Revit is one of a kind in this regard...

[scramer.118425]

It's the only program I've ever used that increases in file size when you delete things.

!?

[patricks]

It's probably remnants of the object it's storing somewhere, maybe instance data or something, for whatever reason. If you save the file and check the box for Compact File, you should see it get significantly smaller.

[lev.lipkin]

Thanks for good explanation.

In addition, Revit does not load unused elements into memory, and on deletion some of those elements have to be loaded to get properly updated. Hope that it now makes sense to you.

[TroyGates]

Its also typical of most database programs to inflate the files with 'white space'. These are empty records that the program can write to without having to increase the file size, which helps on performance. Not sure if Revit employs the same technique or not.

[Rustle]

I think it decompresses things that are attached to the deleted object so it gets bigger until you compress it again. I just found a project running around the office that had gotten up to 206MB. I audited it and it came down to 146MB. Then I purged 3,500+ items and it went up to 246MB!!! When I compressed it went down to 101MB.

[Scott D Davis]

Don't look at file sizes when Revit has a file open...it'll be double the size or more. Close the file, then check file size. Doing a Saveas from time to time will help reduce file size as well.

[wjspence]

I typically do a save as once a week to keep the size down. This morning the file went from 50 mb to 28 mb. That seems to be a typical proportional size reduction.