The double-sided Plank Firm is a flat, firm mattress designed for sleepers who want strong support with minimal cushioning. It claims to be the 'firmest mattress ever' but is that true? Our sleep team went hands-on with the Plank Firm at 3Z Labs in Arizona to see if this specialist mattress delivers on its promise. Here's what you need to know...
Plank Firm mattress specs
Type: All-foam (dual-sided)
Firmness (1-10): Firm side 8 (we rate it 8); Extra firm 10 (we rate it 9)
Height: 9"
Trial period: 120 nights
Warranty: 10 years
Sale price: From $561 at Plank Mattress
Our first impression is that, yes, this really is a hugely firm bed. But despite the unyielding feel, the Plank delivers more comfort than you might expect. What's more, it's a flippable mattress, with one side delivering slightly more contouring.
We use a long mattress testing period to determine which beds have earned a place in our guide to the best mattress of the year. While we were unable to spend quite as much time with the Plank Firm, members of our experienced sleep team were able to inspect and lie on the mattress, as well as complete objective tests, of which you can read the full results below.
Our verdict? The Plank Firm isn't for everyone, but our testers were surprised by just how many sleep styles it suits thanks to its dual-sided design. Monthly mattress sales knock a queen-sized Plank Firm to $999 or less, which is a solid value, considering you're essentially getting two beds for the cost of one here.
Chances are we'll see the Plank Firm fall in price even more during this year's Black Friday mattress deals, but does that mean you should buy it? Read on for our Plank Firm mattress hands-on review to learn who we'd recommend this specialist bed to and who should avoid it...
Plank Firm mattress: Price
- Sits in the mid-range price bracket, a queen is usually $999
- Evergreen 25% off sale increases to 30% around major holidays
- Available in a large range of sizes, including RV beds
A queen-sized Plank Firm has an MSRP of $1,332, but frequent mattress sales reduce it to $999. In the wider mattress market, it falls into the mid-range price bracket, and it's competitively priced for a specialist double-sided bed.
Below are the MSRPs for all sizes of the Plank Firm, with the prices you can expect to pay after a regular saving of 25%:
- Twin MSRP: $749 (normally on sale for $561.75)
- Twin XL MSRP: $849 (normally $636.75)
- Full / short full MSRP: $999 (normally $749.25)
- Queen / short queen / Olympic queen MSRP: $1,332 (normally $999)
- King / Cal king / short king MSRP: $1,532 (normally $1,149)
- RV king (72"x80", 70"x74", 70"x80") MSRP: $1,532, (normally $1,149)
The Plank Firm is available in an extensive size range, including multiple RV sizes and alternative queen, king, and full sizes. This is useful for anyone who has an unusually shaped bed and struggles to find a mattress that meets their needs.
An evergreen discount saves you 25% on all sizes of the Plank Firm, but for the best deals you need to wait for major holidays. During Memorial Day and Labor Day 2024, the discount increased to 30% off, and it will likely be 30% off again for the Black Friday and Cyber Monday mattress sales.
Plank Firm mattress: Design
- A 9" double-sided all-foam mattress
- Extra firm side has a mostly flat quilted surface
- Firm side adds a 2" comfort foam layer and minimal loft
The Plank Firm mattress has an unusual build, due to the fact that it's technically two beds in one. Use it one way round, and you'll be enjoying a firm surface. Flip it the other way and you'll have an extra firm mattress to rest on.
The extra firm side employs a simple design that allows the 6" high-density support foam core to do most of the work. It's capped by a .75" quilted top, which is responsible for the (minimal) pressure relief on this bed.
When you flip the mattress over to the firm side, you'll find a 2" layer of comfort foam on top of the high-density core, bringing some contouring and pressure relief to the surface. The firm side is likewise finished with a .75" quilted top. If you need extra cooling, upgrade to a GlacioTex cover for both sides.
Two different quilted designs indicate which side you're sleeping on, and also affect the overall feel of the bed. On the extra firm side, a continuous pattern stitch limits the loft for minimal padding. On the firm side, track and jump stitching keeps the loft low but allows for a little more plushness.
However, some more distinction would have been appreciated as the loft looks the same on either side at first glance. You might find yourself flipping the bed one way to the other just to make sure you have it on the right side.
Despite being double-sided, the Plank is relatively thin for a mattress. It measures only 9 inches tall, slightly under the 10-inch mattress thickness we recommend for adults.
Plank Firm mattress: Comfort & pressure relief
- Extra firm side is 9/10 in firmness; we like it best for back sleeping
- Firm side is 8/10 in firmness; it's our choice for stomach sleeping
- Heavier side sleepers may find the firm side comfortable, too
As a flippable bed, there are two different feels to the Plank Firm. One side is extra firm, and it really does live up to its name. Plank rates the mattress as 10/10 on the firmness scale, but our team feel it's closer to 9-9.5/10. We rate 10 as hard as a rock; the extra firm side has just a touch of give to the surface to drop it down a notch.
That hardness does give the extra firm side a limited appeal. There's almost no pressure relief for side sleepers, and our lightest tester couldn't get comfortable at all in this position. In fact, none of our panel enjoyed side sleeping on the extra firm side, and we would expect some numb shoulders in the morning.
Surprisingly, we also struggled to get comfortable when front-sleeping on the extra firm side. The best mattresses for stomach sleepers are typically firm, but our testers found the Plank a bit too hard. It pushes against the stomach, which might get uncomfortable after a big meal, for example.
For our testers, the extra firm side excelled at back sleeping. The dense support holds the lower back in alignment, with the slight quilting filling the gaps in the lumbar region to help support the spine.
