snap it to a large gate

引用自 DocSlob：

snap it to a large gate

I was trying to snap it to a large gate...

you can use the gate posts instead which can be free placed in the ground

Gate Posts = free placement on the ground - same as vanilla gates
Gate Frames = Snapping as a wall for use within a building

Okay let me try explaining what happened here...

I had a frame/post in place already. It was there, waiting to be snapped to.
The Porticullis however would not allow me to put it there (Despite it obviously already appearing, waiting to be placed) and instead gave me the "Needs foundation support".

I was NOT having problems with a frame.
A frame was ALREADY in place.

This was an issue 2 weeks ago now.
I believe that it WAS posts I was trying to use even... Considering that an arched frame was not ideal for the situation of building I was using.

I am also having this exact same issue, has a solution been reached? I'm trying to place a portcullis as the front door to my main keep, I have foundations (I've even tried surrounding it with them) and I do have the large gate posts for it to snap to, but no matter what I try it won't let me place it.

You have to snap a large portcullis to a gate frame. You can find the large gate frame in the walls tab. Only the doors seem to work with the gate posts.