Lakeview Extended - Hearthfire SSE Basement in Windstad Manor and Heljarchen Hall
I have used this mod in my own game for quite some time and have seen requests for something like this in the Lakeview Extended - Hearthfire SSE posts section. So I sent a PM to Ac3s about it and he kindly gave me his permission to publish this.
You can find the Oldrim version of the Mod here.
It works well with follower mods like My Home is Your Home, etc.
However, getting it to work is an issue that you will have to resolve yourself.
I added the basement to Heljarchen and Windstad and had to navmesh the area. I was careful not to put navmesh under anything so followers will not bump into tables, chairs or beds while sandboxing. However, the vanilla navmesh in the Cellar isn't as neat and Bethesda isn't as careful as I am. I made no effort to clean up the navmesh in the cellar that was under everything.
Navmesh in the Hearthfire Homes is an issue. You will notice sometimes an NPC will spawn stuck standing on top of a chair. This is because there is navmesh under it. They will also sometimes bump into tables and chairs while sandboxing. This is because the navmesh is everywhere and they think they can walk there. This isn't something I caused, they don't call them Bugthesda without good reason...
There are two versions of the mod.
All in One (The X3 version). This is for a New Playthrough. It contains the Basement for all three homes. Do Not Install the Lakeview Extended Basement mod with this one.
The X2 version. This is for an Existing Playthrough where you already have the Basement installed in Lakeview Manor and you just want to add the basement to Windstand Manor and Heljarchen Hall.