I need help with an exterior door

I want to replace the exterior door of my sunroom.

Because its a sunroom the walls are not nearly as thick as a typical wall and the framing is metal, so pre-hung doors with wood frames don't help me.

I want to just get a new door and hang it myself. If this had normal framing I know how to remove trim and get the rough in opening and install a pre-hung door, but in this case I just want to replace the door and not any of the jamb or door frame.

The existing door measures 34 5/8" wide by 78 7/16" high. The opening is something like 35 1/8" wide by 78 7/8" high.

These do not seem to match up with standard door sizes unless doors are measured like dimensional numbers where the listed size is not really the actual size.

Looking for a left hand in swing fiberglass door that is mostly a window except I want a doggie door in the lower portion. If that means buying a half lite door and installing the doggie door myself that is ok too. I just need to know what size door I need.

Help me learn about door dimensions..

In reply to T.J. :

That door was part of the system with the sunroom. 

You cant buy a fiberglass door that size, unless its custom, and a custom door would be grossly expensive. 

Find the manufacturer of the sunroom, and talk with them about doors available with their system. 

... sunroom doors are frequently undersized in height so that a door can fit in an exterior wall, and the roof above it can still have pitch back to the house while being able to tuck under the existing eave. 

That is what I was afraid of. I have no idea who made the sunroom. The original owner had it installed I think sometime after new construction.

The door itself.was made by Premdor. It is called a Castlegate if that helps.

I just was thinking fiberglass so it won't rust like the steel door has. Too much salt in the air.

I mostly just want something not rusty that I can install a doggie door in that has as large of a window as possible and it opens and closes and it keeps water out.  Maybe I'll have to buy a wood door and trim it to fit or just try to make a door. I don't want to spend the money for a custom sized one off.

The other option that might work is to just get a storm door and mount it outside and remove the actual door. Just looking for something to keep rain and bugs out does not have to insulate or provide security.

I'll take a look around in the sunroom and see if I can find any type of label as to who manufactured it, but I've not been able to find anything in previous searches.

Try to see if they pulled a permit when they built the sunroom. Might have information on the permit to get you to the right people. 

Not sure how much security you want but my neighbor about 10 years ago made his own porch door as it was an odd size as well. He used painting frame parts from his cousin's art store. He didn't want to figure out the corners and the frame wood has some pretty finish details in it. Mostly he might have got all of it for cost or family free discount.

Still a viable path to take. Nowadays you can find pre cut angles for door/window frames to inset hardwood, plywood or whatever core you want for the door. Or you can disassemble a Big Box store door and cut it down to size as needed. 

Yeah, I could make something out of wood. Would rather have fiberglass so I won't have to worry as much about maintaining it.

Buying a wood door a little larger than I need and cutting it down may be the easy route. I'll stop by the habitat for humanity restore to see what they have in stock for old doors. I need some glass and that could be a good starting point.

If I read the clues correctly, the PO had the sunroom built on an existing deck and added the roof over it when he had the shingles replaced with a steel roof. I think I have something from him that says what year the roof went on. I'm relatively sure they pulled a permit for it, but who knows.

My old sunroom had just a storm door and it worked out well. We didn’t have a pet door in that particular storm door but one of our other storm doors did and it was fine. A good storm door still isn’t as secure as a regular solid door but with all that glass nothing will be. The better quality storm doors have actual key cylinder locks and can be keyed to match your house doors. I think ours with that feature was an Anderson aluminum door. 

Check with mobile home suppliers, and RV suppliers. 

You might get lucky. 

Post pictures of some of the details of the room, I might be able to identify manufacturer from the extrusions 

What I have learned about hanging doors is that I cannot get them plumb, straight, square or level.  They are the bane of my existence.  

I'll echo the RV and mobile home supply ideas; specifically your sunroom's manufacturer.  Chances are they had several door options and likely had a door manufacturer who makes their custom size in bulk.  Cheaper than having someone custom build your size

That is just not a standard door size.  Doors are almost always 80" or 84" high, and widths usually go in 2" increments from 24 to 36"  Usually the slab itself is what is used for the nominal designation.  So a 32" door has a 32 (or sometimes 31-7/8") slab and then add 1.5" or so for the frame and gap for a rough opening of 34 ish.

