Here’s my second article in a sort of “exterior door installation” series. You can see my article on “How To Stain And Finish A Wood Door” for pictures and description of the work I did on the bare door of this project before preparing the doorway.

Before you begin removing an old door, you should have everything you need for the new installation ready to go including the new door, and you need to be sure all the new door dimensions will work in the rough opening. Manufactured doors come in standard widths of 30″, 32″ and 36″. 80″ high and 1-3/4″ door thickness is typical. The jamb width is usually 4-9/16″ or 5-9/16″. Other sizes than typical ones I just stated are also available. but the point here is to make sure you do not have to stop in the middle of a project to go get needed materials.

Remove the interior trim, the exterior trim and the threshold. Take mental note of the placement of shims that supported the old casing. If there’s insulation, remove that as well.

There should be if there’s not any, so you’ll need some for the new door. A hammer and crowbar are what I use for removing the old casing. Once the existing door is removed, the rough opening needs to be cleaned well. The key to a successful installation is the preparation of the bottom of the existing opening. If your rough opening threshold is bowed, crooked or bumpy, you’ll need to straighten it up and get it as square as possible to plumb. That just means it needs to be nice and flat and level to the ground or structure it’s going into and be very solid.

There are several methods used for truing up the bottom of the rough opening. If the existing base of the opening is concrete, you could add concrete to it to level it out, but it is likely that the overlay of concrete will crack and crumble.

Probably sooner rather than later too. I have heard of shimming and filling with expanding foam, but I can’t see that as particularly trustworthy. I have never tested the method myself, so I cannot say for sure. Mostly, I’ve been lucky enough to have only installed doors in nearly square doorways. A good concrete leveler seems to be the right answer to this dilemma, but it is impractical to use in a doorway since it needs to be poured. Perhaps some shoring may work with a good leveler. This handyman hasn’t tried it.

What I have done is run some shims under the threshold until I get it level, then remove the threshold. I use liquid nails generously (possibly over half a tube) along the path of the threshold then re-install it over the shims. The liquid nails takes about 48 hours to dry, but once it dries, it is very hard, waterproof and holds everything together.

At one property, I put in a threshold and had to remove it three years later after the owner decided to replace the entire door. It took a lot of time and serious effort to remove that piece of wood! It is my preferred method and it has worked for me over the years.

Once the base of the doorway is clean and level, you should also clean all the way around the rough opening and make sure the exposed studs are clean and solid. Check everything with a square and level so you can get a good idea where your shims will need to go. You don’t need to take a memory course or anything like that , but getting a strong sense of how the old door went in will help you out later on.

With the old door removal complete, the base of the threshold in, and everything cleaned up, you should be ready to install a new door.

I didn’t really write about painting the jamb, but you can see part of it in the third picture to the right. I chose a satin exterior latex enamel that complimented the natural colors of the wood door and painted it during the same period I stained and finished the door.

In my next article I’ll cover installation basics and some useful door installation tips.