Doors
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How to Fix a Warped Exterior Door

Exterior doors are one of the most used features of a structure. Exterior doors must endure temperature differences from one side to the other that can exceed eighty degrees or more. In addition, these doors must tolerate wind, rain, and snow while maintaining an airtight seal against the door frame. With all of this abuse, exterior doors occasionally need to be adjusted for optimal performance. Today, we will discuss a few common ways to correct a warped exterior door and/or frame.


Why Does My Exterior Door Leak Air?

There are a number of reasons why an exterior door might leak air, including problems with the hinges, settling of the door frame, and moisture. Here we will describe the most common exterior door issues that might cause the door to drag, not latch, and leak air. 

In the vast majority of situations, an exterior door that no longer seals against the door frame has loosened its grip on the hinges. Loose hinges are very common because every time the door is opened or closed the hinges (and the screws holding it) wear just a little. Most often, this involves the top hinge on the door because the forces acting on the door are strongest at the top latch side of the frame.

Solving this issue is quite easy, as in most cases a screwdriver is all that is needed to correct the problem. However, in some situations, this repair has been made before, so the hole in the frame no longer holds the screw tightly. When this occurs, the pros will simply use a longer screw. Using a longer screw the same diameter as the original allows the screw to contact new wood and cut new threads. In most situations, using a coarse thread wood screw at least 2” long will allow the screw to pass through the door frame and into the rough opening.

Another common exterior door malady is a warped or sagging door frame. In most cases, this occurs with age or inadequate support within the foundation, such as sagging floor joists or trusses. In most structures, exterior doors are made from wood surrounded by steel, solid wood, or wood surrounded by fiberglass. The door frames, however, are typically made completely from wood, which makes them more easily adjusted.

For steel doors, this usually involves removing any door casing or brick molding installed on the door to allow access to the door frame. In this example, we will assume the door is dragging and will not latch.


How to Repair a Sagging Door Frame

Here we will describe the process of squaring up a sagging door frame.

Step: 1 Locate the Problem

The first step is to locate the area that is dragging. Often, this can be located easily because the paint on the edge of the door will be missing where it is dragging. The most common locations for a dragging door are on the top corner and the bottom of the latch side, but it can occur anywhere.

Step 2: Move and Secure the Door Frame

Professionals will usually start with the door completely open and using a hammer and block of scrap wood, tap on the frame until it starts to move. Movement will indicate that there is space within the rough opening to move the door frame. In many cases, an adjustment of just a millimeter or two is needed. The important part of this step is to make sure the door opens and closes freely. Once this is confirmed, the frame is pre-drilled, and 2” wood screws are installed through the frame into the rough opening to avoid future movement.

Today's Homeowner Tips

The pros will often use the door itself to test the opening instead of using a carpenter’s square or speed square. The pros do this because the door itself may not be square, so squaring the door frame might actually make the problem worse.


How Do I Flatten a Warped Wooden Exterior Door?

Correcting a warped door can be quite involved, so depending on the severity of the damage replacing the door might be more economically feasible. However, here we will describe the process of straightening an exterior door when the warpage is relatively small. Unless the door is very elaborate and very difficult to replace, many professionals will only attempt the repair if the door is warped by no more than ¼”.

Steel Exterior Door

There are a couple of ways to try and flatten an exterior door, depending on the type of door. Steel doors tend to come apart around the edges where the steel meets the wood frame because sometimes the steel skin gets pulled away from the frame if the door gets drags. In many cases, if the steel skin is just bent, the pros will use a caulk gun and construction adhesive to rejoin the steel to the frame. The door is then clamped together and allowed to dry before testing.

If the door still drags, chances are good that the steel skin is dragging on the threshold of the door frame. To correct this, most steel exterior door manufacturers include brass adjustment screws. As an example, if the door is dragging on the latch side bottom, a couple of counter-clockwise turns of the screw closest to the drag will lower the threshold by about ⅛”. Additional adjustments can be made to each screw in the threshold until the problem is resolved.

Wooden Door

Option 1: Bend the Door

Wood exterior doors tend to warp more than other door types, but they are usually also the easiest to correct. Wood doors typically do not have the separation problem that steel doors encounter, but rather the actual warping of the slab. Wood exterior doors are often made from hardwoods, such as farm-raised mahogany and poplar, or naturally rot-resistant woods like redwood and cedar. Correcting warps in wood doors will usually involve moisture, sanding, or both.

Warps in wood doors are often the result of inadequate finishes that allow outdoor moisture to contact the wood. Other times, the door does not contain additional bracing such as lap joints at the corners, which allows the door to naturally warp in the direction of the grain. Either situation can often be corrected if the problem is resolved early. Unfortunately, both methods will usually require removing the finish. 

The first method involves removing the finish from the edge of the door. In most cases, this will be some form of varnish or polyurethane and can be done with sanding or varnish remover. Next, the door is clamped onto a very flat surface, and water is applied sparingly to the raw wood frame exposed by the sanding. The door is then allowed to dry completely and re-hung to test the operation. If the door tries to spring back to its original position, the process can be repeated, but water must be used sparingly to avoid raising the grain.

Option 2: Sand the Door

Probably the most common solution to flattening a warped wood door is sanding. However, sanding should be done in small increments because power sanders remove material very quickly. In fact, if the dragging is minimal, most professionals will remove material by hand to prevent accidental over-sanding.

If the door is warped on the latch side, usually the best method combines hinge adjustments as well. In many cases, this method will correct the problem without removing too much of the door. If possible, the pros will often perform this without removing the door from the hinges, as it allows them to test every change as it occurs. Once the shape of the door has been corrected, the pros will sand just a little bit more off to allow for the addition of the new finish. 


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