Do I need a transit visa for UK to change terminals at LHR?

I am traveling from India to Phoenix through British Airways with a valid US visa (F1).
I have a connecting flight at the Heathrow airport. I will arrive at Terminal 5 and will need to commute to Terminal 3.
I won't be checking in baggage.
I asked BA customer support but they didn't clarify if I would cross border control at UK. So, do I need a UK transit visa? If yes, do I need a DATV or a visitor-in-transit visa?
Also, is 2 hrs 25 mins enough to complete security check and change terminals?

As far as I know there are free transportation buses that go from Terminal 5 to Terminal 3. But I don't know for sure if that travel is considered "airside" (no transit visa required) or "landside" (transit visa required).

PS: I know there are some similar questions (this, this) but they are too old (rules may have changed).

uk transit-visas

Pictures about "Do I need a transit visa for UK to change terminals at LHR?"

Do I need a transit visa for UK to change terminals at LHR? - Young couple standing in front of train on metro station platform

Do I need a transit visa for UK to change terminals at LHR? - Side view of unrecognizable young man and woman in trendy outfits and backpack looking away while waiting for train in underground station

Do I need a transit visa for UK to change terminals at LHR? - Public railway station with clock in center

Do I need a UK visa for a connecting flight in Heathrow?

You might need a Visitor in Transit visa if you're: changing flights in the UK on your way to another country. going through UK border control, for example to check in your luggage for a connecting flight. leaving the UK within 48 hours.

Is transit visa required to change airport in London?

If you are passing through a UK airport while on the way to another country, you may need a UK transit visa. Transit visas are required by some nationals who are passing through the UK en-route to another country within 24 or 48 hours.

Do I need visa for connecting flight in Heathrow?

You usually only need a transit visa if you want to leave the airport as you have a long layover. 3. Re: Is Transit Visa Required at London(Heathrow) Airport? "You usually only need a transit visa if you want to leave the airport as you have a long layover."

Is transit visa required for terminal change?

No, you need not apply for a transit visa if the two flights are from the same terminal and if you have only two hours in between the two flights.

Do you really need Transit Visa for UK

Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.

Images: 39422Studio, Samson Katt, Samson Katt, Charlotte May