Exterior Doors and Sun Exposure

Another discussion about the beating doors can take from the sun, and how to protect against it. July 13, 2011

We have an exterior raised panel door to make. It will be exposed to weather since there is no overhang or screen door. I am in Ontario Canada, so we experience high humidity in the summer and cold dry winters. How should I seal the joint between raised panel and the frame of the door? Silicone after finishing? We will use West epoxy on the frame joints. The solid mahogany we are using for the panels needs to float.

Forum Responses
(Architectural Woodworking Forum)
From contributor L:
Exterior raised panel doors, no weather protectionů Not a very good idea! That said, about 20 years ago I made a set of them for my parents' house. I live in Nebraska where it's said "if you don't like the current weather, wait a few minutes." Below 0 to above 100F. Rainy spring, hot dry summers. The doors I made faced east onto a brick patio. There was a 3' overhang.

Construction: Honduras mahogany, 1 3/4" frames, mortise and spline done on a Maka mortiser, resorcinol glue. Since the panels would be subject to extreme differences inside to outside, I made an inner panel, then a thin sheet of plastic, then an outer panel. Panels and frame grooves were finished with several coats of urethane varnish. First coat was thinned 50/50 and the edges of the panels were soaked in it. The panels were finished the same all around. The molded area of the frame and the groove were also finished the same way. After assembly and fitting the rest of the frame was finished the same way, clear finish. I made every attempt at keeping the panels free to float, not wanting to risk a cracked panel. The back of the panels and door grooves were paste waxed before assembly. The upper area of the door has leaded art glass instead of a wood panel. Several years later a screen door was added.

It worked. Doors are still in good condition and have been refinished on the outside. A matching side light was also made the same way. I also made a new mahogany door frame and brick mold. A lot of labor!

From contributor D:
The panels need to float. Allowances can be made by determining the range of humidity/MC and using the Shrinkulator. Wider panels are far less tolerable of movement than narrow panels.

What type of warranty do you offer? Look up real door makers' warranties and see how they handle exposure situations. I think all would exclude the use as you describe.
While an experienced custom door builder can make a door that will last a reasonable time in such a situation, the initial expense and maintenance will likely inspire metal or plastic. Good design will include sheltered openings, and sheltered openings can be warranted. Economy is usually the cause of unprotected openings, and therefore may rule out the expense of a proper wood door.

From contributor N:
Put a full view storm door on it. It doesn't look as nice, but it will look nice much longer and have a much longer life.

From contributor H:
I have had trouble with panel doors in this situation. The full glass door heats up the wood (if it's in the sun) causing cracking, pitch bleeding, and paint failure. Not using a full glass door is worse. I think lead paint used to allow wood to be used in this situation, but the only thing we can do now is put up a porch roof, use a metal door, or accept wood movement and finish failure. Batten storm doors do work, but no one wants to cover up the man door.

From contributor D:
Full view storm doors unintentionally become solar collectors if the sun hits a door. This is made worse if the door is a dark color. I have seen surface temps at 185 degrees. If you use a storm door, it needs to have a 1/2" gap at the top and bottom to let out the heat. This usually does not go over too well with your customer.

As part of a larger discussion, one solution does not fit every need with exterior doors, hence the influx of metal and plastic doors as an attempt to find a one-thing-fits-all solution. While the artificial doors also have serious faults in service over time, they are so cheap as to offer appeal on that level. That segment of the industry is also united against the warp, crack, check and peel problems they see as inherent in wood doors, and trade on that in the marketplace. Since anyone can build and install a wood door, poor installations drive buyers to the artificial door vendors.

The root problem is poor design in the structure at large, since a sheltered opening is not provided.

From contributor T:
Don't disregard the storm door solution if you have a northerly exposure. But if your door will receive full solar exposure for a good portion of the day, the heat buildup will be tremendous, and that will lead to failure.

However, the steel door in the same opening will warp and twist just as badly as a wood door will (that's why they have a big old cushiony strip of magnetized refrigerator door weather stripping around the perimeter).

If you stick with the wood door option, just remember that it will require regular maintenance. And a single panel will expand more than two smaller panels, and quartersawn material will expand less than flat or plain sawn.

But regardless, expect a service call at least twice a year as the seasons change.

From contributor D:
As a sidebar to the heat buildup topic, when I was learning the trade in the early 70's, the shop I worked in occasionally reproduced plastic plant-on moldings from metal doors. The moldings had melted from some intense heat. I was given the task to reproduce the moldings and curves and assemble to go back onto someone's door. I assumed the melting was due to fire.

As summer ended, we were doing a couple of these jobs a month, and I remarked that there must be rash of house fires. The wizened old foreman smiled his wry smile and shook his head, and walked away. Only then did my coworkers explain to this new kid that the plastic melted from the heat of a storm door, not a house fire.

From contributor T:
Ditto to what contributor D said in the previous post. I too have seen the melted plastic moulding of a steel door behind a storm door. I have also burned my hand from touching said door. Wood doors are a much cooler option, and a good natural insulator also.

From contributor B:
We've done a few of these now and seem to have had good results. We make a raised panel for each side with a rigid foam core in the middle. Get a tight fit on total depth and leave room in the field for expansion. We're in Ontario so I know it can be done. That said, there's no doubt that wood doors, even well made ones, take a beating with total exposure to the elements. Make sure the client is aware of it.

From contributor N:
I have had good luck with the full view storm door and natural finished white oak
(southeastern exposure on the bay). The other option with a clear finish is yearly refinishing. A door that gets direct sun all day is going to have problems anyway.

From contributor D:
I would strongly consider a lighter door than mahogany. I run a custom door shop, and in my experience, tight grained (at least 16 rings per inch) VG Douglas fir is about the best performer in direct exposure situations. Yearly refinishing with UV resistant spar varnish is a pain. Frequent oil finishing, while not as water resistant, is easy and actually develops a patina that looks better with age. Fir soaks up oils better than white oak too. I don't know why it works, maybe because there is no hard finish to crack, and maybe because it penetrates deeper. We have many contractors who buy from us that offer these yearly oilings as a maintenance agreement. If the homeowner doesn't take them up on it, at least they are now more keenly aware of the importance of maintaining their new door. Some of these contractors, according to ours sales staff, buy Doug fir doors only.

From contributor Y:
A wood door, of any material, exposed to the weather, will have problems. I agree with all the advice posted here. The panels should be laminated in some fashion to avoid splitting all the way through. I have for many years made 2 panels and placed them back to back. This lets them float individually to the exterior and interior temp/humidity conditions. Part of your question was about sealing against weather. A standard raised panel set in a groove tends to shrink and let in water, starting a sequence of swell/shrink/rot activity. Finishing before assembly will help. A paint finish seems to hold up better than a stain. A stained door is like a wooden boat, requiring frequent maintenance.