I opened the trapdoor to the underfloor storage and put away the vacuum cleaner.
When you remove the counter's lift-up lid, you can see the plumbing.
Standard kanji spelling for a lift-up lid or trapdoor.
Alternate spelling using 上 (up/above) instead of 上げ (lift).
Kana spelling is common in everyday writing when the kanji is not needed.
Rarely used kanji form; 揚げ implies deep-frying, which is unrelated to the meaning.
Compound of 上げ (age, 'lifting') + 蓋 (futa, 'lid'). The spelling 上蓋 uses 上 (ue, 'up') instead of 上げ, but the reading remains あげぶた.