What is the weight limit on the Birch Foundation? February 18, 2021 18:13 The Birch Foundation can support up to 1,200 pounds. Related articles How much space is between each slat on the Birch Foundation? What is the Birch Foundation made from? Does the Birch Mattress require a foundation? What’s the difference between Birch and Birch Luxe? How is the Birch Foundation assembled?