How to Install a Pet Door in a Screen Door or Lanai

Complete DIY Guide to Screen Door, Lanai, and Screen Enclosure Pet Door Installation
Step by step instructions for the Security Boss Pet Screen Door and the SB4 Pet Screen Door, including how a lanai gets framed for a solid install.

⏱️ Estimated Time: 30 Minutes to 3 Hours | 🔧 Difficulty: Moderate | 👤 People Needed: 1 to 2

Option 1

Security Boss Pet Screen Door

Drops into the bottom corner of a screen door panel you already have.

• Sliding and swinging screen doors
• No framing required
• 30 to 60 minutes

See the install steps

OR

Option 2

SB4 Pet Screen Door

Sits in a framed opening we build into your enclosure.

• Lanais, screen enclosures, porches, storm doors
• Framing required on all four sides
• 2 to 3 hours with framing

See the install steps

Not sure which one you need? The comparison table below breaks it down, or call 855-DOG-DOOR and we will tell you in about a minute.

Before You Begin

Adding a pet door to a screen is one of the quickest pet door projects there is, but the right product depends entirely on what you are cutting into. A sliding screen door panel and a screened lanai are two very different structures, and they take two different doors.

This guide covers both. The Security Boss Pet Screen Door drops into the bottom corner of an existing sliding or swinging screen door panel. The SB4 Pet Screen Door is a heavier unit built for lanais, screen enclosures, screened porches, and storm doors, and it needs a framed opening on all four sides.

📋 Things to Consider Before Installation

• What you are installing into: A screen door panel, a lanai or screen enclosure bay, a screened porch, or a storm door. This single question decides which product you need.
• Screen Door Type: Screen doors come in three main types: hinged screen doors (standard swing open), sliding screen doors (for patio and slider tracks), and retractable screen doors (roll up). Pet doors work with hinged and sliding types. Retractable screens are not compatible with pet door installation.
• Frame Material: Aluminum frames are the most common and easiest to work with. Vinyl and wood frames are also straightforward. Heavy gauge steel frames may require special drill bits.
• Screen Material: Standard fiberglass screen, aluminum screen, pet resistant screen, and solar screen all work fine. The screen inside the pet door opening gets removed.
• Structure Strength: A standard lightweight screen door may flex or sag with a pet door installed, especially with a larger dog. Screen enclosure panels have no rigidity at all on their own, which is exactly why the SB4 gets framed in.
• Pet Size: Both doors are available in sizes from cats through large dogs. Measure your pet before you order anything.
• Dual Door Setup: A screen door pet door only works when your primary exterior door is left open. If the main door is closed, your pet cannot get through.
• Bug Protection: Both models use brush weather stripping and magnets to pull the door shut behind your pet, which keeps insects out when it is not in use.
• Reversibility: Removing either door later means re screening the panel or replacing it. This is not as easily reversible as a window or patio panel insert.

Which Door Do You Need?

🛒 Compare both doors in our screen pet door collection

For sliding and swinging screen door panels

🔧 Tools & Materials

Step 1: Size the Door to Your Pet

• Width: Measure the widest part of your pet at the chest and shoulders, then add roughly 2 inches for clearance.
• Height: Measure from the floor to the top of your pet's shoulders at the withers.
• Step over: This door mounts into the bottom corner of the screen panel, so the bottom of the opening sits at the height of your screen door's bottom rail. Confirm that is a comfortable step over for your pet.

Step 2: Remove the Screen Door Panel

Most sliding screen doors ride on rollers with tension screws near them. Loosen those screws and the panel lifts out of the track. Some brands, including Pella, hang the panel from rollers at the top. Loosen the screws along the interior top edge and the door drops far enough to clear the floor channel. Lay the panel flat on a work surface such as a pair of sawhorses or a clean patio table. Working flat is not optional here. You need even tension on the screen when you spline it back in.

