Just six zombies? I'd throw on my shoulder rig with my .357 mag revolver, throw my 12 gauge over my shoulder on a sling (these are for later), stick a hammer in my pocket, and grab my Mossberg .702 plinkster with a few full mags, and take the initiative by taking out the zombies through the door. Keep the chain on the door, let it open. Shoot through the gap to take down the first few zombies, hopefully before they can break the chain. If the chain holds up, the bodies of the first couple of zombies should stop the further ones from putting too much pressure against the door, giving me more chance to pick off the remaining zombies at my leisure. I've noticed the .22 doesn't produce a very directional bang, but mostly just a sonic boom, which is hard to determine direction from. Fired indoors the sound is going to be muffled even more. It may be low power, but at close range it should still do the job.
Should the chain fail, I can fall back to the bathroom (no windows, one door, and access to the attic) and use the open door as a bottleneck to draw the zombies in to finish off the remaining ones. If that's successful, I know the house is no longer secure, grab BoB, and I can head for the car, which is thankfully packed for at least some emergencies, with tools and first-aid, and head for higher ground and sparser populations, via back roads to avoid likely clogged highways.
If the bottleneck plan fails, I can climb into the attic and hole up, picking off as much of the hoarde as possible. If it turns out to be more than six, or the house is surrounded, I can just close up the attic and hunker down. It's not the most pleasant place, but zombies can't reach it, there is a potential escape route, including the ability to jump down straight to the car. Let's hope I remembered my keys.
Basically my strategy is the time tested means for one person to take on a group, which is create a bottleneck where you force your enemies to come at you one at a time, on your own terms, turning a siege defense scenario into just six single zombie encounter scenarios in rapid succession. The plan does hinge on the idea that .22lr won't make enough noise to attract a large group too quickly, but also allows for switching to higher power weapons if the .22s prove insufficient. The weak point is probably the layout of the house. It's a flat design, no second story, two entrances, large windows, and no hallways. There's just too many weak points, requiring a more active defense plan, which is why my plan incorporates creating an opening in one place to draw the Zs in on my terms rather than wait for incursions in multiple locations.