I am sorry, I know that I should not provide a revised answer, but would like to do so now that I have been researching the possible meanings of these words and have discovered that my previous answer is probably incorrect.
By ‘support timber’, I mean ‘rafters, beams and battens’.
If you Google “καδρόνια στέγης”, with the inverted commas, you will see pictures of square or round or rectangular beams that are suitable for use both as rafters and battens.
The following definitions of “καδρόνι”, “καδρονιάζω” and “καδρόνιασμα”, could apply equally for rafters or beams or battens:
http://www.greek-language.gr/greekLang/modern_greek/tools/le...
This is also the case with these definitions:
καδρόνι (το) ουσ.1) (χτ.) ξύλινο δοκάρι με τετράγωνο κόψιμο [< ιταλ.: quadrone] 2) (ξυλ., χτ.) μεγάλο και χοντρό ξύλο κατάλληλα επεξεργασμένο να έχει ορθογώνιο σχήμα

καδρονιάζω ρ. 1) (χτ., ξυλ.) επενδύω, στρώνω μια επιφάνεια με καδρόνια 2) επεξεργάζομαι κομμάτι ξύλου ώστε να έχει τέσσερις έδρες, το μετατρέπω σε καδρόνι

καδρόνιασμα (το) ουσ. 1) (χτ) η επίστρωση μιας επιφάνειας με καδρόνια 2) (ξυλ., χτ.) η επεξεργασία ενός δοκαριού ή ενός ξύλου έτσι ώστε να πάρει το σχήμα καδρονιού
The above definitions are from:
http://christosbletsas2.blogspot.gr/2011/08/blog-post_28.htm...
Therefore, I think that one cannot restrict καδρόνιασμα to apply only to rafters or only to battens and must describe it as I have done in my answer.


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Note added at 2 days14 hrs (2016-09-12 05:15:58 GMT)
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When cross-checking this answer, please be sure to do so for “καδρόνια στέγης” because the terms appear to apply equally to the timber used for floors, walls and roofs in Greek, whereas the corresponding English words are different for floors and roofs.

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Note added at 2 days15 hrs (2016-09-12 05:46:39 GMT)
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Although the Νέο Λεξικό Τεχνικών Ορών του Νικόλαου Πανταζή gives the meanings of ‘καδρόνι’ to be ‘rafter’ or ‘beam’, and the meanings of ‘δοκάρι’ to be ‘balk’, ‘batten’, ‘baulk’, ‘beam’, ‘scaffold’, ‘joist’, ‘lathe-batten’, ‘rafter’, ‘spar’, ‘strut’, ‘transom’, I think that this simply confuses the issue further, especially as the same dictionary gives the meaning of ‘δοκάρι στήριξης στέγης’ to be ‘straining beam’ and ‘δοκίδα’ to be ‘batten’, ‘beam’, ‘cross-girder’, ‘lathe-batten’, etc.

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Note added at 2 days16 hrs (2016-09-12 07:02:27 GMT)
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Needless to say, this revised answer is mainly based on the information given to me by experienced Greek architects described in my discussion entries of yesterday evening. Although they said that the term καδρόνιασμα applies mainly to the shaping of timber beams to be used as rafters in traditional style Greek homes, I have found additional information on the Internet to indicate that it is also used for the shaping of other categories of support timber.