畳 is the Japanese shinjitai form of 叠 (traditional 疊, 'to fold / stack'). It is not used in Chinese writing - always write 叠. In Japanese it gained the extra meaning 'tatami mat'.
register
Japanese variant only - appears in etymology notes and Japanese text, not in modern Chinese.
Components
ideograph
畳dié
to stack; fold (Japanese form of 叠)
Treated as one unit. The Japanese reform stacked 田 over a 且-like base; the layering itself pictures the 'piling up / folding' meaning, but the modern shape does not split into independent standalone parts the way 叠 does.
No stroke data for 畳; the glyph shown is your device font, so component strokes can't be highlighted.
