nope , I was right - it was dBm. and max power as shown - 30 dBm @1000mW 2.4 ghz channel band
but, they can list it however they want. I would like to put a watt meter on it.
I keep it down on the lower setting around 150mW. Our laptops in the house are only 20ft away from the router. Even turn down that low, I still can take my laptop out to the garage and access it.
But back to the OP:
If you are building new and trenching in services, do as others suggest and lay a generous size pvc run just for "low voltage" runs such as Ethernet, phone, coax. Call it done and enjoy your new digs.