The firm side is immediately softer but still quite solid. Plank rates the Firm as an 8/10, and our testers agree. There's some plushness thanks to a loftier quilt and a layer of comfort foam, but it's a decidedly firm mattress otherwise.
This plushness ensures the firm side is better for side sleeping, although it can't compare to the pressure relief of the best mattresses for side sleepers. However, those with a heavier build might appreciate the lack of deep sinkage.
Our testers think the firm side appeals to front sleepers. Our dedicated stomach-sleeping tester enjoyed the support at the hips and liked how the slight plushness soothed the pressure points. Back sleeping is also supportive, although our testing panel felt this might be a mattress to break in as there was some fidgeting to get in a comfortable position.
Plank Firm mattress: Performance
- Sturdy edges on both sides
- Better than average motion isolation
- Surprisingly lacks handles for easier flipping
To complete our hands-on review we followed the testing process in our mattress methodology, testing the edge support, motion isolation, and temperature regulation for both sides of the Plank Firm mattress. Here's how we got on...
Edge support
If you like to sit on the side of your mattress when getting ready, you'll benefit from good edge support. Strong edges can also help those with limited mobility, as they provide a stable base to push against when getting out of bed.
To objectively test the edge support of the Plank Firm, we placed a 35lb weight on the side and the corner for both sides. On the firm side, we observed a 2" sink at the sides and 2.5" at the corner. This is comparable to the sink in the center of the bed, and all our testers felt comfortable sitting or lying on the sides.
As for the extra firm side, the weight hardly sank. We measured just a 1" drop at the side and only 1.5" at the corner. Our objective testing backed this up — the Plank Extra Firm has a secure and steady perimeter. It's so strong, you could comfortably use that side as a sofa.
Motion isolation
We used both objective and subjective testing to determine how well the Plank Firm isolates motion, allowing you to sleep soundly even if your partner tosses and turns.
For objective testing, we balanced a wine glass in the middle of the bed (where a person would sleep). We then held an 18lb weight 4" above the mattress and dropped it from 25", 12", and 4" away. When the weight dropped, we recorded the movement of the wine glass.
On both sides, the glass was still at 25", and wobbled slightly from 12" away. From 4" away, the glass fell over on the firm side. On the extra firm side, the glass stayed upright but did fall when we later repeated the test.
Our subjective tests showed similar results. We expect you can sleep through most movement on either side of the Plank Firm, but a hugely restless partner might cause some disruption.
Temperature regulation
It's hard to get an accurate read on temperature regulation, as we tested the Plank Firm in a climate-controlled showroom. However, we expect that the firm surface and lack of sink prevent the Plank Firm from trapping heat.
Very hot sleepers should consider upgrading to the GlacoiTex cooling cover. To learn how a GlacioTex cooling cover performs, check out our Brooklyn Bedding Aurora Luxe mattress review.
Setup
Our Plank Firm mattress was a floor model, so it hadn't been rolled and didn't need to be set up. However, we did need to flip the mattress and move it across the showroom floor, giving us a good perspective on how easy it is to move this dual-side mattress.
The slimmer build does make navigation slightly easier, but as this bed is designed to be flipped, some handles would have been appreciated. If you're considering this firmer mattress to help with back pain, we recommend getting a helping hand any time you want to go from firm to extra firm (and vice versa).
The Plank Firm comes with a 120-night sleep trial, which is slightly above average (100 nights is standard) ), so we recommend making the most of this trial period to see if you can adjust to the unusual feel. It can take 30 days to adjust to a new mattress, and as this is a double-sided bed, you might go through that twice.
Plank Firm mattress: User reviews
At the time of writing, the Plank Firm has over 3,400 reviews and a 4.7-star rating out of 5 at Plank Mattress. You can sort reviews by rating, date, and whether they include media (photo or video).
Most of the reviews are 5 stars and come from sleepers who like that it's actually a firm mattress. On the other hand, some critics claim it's softer than they'd anticipated, and a few customers say the quality of the materials could be better.
Should you buy the Plank Firm mattress?
Buy the Plank Firm mattress if...
✅ You sleep on your back or stomach: The Plank has a strong, even support on both sides of the mattress, keeping your body aligned from head to toe. You won't feel your hips or lower back sink out of alignment.
✅ Your support needs change: Double-sided mattresses allow you to change the feel depending on your needs. This is particularly helpful if you have a reoccurring injury that might change what feel benefits you best.
✅ You need strong edges: Sitting on the edge of the Plank on either side feels stable and secure. If you have limited mobility and need a boost to get out of bed in the morning, the Plank will provide a strong base to push against.
Don't buy the Plank Firm mattress if...
❌ You sleep on your side: There's minimal contouring on either side of the Plank Firm, resulting in little pressure relief. The firm side is less unyielding, but most side sleepers can expect an achy arm. The one exception here is larger side sleepers, who may find the subtle contouring comfortable.
❌ You want a classic memory foam feel: The Plank is all foam, but it certainly isn't a traditional memory foam feel. It lacks the sink-in comfort you might expect from an all-foam bed such as a Tempur-Pedic or Nectar Mattress.
❌ You're under 130lbs: Firmness is subjective and as a general rule, the lighter you are, the firmer a mattress feels. Particularly lightweight sleepers seeking a firm bed might prefer something with a little more give, such as the Puffy Cloud mattress.
The bottom line
The Plank Firm certainly lives up to its name, and the duality makes it a more versatile mattress than it may seem at first. Most side sleepers will want to avoid this one, as even the less firm side lacks any significant contouring. The absence of side handles is a questionable choice, given this bed's flippable design, but we otherwise find it a niche mattress that'll please a dedicated segment of sleepers.
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