Step 3: Position the Pet Door and Mark Your Cut

1. Set the pet door on the panel with the spline grooves facing up. It must sit in a bottom corner.
2. Match the orientation to your existing door. Most patio screen doors have the screen spline groove on the exterior side, so the pet door spline groove should face the exterior as well.
3. Mark the horizontal cut line on the screen. Set that mark about 1/8 inch in from the end of the H channel overlay flange so there is enough screen left to roll into the pet door spline groove. Call this Point A.
4. Make the same 1/8 inch mark at the bottom corner of the overlay flange. Call this Point B.
5. Draw a straight line inward from Point A and upward from Point B. Where they meet is Point C.

Step 4: Cut the Screen

1. Using a straight edge and utility knife, cut from Point A to Point C.
2. Cut from Point C to Point B. A builder square helps keep this square and clean.
3. Cut along the inside edge of the screen door frame to release the section. Do not pull the screen away from the spline and do not remove the spline.
4. Lift the cut section away.

Step 5: Fasten the Pet Door

1. Position the pet door over the cut opening and seat it firmly into the corner of the screen door frame.
2. Using the included bit, drill roughly 1 inch in from the ends of the overlapping flange.
3. Secure with the provided low profile screws. Do not drill all the way through the screen door frame.

Step 6: Spline the Screen Back In

1. Using the roller tool and rubber spline, start at Point A and roll the screen into the pet door frame moving toward Point C.
2. Repeat from Point C to Point B.
3. Keep constant pulling pressure on the screen as you roll so it finishes tight with no sag or ripple.
4. Trim any excess screen with the razor blade.
5. Rehang the panel in the track and confirm it still rolls, closes, and latches correctly.

For lanais, screen enclosures, screened porches, framed screen doors, and storm doors

Why the SB4 Needs Framing

The SB4 is not a corner mount door. It is built around a rough opening and needs solid material on all four sides to fasten to and to hold its shape. A screen enclosure panel is just screen splined into aluminum extrusions, so there is nothing in the middle of a bay for the door to grab. That is where framing comes in. We add horizontal and vertical structural lanai extrusions inside the existing bay to build a proper opening for the door. The result is a pet door that stays square, does not flex when a large dog pushes through it, and does not pull on the surrounding screen. In the photo you can see the finished result. The door sits in its own framed opening with new members above and to the sides, and the screen is splined back in tight around it.

🔧 Tools & Materials

Step 1: Size the Door to Your Pet

• Size the door so the pivot point sits about 2 inches higher than your pet's shoulders. That is the measurement Security Boss builds around and it keeps the door comfortable long term.
• The resulting bottom of the opening should be a comfortable step over height for your pet.
• Measure the widest point of your pet at the chest to confirm the width you need.

Step 2: Pick the Location in the Lanai

1. Choose a bay near where your pet naturally travels, usually next to the door you already use to let them out.
2. Never cut into or modify the structural uprights and beams that carry the roof or cage load. The framing we add goes inside a screen bay, not through the structure.
3. If you ordered the blocking panel option, the panel lifts out vertically. Make sure there is clear headroom above the door to pull it out.
4. Watch for the kickplate at the bottom of many enclosures. It often sets your minimum height and sometimes gives you a solid bottom side to frame against.

Step 3: Determine Your Rough Opening Size

Frame to the dimensions below. These are exact, so add slightly depending on how clean your cuts come out.

Step 4: Frame the Opening

This is the part that makes or breaks the install. Take your time and keep everything square.

1. Cut the spline and remove the screen from the bay you are working in. Save the spline size so you can match it when you re screen.
2. Measure and mark the rough opening on the existing uprights. Work off the finished floor for your height mark, not off the screen, which can stretch.
3. Cut two horizontal extrusion members to span between the uprights, one for the head of the opening and one for the sill.
4. Fasten those into the existing vertical uprights with self tapping screws. Check level on both before you drive the second screw in each.
5. Cut and install vertical extrusion members between the new head and sill to close in the left and right sides of the opening.
6. Measure both diagonals of the finished opening. If they match, the opening is square. If they do not, loosen and adjust before you go further.
7. Confirm the total framing thickness is 2 inches or less from the interior face to the exterior face.
8. Re screen the bay around your new framing, splining the screen into the extrusion channels and keeping constant tension so it finishes tight.

