A door threshold is the raised strip or sill where two floor surfaces meet in a doorway — timber to tile, or the track of a sliding door. For a robot vacuum it is a climb: each model is rated for a maximum threshold height, so the sill’s height decides which models can cross it into the next room.
In short: it’s the little step in your doorway, and its height is what you check against a robot vacuum’s threshold rating.
How Thresholds Affect a Robot Vacuum
Every robot vacuum model is rated for a maximum threshold height, and the height of your sill decides what happens at each doorway:
- Below the model’s rating. The robot crosses and carries on cleaning the next room in the same run.
- Above the model’s rating. The sill stays on the map as a boundary. The robot cleans up to it and treats the doorway as an edge, so the room beyond needs another way in or a model rated for that height.
- How it crosses depends on the model. Some models use a liftable chassis that raises the body or individual wheels to climb taller steps. On the Saros 20, the product page describes the AdaptiLift™ Chassis 3.0 as an advanced vision system, adaptive algorithms and a main wheel + auxiliary wheel + climbing arm lifting structure that let the robot analyse, test and memorise the best way to cross a threshold. Models without a liftable chassis are rated for lower thresholds; the figure is on each model’s product page.
When Does Threshold Height Matter?
Most homes have at least a few transitions between rooms or floor types, so threshold height is worth a quick check for anyone buying a robot vacuum. It matters most if:
- You have a sliding door track the robot needs to cross to reach a sunroom, deck-adjacent room or enclosed verandah. External sliding doors often have the tallest tracks in the house.
- Your bathroom or laundry steps down, or has a raised lip to keep water in.
- You have timber sills between rooms, which are common in older Australian housing such as Queenslanders and renovated cottages.
- Flooring types change at doorways: tile to timber, timber to carpet, or a transition strip covering the joint.
- You want one robot to cover a whole level. Every threshold it can’t cross splits the map into zones the robot treats as separate.
How to measure: rest a ruler flat on the lower floor surface and read the vertical height to the top of the sill. Where there are two steps close together — a sill and then a second step — measure each layer; this is a “double-layer” threshold, and models rated for it state the two layer heights separately.
Threshold Heights and What They Mean
| Threshold height | Typically found at | What it means for a robot vacuum |
|---|---|---|
| Under 1 cm | Flooring transition strips, modern continuous floors | Check the model’s threshold rating |
| 1–2 cm | Timber sills, tile-to-timber joins | Check the model’s threshold rating |
| 2–4 cm | Older door sills, shallow step-downs, some door tracks | Look for a rating at or above your measurement — the Saros 10R’s and Qrevo Edge 2 Pro’s AdaptiLift™ Chassis are each rated up to 4 cm |
| Over 4 cm | Sliding door tracks, wet-area step-downs, double sills | Look for a rating at or above your measurement — the Saros 20’s AdaptiLift™ Chassis 3.0 is rated for double-layer thresholds up to 8.8 cm (4.5 + 4.3 cm) |
Ratings are per model and based on the manufacturer’s testing; actual performance may vary depending on environmental conditions. Check the height stated on the specific model’s product page against your own measurement.
How to Work With Thresholds at Home
- 1Measure first, then match the model. The tallest threshold on the level you want cleaned sets the requirement.
- 2Consider a threshold ramp for a sill above the model’s rating. A low-profile ramp turns a step into a slope; it needs to sit flush so it doesn’t become a trip hazard.
- 3Use the app for rooms you’d rather it skipped. If a wet area is better left alone, a No-Go Zone is more dependable than relying on the threshold to stop the robot.
- 4Consider one robot per level. Thresholds are a doorway problem; stairs are a different one. A robot cannot use stairs, so multi-storey homes need either a robot per level or a cordless stick vacuum for the rest.
Frequently Asked Questions
What does “threshold height” mean on a robot vacuum spec sheet?
It’s the maximum step height the robot is rated to climb, measured vertically from the lower floor surface to the top of the sill. It’s based on the manufacturer’s testing, and actual performance may vary depending on environmental conditions, so check it against your own measurement rather than treating it as a guarantee for every doorway.
What is a double-layer threshold?
Two steps close together — typically a sill followed by a second step, or two stacked transitions. Models rated for double-layer crossing state the two layer heights separately: the Saros 20’s AdaptiLift™ Chassis 3.0, for example, is rated for double-layer thresholds up to 8.8 cm, made up of 4.5 cm and 4.3 cm layers.
Can a robot vacuum cross a sliding door track?
It depends on the track height and the model’s rating. Sliding door tracks are often among the tallest thresholds in an Australian home, so measure yours and compare it against the model’s stated threshold-crossing height. A lifting-chassis model widens the range of tracks that can be crossed.
What’s the difference between a threshold and a door sill?
In everyday use they describe the same thing — the raised strip in a doorway. “Sill” tends to be used for a timber or purpose-made strip beneath a door; “threshold” is the broader term covering any raised transition, including tile edges and sliding-door tracks.