Finally, I have caught the bug! LOL

Exception in thread "AWT-EventQueue-0" java.lang.InternalError: Surface not cachable
at sun.java2d.xr.XRPaints$XRTexture.getAccSrcSurface(XRPaints.java:211)
at sun.java2d.xr.XRPaints$XRTexture.isPaintValid(XRPaints.java:224)
at sun.java2d.xr.XRPaints.isValid ...

Thanks for the suggestion but you should know that if Sweet Home 3D installer doesn't come with a copy of Java 8 yet, it's because of this bug .

Dear Emmanuel,
I played a couple of hours with SH3D that I modified and I could NOT reproduce the bug you pointed out.
I made my own >10MB home plan ...

Dear all,
I just fixed working Sweet Home 3D on Ubuntu 15.04 (Vivid Vervet)

OS: Ubuntu 15.04 (Vivid Vervet) 64 bit
Java: Oracle's Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
Java 3D and : 1.6.0-pre12-daily-experimental, upgraded according to information in https://gouessej.wordpress.com ...