Step 5: Install the SB4

1. Separate the interior and exterior door frames.
2. Set the inner frame into the rough opening from the inside.
3. Snap the outer frame into place from the outside and sleeve the two halves of the pet door frame together.
4. Using the pre drilled pilot holes and the supplied 7/64 inch bit, drill and insert one screw.
5. Check level. When the door reads level, tighten that first screw down.
6. Drive the remaining screws using the pilot holes as guides. Work opposite corners rather than going around in a circle.
7. Fill any gaps and seal the edges with exterior grade caulk if desired.

Step 6: Test and Train Your Pet

1. Swing the door by hand several times. It should move smoothly on the pivot and pull itself closed on the magnets.
2. If you have the blocking panel, lift it out and drop it back in to confirm clearance.
3. Encourage your pet through with treats. Hold the door open at first so they can see the opening clearly.
4. Most pets pick this up in a single session because the swing action is light and there is no flap resistance.

💡 Tips & Tricks

• Order the door first, then frame to it: Every SB4 is hand built to order. Frame your opening after the door arrives so you can verify against the actual unit instead of a chart.
• Use an existing upright when you can: Positioning the opening against an existing vertical member means one less piece of extrusion to cut and a stiffer result.
• Check your diagonals: On a framed opening, equal diagonals is the only real test of square. A level tells you nothing about racking.
• Upgrade to a heavy duty screen door: For a medium or large dog on a standard screen panel, a flimsy door will eventually sag. A heavy duty screen door with reinforced corners holds up far better.
• Install pet resistant screen while you are in there: You already have the spline out. The SB4 and the Security Boss Pet Screen Door both use pet scratch resistant screen in the swing panel, so matching the surrounding bay makes sense.
• High wind locations: If your lanai catches heavy coastal wind, Security Boss offers upgraded neodymium magnets for a stronger closure.
• Seasonal use: Screen pet doors are ideal spring through fall when you want the main door open for ventilation.

⚠️ Common Mistakes to Avoid

• Trying to install an SB4 without framing: It cannot fasten to screen. Without four solid sides the frame will not stay square and the door will sag out of the opening.
• Framing thicker than 2 inches: The two frame halves sleeve together through the opening. Build past 2 inches and they will not meet.
• Removing the spline on a screen door install: On the Security Boss corner mount, cut the screen but leave the existing spline in place. Pulling it out means re splining the entire panel.
• Cutting too close on the screen door model: Leave the 1/8 inch of screen material past the H channel. Cut it flush and you have nothing left to roll into the spline groove.
• Drilling all the way through the screen door frame: The included screws are low profile for a reason. Going through the back of the extrusion weakens it.
• Cutting a structural upright in a lanai: Those carry load. Frame inside the bay, never through the cage structure.
• Installing on a retractable screen: Retractable roll up screens cannot support a pet door. The screen retracts into a cassette and the added rigidity will jam the mechanism.
• Forgetting the main door is closed: A screen pet door only works when your primary exterior door is open.

When to Call a Professional

The corner mount screen door install is very DIY friendly. The SB4 is a different story. Consider professional help if:

• You are installing into a lanai or screen enclosure and need the opening framed
• You do not have a way to cut aluminum extrusion cleanly and square
• Your enclosure is under warranty and you do not want to risk voiding it
• Your screen door is custom built or has an unusual frame configuration
• The screen door is part of a multi panel or French screen door system
• You want the enclosure re screened with pet resistant material at the same time

Portal Pros installs screen door and lanai pet doors nationwide.
📞 Call 855-DOG-DOOR for a free estimate.

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