expression, ichidan verb
nail a crosspiece (to)
Literal phrase used in carpentry or construction for fastening a horizontal bar or batten with nails.
大工が窓枠に桟を打ち付ける。
The carpenter nails a crosspiece to the window frame.
Alternate spelling with 打ちつける in kana.
Compound of 桟 (さん, 'crosspiece, bar') + を + 打ち付ける (うちつける, 'to nail, to fasten by hitting').