Are you talking standard WiFi access points here?
The installed antennae on all APs are just about useless, a cheap upgrade to a decent omni-directional should give you pretty much full house coverage from a single AP, unless you live in a castle obviously..
Do you have something to test connectivity with, say a laptop?
I'd UG the Antennae on your existing AP ( if possible) and give that a try before you start cutting any holes....
Have a look at the ones here:
Solwise
You could maybe try the NET-WL-ANT-012CN, mounted high up in the roof and firing downwards, or just about any of the Omni-Directional if you're in a single floor building.. You should easily get full house coverage.
Something like a 8-10db Omni should be enough, and they're not pricey..