A Prehung Exterior Door’S How-To?

In this video, carpenter and former senior editor Andy Engel demonstrates how to disassemble a prehung exterior door, measure and cut the door slab to fit an existing opening, and shorten the jamb to match. If you need a prehung exterior door that is shorter than normal, it is usually easiest to order it from the lumberyard. However, it is possible to shorten the unit yourself. Manufacturers typically allow wood doors to be shortened.

In most modern building contractors, door openings are made to standard sizes to accommodate prehung doors. If you own an older or custom home with a shorter than standard opening, you can reduce the cost by using a straightforward method focusing on water management, air infiltration, and smooth operation.

To upgrade a prehung exterior door, follow these steps: remove the old door, secure and weatherproof the door, and install the new one. Pull out the weatherstripping, keep it out of the way with a spring clamp, shorten it with a knife, and stuff it back into its kerf.

Prehung exterior doors cannot be cut down under any circumstances. They are manufactured as a complete weather-tight assembly. To install the new door, follow these steps: cut the bottom of the jamb/casing, flip the door assembly over, and finish with a handsaw. Open the door and use a rubber mallet or hammer to bend the steel under the door. Remove the head jamb, remove weather stripping, cut the sides to the size you need, put the jamb together, and weather the door.

On hollow core birch plywood doors, only two inches of wood at the top and bottom are needed. Steel doors cannot be cut but can be trimmed in place using a multi tool and a flush trim blade on a 3/4″ spacer placed on the floor.

Can you trim an exterior door?

Urethane foam frame molding is a lightweight, paintable, and easy-to-cut exterior door trim that is suitable for exteriors. It is available at local hardware stores or online. To install trim, measure the door and order the header at a specific length. Cut the casing to size. Protect the area with a drop cloth and remove existing exterior door trim using a flat pry bar, avoiding denting the siding or jambs. Use a scrap of wood as a fulcrum to ensure a secure fit.

Can you cut 2 inches off a door?

Trimming off a hollow core door can be done to accommodate thicker carpet, misread tape measure, or wonky doorframe. However, cutting off over 2 inches can cause the door’s edge to become non-solid. It’s not always advisable to trim hollow core doors for serious alterations. If unsure about trimming allowances, consult your supplier. If too much is cut off, the door’s structural integrity can be compromised, which can be fixed by reinserting a block from the bottom of the door inside the veneer using glue.

Can you make a prehung door shorter?

When ordering a shorter prehung exterior door, it is typically easiest to order from a lumberyard. However, it is possible to shorten the unit yourself, typically allowing wood doors to be trimmed by 1⁄2 in. at the top and 1-1⁄2 in. at the bottom. To do this, disassemble the unit, remove the door from its frame, place it on a surface that won’t scratch the door, and remove the door-bottom weatherstripping.

Mark the cut on each edge of the door and clamp a shooting board to the door, positioning the clamps with their long ends down to avoid interference with the saw. Place a block under each clamp to protect the other side of the door.

How many inches can you trim off a door?

Trimming hollow core doors can be done, but it’s not always advisable to do so unless serious alterations are needed. If you’re unsure about the amount of trimming, consult your supplier for trimming allowances. If too much is cut off, the door’s structural integrity can be compromised, which can be fixed by reinserting a block from the bottom of the door inside the veneer using glue.

How much can you trim off a door?

Internal door manufacturers typically recommend a trimming tolerance of 5mm per side, except for LPD which allows 3mm. If you need to trim a lot, you may have the wrong size and may be able to buy exactly what you need. If you need to trim to 6mm or 7mm, contact your chosen brand to determine if it’s okay. Trimming over a manufacturer’s tolerance will void warranties. The construction of the door, such as hollow core doors, also impacts the amount you can trim. Trimming too much may result in removing design features, as seen in the image. Therefore, it’s essential to consider the specifics of your door before attempting to trim it.

How to shave down a door without taking it off?

Sandpaper is a common method for shortening doors, especially when they are in situ. This method requires patience but is more accessible if you don’t have access to a planer. Hollow core doors can be planed, but a planer can be used for hollow core doors, but it’s important to avoid removing too much material. A hand planer can be used as long as even pressure is applied and the lipping isn’t removed more than the recommended amount. Both solid and hollow core doors can be planed.

How do you make a door that is too short fit?

To adjust the door and frame, first remove the door casing, top jamb, knob-side jamb, and inge side jamb using a pry bar. If the difference is less than one inch, furr out one side of the frame. If the difference is more than one inch, furr out both sides. If the issue is height, adjust the top jamb.

Using 2×4 lumber, cut appropriately sized furring strips along the width of the wood, allowing a gap of ½ an inch on either side of the door, and at the top and bottom. Attach the strips to the framing with wood screws that will bite into the framing by at least one inch. Drill pilot holes with a ¼ inch drill bit before inserting the screws to reduce the risk of splitting the wood.

Cut the jamb pieces to fit the new opening, ensuring the top jamb is shortened if the opening is narrowed, and the side jambs are slightly removed off the bottom if the opening is shortened. Attach the jamb pieces using new shims and level them with a level. Nail off the jambs with 2inch finish nails, placing them 10 inches apart.

Replace the casing and adjust the hinges if necessary. If the door is already hung and appears the right size but is sticking, it could be due to sagging or loose hinges.

What to do if door frame is too small?

To adjust the door and frame, first remove the door casing, top jamb, knob-side jamb, and inge side jamb using a pry bar. If the difference is less than one inch, furr out one side of the frame. If the difference is more than one inch, furr out both sides. If the issue is height, adjust the top jamb.

Using 2×4 lumber, cut appropriately sized furring strips along the width of the wood, allowing a gap of ½ an inch on either side of the door, and at the top and bottom. Attach the strips to the framing with wood screws that will bite into the framing by at least one inch. Drill pilot holes with a ¼ inch drill bit before inserting the screws to reduce the risk of splitting the wood.

Cut the jamb pieces to fit the new opening, ensuring the top jamb is shortened if the opening is narrowed, and the side jambs are slightly removed off the bottom if the opening is shortened. Attach the jamb pieces using new shims and level them with a level. Nail off the jambs with 2inch finish nails, placing them 10 inches apart.

Replace the casing and adjust the hinges if necessary. If the door is already hung and appears the right size but is sticking, it could be due to sagging or loose hinges.

What to do when doors are too short?

In order to disguise the door, a strip of wood should be cut and affixed to the bottom of the door, after which it should be painted. As an alternative, one might consider the purchase of a taller door slab or the affixing of a piece of wood to the bottom of the door and subsequent painting.

How do you fix an exterior door that is too short?

It is necessary to drill four pilot holes through the door’s bottom, ensuring that both the filler piece and the door are penetrated. The next step is to countersink the holes using a countersink bit. Subsequently, wooden screws should be inserted, with the heads countersunk below the door’s bottom surface, thus reinforcing the joint.