This is one of the questions we are often asked about. So, as one of the leading suppliers of Dunlop foam in Sydney, we thought of giving some suggestions with regards to this.
There is no such specific formula for each and every cover. It certainly depends upon the kind of foam you will be using, whether the foam has polyester wrap, whether it is going on drop in seat and how much ‘give’ is there in cover and so on.
Let us first discuss about drop in seat. These are mainly available on the dining chairs. The finished seat pad needs to be drop in to the wooden frame that shall be quite close fit on seat pad. In such a case, the foam must be the size of board or frame which it’s going on. Anything extra would mean that seat pad wouldn’t drop in to space found on it. Having a drop in seat means a fixed fabric cover with tacks/staples to frame or board.
If there is any other seat pad where fabric is fixed to frame or board, we would advice having foam cut a bit bigger than the frame or board. In all the other cases, finished cushion must be bigger than cover its supposed to go in to.
If foam has the polyfibre wrap, then you should cut it the exact size of cover. The polyfibre wrap may give you that extra amount of space that’s needed for making the cushion appear nice. If there is no polyfibre wrap in foam, it must be cut a bit bigger than cover size.
Thus, if your cover measures for instance 18″ x 18″ x 2″ you must either order foam in those sizes and go for a 4oz polyfibre wrap on it or opt for a foam of 18.5″ x 18.5″ x 2.5″ measurement when there isn’t any polyfibre wrap. The cushions having the wrap have more rounded look on corners rather than plain foam that has more of a block look.
You should be aware that foam doesn’t make a cover bigger than it actually is while being stretched but if you only order the foam just the exact size of covers, it may look baggy.