Replies

1. 
   RalphBarker | Jan 08, 2011 12:14pm | #1

   thoughts, lite

   I would think the lites should be dual-paned. In a similar pane-vein, how about dual panels with insulation in between? That might require thicker rails and stiles, so you might need to add some other decorative treatment to "lighten" the look of the door.

2. 
   SteveSchoene | Jan 08, 2011 07:23pm | #2

   Being on the north exposure is a plus--better if is also under a canopy.  That's about the only place where you can keep a clear wood finish without constant maintenance--it will likely require only a refresher coating every other year.  But if there is any direct sun, plan on regular maintenance--annual refreshing with stripping and starting over every 5-6 years or so.  The clear finish to use is a marine spar varnish.  Marine means made by Interlux, Epifanes, or Pettit.  If you can buy it at a big box store it isn't really marine spar varnish, regardless of how nautical the name sounds. 

   A light colored paint works well, and is much more durable than varnish.  Paint would allow wider range of woods, brining in woods like douglas fir.  .   You should also explore the options in fiberglass doors.  Well finished they can look quite decent, and typically offer more insulation and durability.  There are many more styles available than you will see displayed locally. Way cheaper than most wood door options, expecially if insulated. 

   If you don't like white oak, then mahogany is the other good choice walnut heart wood also works well as an outdoor wood, though finding clear walnut would make that a pretty expensive option..   I suppose ipe would serve, but it is very heavy, expecially when bulked up to allow insulation. 

3. 
   PSeverin | Jan 08, 2011 08:26pm | #3

   A matter of proportion.

   The R value of any wood you pick will not make much of a difference in the overall thermal performance of the house.   More important for heat loss than R value is the weather stripping and preventing air infiltration.    

   It is always a little humbling to do a heat loss calculation on a building.   Modeling heat loss is a process of multiplying each area of the building construction, ceiling, walls, rim joist, windows etc by it's composite U value which allows you a number to see where the greatest heat loss is.  I suspect changing the "R" value of the door over the 20 or 25 sq. ft. of the door will not make much difference.   Or plugging a 1" hole in a roof won't make nearly as much difference as patching a 5-0 opening in keeping the rain out.

    LEED is a weird beast and you'd probably get more credit by repurposing something like a ping pong table into a door, installing a bike rack or building within 500 feet of three urban bus lines as you will from the buildings thermal performance.   Studying for the LEED exam I was startled by how little had to do with thermal performance and buildings.

   Peter

4. 
   acornw | Jan 09, 2011 02:05pm | #4

   If you are serious...

   If you are serious about heat retention and Leed points, then choose a recycled or locally sourced wood. Rift w Oak would be a good choice, tho species will make no difference in r-factor.  Stick with a typical frame and panel type construction, with some modifications.

   The first  thing to do is make the door thicker - 2-1/4 to 3" in thickness. This allows for insulated or even tripled glass units, sealed in place with integral wood stops on the exterior and loose stops to the interior. The thickness will also allow for thicker panels -2-1/4" is good, with a 1-1/4" or thicked tongue to go into the stiles/rails.  Raising will get then to the desired thickness.  Then the door can be rabbetted to firt into a double rabbetted solid jamb. This will provide two ledges for compressible weather-strips, similar (or exactly like) European doors. Use a wood sill since the metal sills will all be thermal holes. Bronze interlock (Pemko) is the best at the door botttom.

   Use architectural grade ballbearing hinges and source your hardware completely before building. The best door in the best house is no good if it is not properly fit and sealed - weather-stripped - to the elements.  A conventional latch will have to be adapted for the thicker door - the better manufacturers can do this, the cheaper ones cannot.  Consider a multipopint latch if the door has any size (8' tall or more than 36" width), tho English (conventional single point) will work for the door. Build a slight bow into the latch stile to compress the seals at the top and bottom and tension the latch.  Use solid wood for the jamb, cutting in the rabbetts and kerf for weather-strips.

   Since you are North facing (and hopefully under protection) the door can utilize a storm door.  This can also be sealed in place, tho can be considered redundant to a proper door.  A glass paneled storm door cannot be used if the sun hits the door, or it will become an efficient solar collector and destroy the door.

   Please do not consider plastic (fiberglass) or metal doors. Their claims to energy performance are marketing gimmicks at best, outright lies at worst. Thier performanc over time is far less than even a poorly made wood wood, and they are completely unrepairable - they must be thrown away - great for the environment.  There are some odd parts of the Leed code that I don't understand, but  wood doors should be mandated on every LEED house, if not all houses.  The problem is that accountants have been running the show at every BigDoorCo in the US, and all mass marketed doors are pure crap - wood, plastic, metal or otherwise.

   I always say one should consider hiring a professional for this type of work, especially the extra mile for the performance.  A door has to function, and function well, and everything comes together in a door - appearance, style, energy efficiency, security, safety, function and appeal - as well as craftsmanship.

   Dave Sochar

   Acorn Woodworks

5. 
   PSeverin | Jan 09, 2011 06:53pm | #5

   But is it significant?

     The answer to your question is that hardwoods have  an R-value per inch of 0.91 and soft woods 1.25.   Neither one is particularly good and simply going from 1 3/4" to something thicker will not significantly affect or do anything to the heat loss of the whole building.   It is a nice thought to do everything you can,  but moving away from the standard will just complicate hanging and getting a good seal on the door.  

   If you are really going for LEED certification, you have already spent and will continue to invest a considerable sum to get some bragging rights.   If energy use is your driving force,  give up LEED certification and investigate the German Passive Haus standards.   The Passive Haus standard can increase the cost of construction by 15 to 25 percent.

   My advise is to make a tight, well insulated house and make yourself a beautiful front door that is a pleasure to use and look at. Then make a beautiful storm door too.  

   Have fun

   Peter