Properties and Benefits: Cob bricks have a high density that gives them a high thermal mass and sound insulation. They are well suited for modern buildings as well as old. Cob bricks absorb odours and water vapour. Cob also has the property of keeping surfaces cool in summer and warm in winter. Cob bricks can be bedded in a clay or lime mortar. An appropriate finish would be lime or clay plaster, lime rendered for external walls.