Raised Panel Shrinkage

Cabinetmakers grapple with the issues raised by installing unfinished cabinetry in an unheated house, mid-project. May 28, 2010

I am having a problem with my raised panel doors shrinking! I use mainly poplar and soft maple to create my raised panel doors. I only use these materials in order to be competitive in a tight market. I realize that the materials are part of the problem, and that some shrinkage will occur will these soft materials. As far as I can tell, I actually have two main problems. First, I have a 5,000 sq ft shop that is difficult to heat (especially at night); so, the materials are not temperature controlled the way I would like them to be throughout a 24 hour period. Second, my builders push for my cabinets, and I run into unheated homes on a regular basis. I have demanded that the homes be heated before I set the cabinets, but as many of you out there know, this is not always the case. In other words, it is difficult to demand anything from your customers. Inevitably, I will set the cabinets in order to appease my clientele, and inevitably, the panels will take on moister while waiting for the painters. Once painted, the moister is trapped, and once the job becomes temperature controlled over time, the panels shrink.

I have suggested to the builders that they let the cabinets reside on the job two weeks in a temperature controlled environment before the painting/staining process begins, but the time factor is the issue for them. So, after the prospective client buys the house, and time passes, they look to me for answers. All I can tell them, is the temperature in the house was inadequate when the cabinets were set. As many of you out there know, playing the blame game does not get you very far. Is there anyone out there that has been able to resolve this issue effectively? I was thinking that if I created an area in my shop that was heated to 150 degrees (standard kiln dried temperature) that possibly I would be able to shrink the panels before they left my shop, and that the panels would be fully shrunk. As you can see, I am grasping at straws here, trying to find an answer that does not include relying on my clients. I am tired of having the painters point fingers when I feel that the builders are to blame for the problem. If anyone has had this problem in the past, I would greatly appreciate a response.

Forum Responses
(Cabinetmaking Forum)
From contributor J:
I'd first move these trifty types over to a poplar frame with a MDF panel. That should eliminate about 90 percent of the problem, and yield a better finish. Second, are you using spaceballs in the doors, and adjusting the fit to reflect the humidity level? Third, after recommending they control the temperature and moisture conditions in the house, I'd relinquish liability to the builder at install. If pressed on the issue, I'd delay install until the climate control is in operation. Stall the builder's King Ranch or deer lease draw with that one, and next time the heat will be on. Others could probably shed more light on the moisture level at install. I think you should be more concerned with moisture than temp. One step you could take is to prime or stain the panel edges prior to assembly, of course that would require forethought on the part of the builder to give you a color.

From the original questioner:
I would love to move over to a trupan (MDF) panel, but most of my trifty builders like the option to stain or paint the poplar; thus eliminating the possibility of an MDF panel. I do use door spacers in my doors, but I am not sure how to adjust for the humidity levels. Any advice on how to achieve this? Good call on holding the product and stalling out the job until the builder gets the point. Of course, the fear is that the builder will find another woodchuck to take this woodchuck’s bread and butter. That being said, I am very close to playing that card with several of them. I have gotten some of my clients to listen for a short period. Then it’s back to the same sad story. If I could only get the builders/designers to have the foresight to pick a color/stain before it was right on top of them. Then they would have to change professions and become subs. Thanks for the advice. Let me know something on the humidity and size change if you get a chance.

From contributor J:
When you say the panels shrink, how much do they shrink? Is the problem that the paint/finish film gets torn? That unstained areas become visible? I hope the shrinkage isn't so severe that the tongue pulls out of the groove. You would be in a better position if you knew exactly where the problem was originating. To that end, you should pick up a couple of hygrometers so that you know the humidity levels in your shop. You should also be checking the MC of your lumber. That will at least help you to be sure you're delivering a quality product. It doesn't make sense to look for fixes until you're sure where the problem is.

From contributor H:
Wood shrinks and expands due to moisture, not temperature. To get a handle on what's going on, you must know the MC (moisture content) of your material, and the *humidity* at the site. You should read up and learn about EMC (equilibrium moisture content) - you'll start to understand how to predict wood movement. Below is a link that will call up many articles in the Knowledge Base that covers this issue.


From contributor E:
Good advice about moisture content. Buy a good moisture meter and check the MC of a panel that has shrunk after being in one of the houses. After checking a few of these call-backs, you will see what MC you need your lumber to be at before you mill and assemble your doors. Maybe your supplier is sending you wood that is at too high of a MC. Find a different supplier that will guarantee their MC within a certain range. Even if your lumber costs more, the money saved on call-backs and re-work will be substantial. Another option would be to remove the doors from the cabinets after installation and hold them until the house is heated, or have the painters do them in a heated location.

From contributor T:
Our contract has a line in it about heating the house before delivery. If this not done then the warranty is void. Also a good moister meter was one of the first tools I bought when starting out. When bidding a job I always take moister readings on site and record them.

