My wife and I retired to AZ 10 years ago. We both have bad knees and she also has a bad hip. Our house in AZ has ceramic tile floors, except in the bedrooms. The house is built on a concrete slab. Talk about a hard floor! The solution to hard floors is to wear very soft spongy soled shoes in the house all of the time. There are a few models of Skechers shoes which have extremely soft soles. With these shoes, there is no need for carpet, rugs, or cushioned floor mats to eliminate the shock on the joints.

We are planning to remove the old carpet in all of the bedrooms. I’ve been researching flooring for the past 5 weeks and have decided to go with a wood-look rigid core vinyl plank that locks together to make a floating floor. (Beware, these interlocking rigid floors require a very flat subfloor. If the subfloor is not really flat, it will have to be flattened before the new rigid vinyl planks are put down. Might want to read the installation instructions before you buy the flooring.) As you know, most of these products have one of two kinds of cores, Wood Polymer Composite (WPC) or Solid Polymer Composite (SPC). SPC is also used to stand for Stone Polymer Composite. The polymer is usually PVC, in other words, vinyl.

It appears to me that most of the new rigid core vinyl plank flooring products that have been introduced during the past 7 years use an SPC core or some minor variation of it. That suggests to me that SPC is better or perhaps cheaper to manufacture. I have looked at WPC & SPC products. For some applications I don’t think it makes much difference. We will probably end up with an SPC product but not because of, or in spite of, the kind of core.

All of the products we’re considering have an attached underlayment/pad that absorbs a little shock. Some are cork, some EVA foam and some IXPE. Thickness varies from 0.5mm to 1.5mm.

SPC is more dense. It has less air in it. It expands and contracts less due to changes in temperature. Consequently it is better than WPC if the flooring will be exposed to a lot of direct sunlight, especially in the summer. It’s also best if the ambient temperature varies considerably, such as a house that is not heated and cooled year round. Because SPC expands and contracts less than WPC, SPC is better for very large rooms or long runs, say from one end of a house to the other end. SPC requires fewer expansion strips if you’re trying to cover the entire floor of a house with the same flooring product.

Floors made with SPC cores may expand and contract less from exposure to the sun, but that doesn’t make them more resistant to fading.

Makers of WPC claim that SPC is colder underfoot. I think the difference is undetectable or negligible, when touched by a bare hand. It’s totally irrelevant if you wear shoes or socks all the time.

Lastly, products made with SPC are more resistant to compression due to high pressure over a short period of time. I think this is a proxy for the pressure from very heavy furniture over much longer periods of time. SPC floors are also more resistant to sudden momentary impacts from heavy objects.

Today I tested 4 WPC products:

1. Home Depot Lifeproof, 7mm, 1.0mm IXPE pad, Dusk Cherry, #106204L
2. Lowe’s SMARTCORE Ultra, 7.5mm, 1.0mm pad, Savannah Oak, #1035196
3. COREtec Plus Plank 5”, 8mm, 1.0mm cork pad, Weldon Oak, #00509
4. Provenza, Uptown Chic, 8mm, 1.5mm IXPE pad

I’ve listed the color names when available but I don’t think the color affects the resistance to dents and impact.

I also tested 4 SPC products:

1. Armstrong PRYZM, 6.5mm, 1.0mm cork pad, Antiqued Oak Natural, #PC003
2. SUPERCore Xtreme, 6.0 mm, 1.5mm EVA pad, Wagon Wheel, #SPC023X
3. Flooret Modin Base, 5.0mm, 1.0mm IXPE pad, Kingswood
4. Karndean Van Gogh, 4.5mm, 0.5mm pad, Jatoba, #SCB42

Note that all of the SPC products were thinner than all of the WPC products

The first test applied 205 lbs to 0.02 sq inch on the face of each sample. That's about 10,000 PSI. The pressure was applied for 1 minute. All 4 WPC samples performed about the same. All 4 SPC samples performed about the same. Every SPC sample out performed every WPC sample. The dents on the SPC samples were extremely small, barely visible under very good light.

The second test involved dropping a steel rod from 2”, 3” & 5” vertically onto different spots on the face of a sample which was flat on a 4” thick concrete slab. The rod had a diameter of ¾” and weighed 3.5 lbs. It was 30” long with a 3/32” diameter point on the end. In all cases a longer drop resulted in a deeper and more visible dent. Three of the WPC samples performed essentially the same. The COREtec Plus didn’t fare quite as well. In this test the SUPERCore Xtreme slightly outperformed the other SPC samples, probably because of the thicker underlayment of SUPERCore. Again all SPC samples outperformed all of the WPC samples. The sheen, color, and texture of the surface, affect the visibility of the dents but not the depth. The thickness and kind of attached underlayment probably affects the depth of the dents slightly.

SPC and WPC planks can be made with the same wear layer, protective top surface coat, surface texture, surface sheen, edge detail, and attached underlayment. All of these attributes together probably affect how the product performs and wears. And of course resistance to impact is only one of many criteria upon which to choose rigid core vinyl plank flooring.

If you want a thick floor, you’ll probably want to go with WPC. If you want a quiet floor for the person walking on it with hard heels and soles, I don’t know. Probably won’t make any difference with rubber soled shoes. What do the rest of you think?