कच्चे मकानों, झोपड़ियों आदि की उस छाजन को छप्पर (thatch) कहते हैं जो बाँसों, लकड़ियों तथा फूस की बनी होती है। किसी प्रकार का आवरण जो रक्षा के लिए ऊपर लगाया जाय, उसे भी छप्पर कहते हैं; जैसे-नाव पर का छप्पर। इसे संस्कृत में छत्त्वर, प्रकृत में छप्पर, बंगला में छापर, ओड़िया में छपर, गुजराती में छाप्रो, नेपाली में छाप्रो और मराठी में छप्पर के नाम से जाना जाता है।

Thatching is the craft of building a roof with dry vegetation such as straw, water reed, sedge, rushes, heather, or palm branches, layering the vegetation so as to shed water away from the inner roof. Since the bulk of the vegetation stays dry and is densely packed—trapping air—thatching also functions as insulation. It is a very old roofing method and has been used in both tropical and temperate climates. Thatch is still employed by builders in developing countries, usually with low-cost local vegetation. By contrast, in some developed countries it is the choice of some affluent people who desire a rustic look for their home, would like a more ecologically friendly roof, or who have purchased an originally thatched abode.