Replacing an Old Intercom with a Ring or Nest Doorbell: Complete Guide

Replacing an old intercom with a video doorbell is one of the most satisfying home upgrades you can make — but it's rarely as simple as "unscrew old thing, screw in new thing." Old intercoms are big, weirdly positioned, mounted horizontally while your new doorbell is vertical, and leave holes that don't match any standard mounting pattern.

We handle these conversations every single day. Here's the complete playbook.

Both of these customers got exactly the right custom plate made to their measurements. This guide explains how to get there yourself.

Step 1: Remove the Old Intercom and Assess the Damage

Before you measure anything, the old intercom has to come off. This reveals two things you need to see: the actual hole in the wall, and the screw holes that held the old intercom in place. Those existing screw holes become your new attachment points — you'll use them to mount the cover plate, which means no new drilling into the wall.

1. 1
   Turn off power at the breaker

   Even if your intercom looks dead, turn off the circuit breaker for any doorbell or intercom wiring before touching anything. Low-voltage systems won't kill you but can still spark and damage your new doorbell.

2. 2
   Remove the intercom faceplate first, then the housing

   Most intercoms have a faceplate that pops off or unscrews, revealing a deeper housing or box in the wall. Remove both layers — you may find the actual wall opening is significantly larger than what the faceplate showed.

3. 3
   Check for a mounting ring or raised bracket

   Many vintage Nutone and M&S intercoms sit on a raised mounting ring that protrudes from the wall. If present, remove it — the ring is not part of the wall. The actual screw holes underneath may have different spacing than the ring did.

4. 4
   Leave the wires accessible

   Don't cut or tuck the intercom wires yet. You'll need them to power your new doorbell. If there are more wires than you expect (some intercoms have 4–6 wires), photograph them and their colors before disconnecting anything.

Step 2: Measure the Hole — Three Dimensions

With the intercom completely removed, you need three measurements. Take your time here — this is the most important step. Inaccurate measurements are the only thing that causes a cover plate not to fit, and you're responsible for providing them correctly.

Step 3: Pick Your Cover Plate Size

The cover plate needs to be large enough to fully cover the old intercom hole plus any wall damage or marks around it — with enough overlap on all sides that it looks intentional, not patched.

How to determine the right plate size

Add at least 2 inches to each dimension of the hole (1" overlap on each side). If there's visible wall damage or old paint lines beyond the hole, go bigger. Common plate sizes we make:

Step 4: The Horizontal-to-Vertical Conversion

Here's the situation that comes up constantly: old intercom was mounted horizontally on a side wall. New doorbell is a vertical device. You need to convert the orientation completely — and also get the camera facing the right direction.

The customer from April 2025 solved this with a 6.5" × 6.5" silver square plate with 5-5/16" horizontal hole spacing, a center wire hole, and a 0–35° swivel adapter to aim the Nest Gen3 camera toward the approach path. The square shape was intentional — it looks balanced around a vertical doorbell in a way that a rectangular plate would not.

Step 5: Handle the Wiring

Most intercom systems use low-voltage wiring — the same type as standard doorbell wiring. Here's how the wiring situation varies by your new doorbell type:

Step 6: Add an Angle Adapter (If Needed)

If the intercom was on a side wall — which it usually is — your cover plate will be flush to that side wall, but the camera needs to face toward the front door or approach path. This requires an angle adapter on the face of the cover plate.

The cover plate mounts flush to the side wall using the old intercom holes. Without an angle adapter, the new doorbell's camera would face whatever is directly in front of that wall — often the yard, the street, or a fence rather than the approach path to your door. The angle adapter sits between the cover plate and the doorbell, rotating the camera to face the right direction.

We pre-drill the cover plate for whichever swivel base you need. Just let us know when ordering — or text us a photo of the wall layout and we'll recommend the right angle range.

Which angle adapter do you need?

• Subtle correction (0–35°): Intercom was close to the front corner of the wall, camera only needs a small turn. Order a cover plate pre-drilled for the 0–35° swivel base, and we'll include that swivel mount.
• Major side-wall turn (15–90°): Intercom was fully on the side wall, camera needs to make a 45–90° turn to see the front. Order a cover plate pre-drilled for the 15–90° swivel base. This was the right call for the April 2025 customer above.
• Not sure: Tell us where the intercom was relative to the door and text a photo — we'll recommend the right angle.

Common Intercom Brands & Their Screw Spacings

If you recognize your old intercom brand, this gives you a starting point for the screw spacing — but always verify by measuring, since installations vary.

How to Order Your Custom Plate from DoorbellMount.com

1. 1
   Go to the intercom cover plate listing

   Visit doorbellmount.com/products/intercom or browse the intercom covers collection for standard sizes. If your size isn't listed, use the custom made-to-order listing.

2. 2
   Provide your three measurements in the order notes

   Hole height × width, screw hole center-to-center spacing, and whether the screw holes are vertical or horizontal. Include your new doorbell model so we drill the right front-face holes.

3. 3
   Specify angle adapter if needed

   Note if you need the plate pre-drilled for a 0–35° or 15–90° swivel mount base — we'll include the swivel in your order or adjust the holes accordingly.

4. 4
   Select your color

   Default is black. Request white, silver/grey, brown, or other colors via the Color Change Request add-on. Silver is common for older intercom locations where the existing surround was metal.

5. 5
   Or just text us photos

   Text photos of the old intercom hole, a tape measure showing the measurements, and your new doorbell to 833-326-6868. We can often quote and confirm the right plate in one conversation before you order.

Products you may need for an intercom replacement

Frequently Asked Questions

Can I reuse the old intercom's screw holes for the new cover plate?

Yes — that's exactly the plan. We drill the cover plate's wall-mounting holes to match your old intercom's screw spacing, so the plate anchors to the existing holes without any new drilling. You provide the spacing measurement; we handle the rest.

What if my old intercom had 4 or 6 screw holes?

Use the 2 holes that give you the most stable mounting — usually the outermost pair with the widest spacing. Note the measurement of those 2 holes specifically when ordering. The other holes can be left empty behind the plate.

My intercom was on a gang box — does that change anything?

Standard single-gang boxes have 3.281" (3-9/32") vertical screw spacing. We have a gang box adapter plate specifically for this situation, or we can custom-drill any cover plate to that spacing.

The old intercom was recessed several inches into the wall — what do I do?

If the old intercom box is deeply recessed, you have two options: (1) install a standard weatherproof gang box into the recess as a new mounting surface, then mount the plate over that, or (2) order a custom plate with a raised/extended neck that bridges the depth. Text us photos and we'll advise the best approach for your situation.

How long does a custom plate take to ship?

Most custom intercom plates are printed and shipped within 1 business day. We 3D print them from PETG — a durable, weather-resistant material — and they're ready for exterior use immediately.

What if my measurements were slightly off?

We offer a fit guarantee — if the plate doesn't cover your opening based on the measurements you provided, we'll work with you to send a corrected replacement. Accuracy is your responsibility, but we're not going to leave you stuck if something's off by a small amount.

Published by DoorbellMount.com  ·  Written by Ricky, Mechanical Engineer & Founder, Louisiana  ·  Updated 2025