Question:

Is a 25kg/m3 foam cushion good for a couch? That is all the seller told me and all the articles I’ve read online aren’t helping much.

I don’t want something that will sink when you sit on it. Also the seller is saying there are springs under the foam as well.

Is that confirmation of a good firm seat cushion couch?

Kris

Nov. 28, 2020

Answer:

Your foam density is given in the metric system. (Are you in Canada or Europe?)

25kg/m3 is equivalent to 1.8 density. That is the standard density for cushions found in most furniture stores. It has an average lifespan of 3 – 5 years before losing its resilience, firmness and comfort.

Firmness has nothing to do with lifespan. 1.8 density cushions can start off very firm, but will begin to soften up within less than a year.

2.5 density cushions (35kg/m3) may start off with the same firmness, but will not begin to soften for about 5 years with a lifespan of 10+ years.

All of that changes if your cushions are built with springs inside.

• Spring down or spring fiber cushions usually last for 10+ years.
• The density of the foam border around the springs is less important since your weight is mostly on the springs rather than the foam.
• You probably do not have this type of coil spring cushion construction since they rarely list foam density.

Your salesperson is probably referring to springs that are in the seat support foundation under the cushions. Those have little effect on cushion lifespan.

If the salesperson was not more explicit about the springs they are probably sinuous wire, which are very cheap and will last 20+ years but do not add any additional comfort.

Coil spring or 8 way hand tied foundations help soften the feel of the cushions, but are usually found only on high end sofas.

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