A noun for “roof” in The Etymologies of the 1930s under the root ᴹ√TOP “cover, roof” (Ety/TOP).
Conceptual Development: The Qenya Lexicon of the 1910s had a similar form ᴱQ. túpo “roof, cover, lid” under the early root ᴱ√TUPU (QL/95), with just the gloss “roof” in the contemporaneous Poetic and Mythological Words of Eldarissa (PME/95). It also had a couple of other unrelated words: ᴱQ. tel (teld-) “roof” and ᴱQ. telin (telimb-) “roof, covering” both derived from the early root ᴱ√TELE (QL/90).
A word appearing as ᴹQ. tyel “end” in The Etymologies of the 1930s under the root ᴹ√KYEL “come to an end” (Ety/KYEL). Its plural form tyeldi indicates a stem form of tyeld- (EtyAC/KYEL). In The Etymologies as published in The Lost Road this plural form as incorrectly given as tyelde (LR/366), but Carl Hostetter and Patrick Wynne corrected this to tyeldi in their Addenda and Corrigenda to the Etymologies (VT45/25). The word tyel “end” also appeared a couple times in the 1930s poem Fíriel’s Song (LR/72).
Neo-Quenya: In Tolkien’s later writings, the root √KYEL seems to have been revised to √TEL; see the entry on that root for discussion. Compare also 1959-60 telma “conclusion” vs. 1930s ᴹQ. tyelma “ending”. As such, I would adapt this noun as ᴺQ. tel (teld-) “end”.