From contributor D:
Putting unfinished wood into a house under construction is the risk, beyond what the RH is in your shop or the MC of your lumber at arrival at your shop or on the job.Concrete work, plaster work, paint and other trades all put huge amounts of moisture into the air. If the house has the heat on all that means is that the air has a higher capacity of moisture in it. You need to know what you have in the shop, and what you need to have on the site. You must exhibit good practice if you want your customer to do the same. A stable RH is the only thing that will protect unfinished wood. Finish will slow down moisture exchange, but not eliminate it. Watch a good hardwood flooring outfit. They will read the MC of the subfloor and RH of the house and insure it is stable before they store the flooring on site for two weeks before laying.

From contributor R:
Why not suggest to builder, to put plastic over kitchen doorways, and run a de-humidifier a couple days before the panel is caulked. If the builder is having the painter finish the cabinets seems that is the painters problem, just have the cabs dry at finishing.

From Gene Wengert, forum technical advisor:
It is 100% a moisture problem (relative humidity of the air is drier than the moisture content of the wood) that causes shrinkage. Are the raised panels free to float and fastened only at one spot, if at all? If the MC of the wood is proper and your shop is also ok with respect to humidity, then wrap the cabinets in a plastic bag so that the MC will not change until they are unwrapped. Put a big red tag in the bag saying "Caution: This is a wood product that is sensitive to moisture changes. Do not expose this product to relative humidity outside the range of normal living conditions (30% to 50% RH) as that will void the warranty. Etc."

Note that if you do get a moisture meter and then you use it to check the MC of wood after a crack appears, you will find that the reading will be a low moisture reading. That is, the high moisture was present before the crack and then it left and as the moisture left, the wood shrank. So measuring moisture after a problem occurs will give you a low reading and leave you wondering what is wrong. The MC must be measured before the problem occurs in order to get information on the cause of the problem. Because the moisture content measurement is so important, you should plan to spend no less than $200 on a moisture meter to get accuracy, resolution and reliability. This $200 is a small cost to pay to eliminate a problem.

From contributor R:
Can't believe anyone hasn't asked the obvious question. What kind of finish/paint is being used out on the job? I installed a paint grade maple job last month in which a jobsite painter was to finish. I went by the job after painting and noticed all the pair doors were lapping over each other at least 1/8" (left them with a 1/8" between at install). We do pre-finish at our shop so I was interested to talk with the painter in what materials he used. He told me the paint was all water base and the job had taken about 15 gallons of primer and paint combined. It occurred to me that my cabinets had been saturated and allowed to dry with that much water. No wonder they swelled. When the heat and air is put to these cabinets, after move in. they will also shrink back. What a mess. I'm afraid with the push to latex products from solvent based products we will see much more of these problems.

From Gene Wengert, forum technical advisor:
Contributor R makes an excellent point. But it can be more than water-based paints that adds water. As mentioned, dry walling, wall painting, and no-heat (65% RH would be common or higher, which is 12% EMC for wood) also can add moisture. It is for this reason that it is common to see the insert panel to be finished before it is put into the door frame. This will prevent the white streak from appearing as the panel shrinks. The frame shrinks so little that the frame is basically stationary or fixed in size. Also, note that there is no finish that effectively seals the wood or protects it from moisture changes when the RH changes.

From contributor K:
Ready to assemble my first set of raised panel doors as I recondition our kitchen and I am concerned with all the talk of moisture. Is it possible to put sealer on all the surfaces of the panels, rails, and stiles except for the glue areas before assembly. The wood is hard maple and will be finished with General Finishes polyacrylic.

From contributor H:
There have been instances where I've had the panels pre-finished in anticipation of overly-dry conditions (in a house with a wood stove). In my opinion, it's the panel movement that's the issue, not the rails and stiles. Pre-finishing those is a pain, and won't result in any benefit as far as future shrinkage is concerned. One other note I do remember a job I did where the cabinet doors (maple) must have been assembled with the wood being too dry. We installed the kitchen in the winter/spring, and when summer came around (higher humidity), the panels swelled so much that they actually blew the door frames apart. Moral of the story - know what the MC is of the material you're working with before you assemble doors.

From Gene Wengert, forum technical advisor:
A raised panel is usually put into its frame with small rubber spacers (called space balls) to allow for some swelling (but as mentioned, if the swelling is too much, then the frame can separate). The balls also allow the panel to move without making a rattling noise.

From contributor K:
I was basing my question on what I was told about interior doors about 40 years ago. If you cut one or plane an edge, put sealer on it. Also, our original custom made oak cabinets are flat panel. They were built in 1971 and we have never had any noticeable swelling, separation, or warping. Can any of you guys comment on gluing after sealer has been applied? Would it work? I also plan on using the space balls.

From Gene Wengert, forum technical advisor:
Most woodworking adhesives will not bond to a finish or wood that has been finished. Some will bond to the finish, but the finish is not strongly attached so the joint will fail when the finish pulls off.