I would give a shot with HD or Lowes.  HD's software is much nicer and I found their pricing to be a bit better.  They stock the normal sizes, but they have several suppliers who can make a custom door size with custom jambs.  It won't be cheap, but it might not be as expensive as you think.  The nice thing is, HD's software lets you input the rough opening size OR the door size.  Let them walk through the process and they can give you a price.

The other option (and what I do freqently at the theater) is to customize the opening to fit a cheap door.  A pre-hung door isn't that much easier in my opinion.  So if you were to remove the door, you're saying you have 35-1/8" between?  I would consider getting a single piece of 1x4 PT or Trex (3/4" actual thickness) to shrink the opening and then buying a 34 x 80 door to put in there by cutting 2" off the bottom and replacing the bottom with a weatherstrip/sweep.

The one time I had to deal with that, probably ten years ago, I ordered a custom storm door.  I don't recall the price which makes me think that it was pretty reasonable.

In reply to Patrick :

Here are some pics. The house was built in 1991 or so. Not sure when the sunroom was added.

In reply to Curtis, SVreXx and dculberson :

Thanks for the suggestions. I think I looked at both Lowes and Home Depot websites last fall for doors. The easy button may just be a storm door, but the only times I've installed them it was on regular doors with wood casings, Not sure what exactly is behind the metal extrusions that I would be drilling holes into.

I'll take a closer look at narrowing the opening so a standard 34" wide door could be used.

Most of the sunrooms I've dealt with, those vertical aluminum pieces are I-beams.  The fiber panels slide into the channels.

I personally wouldn't hesitate to take the door frame out and frame in whatever I needed.  Last one I did I took the extruded piece off the I-beam (I had to drill a lot of rivets).  then I took a PT 2x4 and ripped it down to about 2-7/8" so it fit in the I-beam and attached it to the I-beam with self-tappers and liquid nails (which was overkill, but I figured it would double as an air seal and prevent drafts).  That gained me an inch.

Long story short, its up to you.  The support comes from the aluminum I-beams so you kinda can't screw it up.  Its not like you'll damage structural integrity by stripping out the door frame.

So, I know what I will be doing this weekend. I'll take it a part and see what I have to work with. There is a little over 36" between the inside edges of the two vertical I-beam extrusions. There is something around a 1/2" of reveal for the door frame on either side.I'll take it a part and see how much room there is in the web of the I-beam extrusions. Maybe I can get a 36" door in there.

There is no room to really expand on the non-hinge side as there is a structural post on that side, but there is about 6" on the hinge side to the corner of the house. There is an I-bream going up at the corner and then maybe 3" of exposed panel, then the I-beam for the door. I may be able to take a couple inches here, but there is a transom window over the door that would then not line up with the door.

Once I get it opened up I'll hopefully know which way to go.

Home Depot has this on their site that other than being too narrow is close. They have wider versions, but only as pre-hung units. Looks like buying a pre-hung adds a couple hundred to the price, but I bet I can special order what I need.

I think I could make a standard 36" x 80" door fit if I relocate the hinge side I-beam a bit. I think I can come up with something to make the transom window still work and be weather tight.

Thanks for the help.

They do make a door frame extrusion  that attaches to the i beams and is 4 9/16 deep witha lip inside for a standard door frame to butt to, but aside of places up here I couldn’t tell you where to find it.  I could order some and ship it to you but otherwise you’re looking to build something or reconfigure.  I don’t recognize those wall panels, must br a southern manufacturer.  All the ones up north use panels that are textured differently than yours, and they all use hex head screws.  You could get a 34” door to minimize width difference to transom glass.  These rooms are like legos, it’s not going to be hard to move things around some

So , I took the existing door off and then removed the entire wall it was in. I am confident I can make something work, so I ordered a 36"x80" door with pet door. It will take about a month according to Home Depot. Then I put everything back together. 

So, I picked up the new door last Sunday. Took the wall down again and then figured out a way to make a rough opening framed out with 2x4's and still retain the aluminum channels so I could still use the window above the door. All that is left is to trim off the excess expanding foam on the inside and install some trim pieces. Oh, and also to train the dog to use the doggie door.

Thanks for all the help and suggestions in this thread.