Sawing and Drying Forum technical advisor:
The Mona Lisa was painted on poplar from the Populus genus (which includes aspen and cottonwood). The discussion here is about tulip poplar (also called yellow poplar) which is in the genus Liriodendron and is not related at all to the poplar grown in Europe. The fact that the common name "poplar" applies to two different woods has indeed caused much confusion.

From contributor D:
Thanks Gene for the clarification. One thing for sure, the Mona Lisa is definitely in a controlled environment - no changes in temp or humidity for the poplar to respond to.

From contributor T:
" a controlled environment..." is a moot observation regarding the climatic stresses suffered by a 500 year old painting that Leonardo kept with him during his life's travels, and that was stolen and recovered 2 years later. Not much control going on until very recently.

From contributor B:
I always stave core my solid poplar doors. I don't know what your labor pool is like, but at $2 and change a bd ft a 6x96 stile costs me about $16 in material to make. They go together quickly and at the most, if I do a bunch, they are costing me about $35 a piece to make. Way under $50. Just food for thought.