[BLENDER TO SFM] Inverted textures?

[THN Productions]

I've made a train cart model in blender and ported it to SFM, however, in SFM, the textures are all inverted. For example the exterior of the walls is in the interior and the interior in the exterior, same for the front texture, floor texture, doors texture and roof texture. I've noticed while texture painting directly to the mesh will paint it on the other side, but never thought anything of it. How do I fix this?
Pics:
How the model is supposed to look like:
https://gyazo.com/73838e040a0ae1f7a579c0dc9d06c890
https://gyazo.com/6b686e5e63baea0f64e5b35dae502558
https://gyazo.com/8985def22de329f47f531d40fef65752
But this is how it turned out in SFM:
https://gyazo.com/03b72f6701f7dc0a039d4a529bd17092
https://gyazo.com/f2986ef1be21b260fafdfcd005f9a578
https://gyazo.com/ecb7005ccc250958f63b0953a0e5dc19 (that's the roof part of the texture that's supposed to be on the outside)
https://gyazo.com/5981bf1a9fa87c4591e6003c8fec634b (that's the ceiling part of the texture that's supposed to be on the inside)

[episoder]

enable backface culling in blender. it's in the viewport properties (n) under display.

[THN Productions]

I'm pretty bad with the layout, could you provide a picture of where it is located?

[THN Productions]

Ah I got it, had to press n on the keyboard, but I found it under shading not display, hope that's still correct. I'll export this again.

[THN Productions]

I enabled backface culling, exported it and used the same QC as before to compile it, but it has the new SMD files. Didn't change anything for the materials either. It still shows up inverted in the model viewer, haven't checked SFM yet but I doubt it'll be different. What did I do wrong?

[episoder]

how does it show up in blender? i mean you gotta fix inverted faces in blender first and then rexport. i thought you'd get that it may look wrong in blender. guess not.

[THN Productions]

It did look "wrong" in Blender, exactly how it looks like in the SFM pics I showed above. I enabled that and then exported, is that what you mean by fixing inverted faces or something else?

[episoder]

you dunno how to fix inverted faces? just select the wrong ones and invert normals in the tool sidebar in the uv tab.

[THN Productions]

I selected the faces and then used the Ctrl + N shortcut cause I couldn't find it in the tools sidebar. Looks perfect in the model viewer, so probably in SFM too. Thanks!