The first line of defense will be a wide open expance which can be watched over easily from a lookout on a roof, silo or even an old gravity fed gas tank for at least a mile in any direction. The fields furthest from the house will be low lying crops, like soy. Closer up you’d have the corn grown in small sections with 20 foot paths between them. This is so, that it’s easier to track the zeds movements if they get that far.

A simple barracade would initially be built around the house eventually being built into stone and dirt ramparts, that can also be the main artery for irragation ditches. The lower level windows would need to be sealed with brick, leaving maybe gun ports here and there. The doors would then be replaced by heavy fire doors with a reinforced frame. Since alot of these far houses have the outside cellar door, that would have to be either sealed, replaced with heavier doors or a second door put into place.

Although this may seem like a fortress the big part of this system is that the open expanse allows for wide open escape if there’s just to damn maney of the dead out there to deal with. Given around 10+ people it would allow the house to be defended from upto a couple hundred zombies at a time with the ditch and rampart functioning as a shooting gallery or even the use of spears if needed and if or when they get past those there is still the house to fall back to if things aren’t hopeless.

Personally I think I’d head for the army base in Tacoma - grab a Stryker (majority of the stryker units in the US army are stationed there) and head for the naval base on the otherside of puget sound. Plus there are all the ferry stations here which a ferry isn’t great for survival but it gives you a safe platform for a day or two, plus you could head for one of the islands in the sound to hold up and defend yourself.