I've been doing amazing stuff in FreeCAD. It has a lot of power that lets me do things I never thought I would be able to do. It's also riddled with bugs that will make you want to throw your computer out the window.

My success with FreeCAD comes from extremely strict version control and years of use. I've learned to live with a few specific bugs. For example, external geometry doesn't work and hasn't for 14 months. Don't believe the forum when they say it works. It does not. In any given sketch, you will be able to make is 0 or 1 external link work properly without breaking your drawing. If you have more than one external link, even if you aren't using any of them, it will give you a "wire not closed" error when trying to pad or pocket.

Oddly, the subshape binder works perfectly and it is the illegitimate brother of external links. It even uses the external link tool to define import links from the binder object. Using a master sketch and the subshape binder is absolutely brilliant and wildly productive.

It comes down to having several tools to do any given thing but only one or two may be working.

There is a decent architectural plug-in for FreeCAD. I think Yorik wrote it, some time ago, but it's brilliant. I've used it for doing exactly what you describe on several house projects and it's helped quite a bit with renovations.

SweetHome3d is also a decent app but extremely primative and it's not going to create professional looking blueprints for anyone. It's really just a toy but can be extremely useful for mocking up a design or room layout. I have used it for years with great benefit. It's simple, quite powerful, and a brilliant visualization tool.

Honestly, if you want to create real blueprints to give to a builder, you're going to need Windows or OSX and one of a handful of applications, preeminently AutoDesk REVIT. REVIT is probably over specified for your purpose but it's the adult table. At least, know it's there if you find linux apps have too many shortcomings.