I bought a sectional seagrass sofa from Pottery Barn for a lake house that has individual cushions. The cushions are 3 1/2 thick and very lightweight foam! They sit on the frame( 6 ) and everyone complains it hurts their bottoms!
Should I try putting a much denser cushion in the Sunbrella coverings? The sofa isn’t even a year old BUT NEVER COMFORTABLE! Help!
May 31, 2020
Sunbrella fabrics are excellent quality, virtually stain proof, and resist fading from sunlight better than almost any other fabric, but they will not improve the comfort.
The seat cushions are described as “highly resilient foam core, wrapped in lofty polyester batting.” The lack of any additional information about the foam indicates that the density is probably the industry standard 1.8 with an ILD (firmness rating) of 36.
The 3.5 inch thick foam compares with 5 inch (or thicker) foam cores found in most residential sofas with removable cushions. The added thickness increases cushion durability. It also provides much needed additional padding which softens the feel of rigid suspensions such as sinuous wire or webbing. (According to the Seagrass description, your sofa uses synthetic webbing.)
On high end residential furniture, thin cushions like this are generally filled with very soft down and feathers. But they rest on flexible coil spring or 8-way hand tied foundations that work with the down/feather cushions to provide a comfortable seat.
Down/feather cushions are far more expensive than the foam/fiber cushions you currently have. Switching the cushions to down/feathers will improve the “feel,” but probably not enough, in combination with the webbed foundation, to make the sofa comfortable.
The other high end option is to use spring-down cushions, but those need to be considerably thicker than 3 ½ inches.
Re-building the foundation to use coil springs instead of webbing would be prohibitively expensive.
As you have suggested, replacing the existing foam with higher density foam should improve the comfort. Normally 2.5 density with an ILD (firmness) rating of 35 is sufficient for residential seating, but in this case the cushions are so thin that something of even higher density and firmness is called for.
Even though the seats currently feel too hard, part of the problem is that the foam is too soft, allowing you to feel the hardness of the foundation beneath the cushion. Higher density foam with a higher ILD (firmness) should improve the overall comfort.
Below is my recommendation: High Quality Lux Foam with Fiberfill Dacron Wrap. You can find this online at FoamFactory.com.
If you do additional research you may be able to find foams with densities of 3.0 – 3.5. Those should work as well.
Memory foams work on a different scale. A 3.0 density polyurethane foam is equivalent to a 5.0 density memory foam.) Memory foams are far more expensive. Not all memory foams are suitable for use in cushions. Normally memory foams are used in cushions only as a thin layer glued to the top of a thicker polyurethane foam core.
The foam cushion replacement suggested below may not result in a cushion that is as comfortable as you prefer, but it should be a definite improvement over what you have now.
Lux Foam – High Quality
Firm to extremely firm foam depending on thickness. Thicknesses from 1″ to 5″ are considered firm and thicknesses from 6″ to 8″ are considered extremely firm. This foam can be used for regular or heavy use. Lux Foam-HQ is a high quality foam suggested for seats, chairs, cushions, benches, and mattresses. It has a typical life of 16 years.
(2.8LB /ft3 density with a 50LB ILD)
It is highly suggested that you also use the Fiberfill Wrap around the foam core. Adding the fiberfill does not decrease the thickness of foam needed. It will help fill out corners and surfaces so that the fabric cover fits properly.
Fiberfill Wrap (Dacron)
Polyester fiberfill wrap is highly suggested for foam cushions. Without reducing support, it adds extra comfort to the cushion while snugly filling out the cover. If this option is selected, the cushion will come with a 1″ thick layer of fiberfill that wraps around the entire cushion, not just the top and bottom surfaces. Fiberfill may also be purchased separately under the Accessories section of our website.
IMPORTANT: Do not reduce your measurements to compensate for the addition of fiberfill wrap. Fiberfill will not affect the fit of your cover(s).
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