Down envelopes will cause the overall cushion to finish approximately 3" thicker at its peak in the middle of the cushion and gradually taper down to the edges. This overstuffed look is called a crown and is normal. A poly down envelope will finish 3"–5" thicker since the poly fibers have a greater loft. You can reduce the total cushion thickness by reducing the thickness of the foam inside. Don’t reduce the thickness of the down envelope. Down envelopes need room to expand, so having foam that is 1" thinner than the actual down envelope works best. Down envelopes need to be ordered the same dimensions as the outer cover to fill out the outer cover properly (and always choose the option to “add allowances”).
If you don’t want such a large crown then add to the comments section in the shopping cart that you want your foam 1" thinner, and this will lower the crown by 1". You may order the foam up to 2" thinner than the down envelope without much consequence to aesthetics. Certain combinations of foam and down are best in these circumstances, so call our sales staff for recommendations.