You really should start at the beginning with this, first find out at what frequency and at what maximum power you are allowed to build a transmitting device in your country (Philipines). These laws vary from country to country.
Then, when you have found out if you can do that legally without a radio transmitting licence you start looking for a circuit that works on these frequencies, there certainly will be a limit how much RF power you can transmit.
Then you find out if that frequency is suitable for being picked up within buildings, some buildings make an effective shield for low power transmitters.
Then you find a receiver that can cope with this signal.
Then, if you are still keen to go ahead, you do a search how commercial fire alarms cope with remote monitoring. You may find that they operate via hard wiring as radio signals are too prone to false alarms or malfunctions.
Then you wonder why you did not do your homework first :lol:, its all very well to get an idea for a project but reality is often a real killjoy.
Klaus