Ultra Low-Profile Mattress Foundation – 1.5" Organic Wood Bunkie Board

From : $160.00 - $290.00

A 1.5" solid-wood low-profile mattress foundation that drops in where a box spring used to go - without raising your bed an inch. GOTS-certified organic cotton cover, no chemical fire retardants, no off-gassing. Compatible with any mattress (hybrid, latex, memory foam, innerspring) on platform beds, bunks, or standard frames. Height: 1.5" • Slats: 2.5"W × 5/8"H, 3" spacing.

Size

Twin
Twin XL / Split King
Full
Queen
King
Cal King
Split Cal King

Quantity:

Description

What This Foundation Does

The SLEEP365 Ultra Low-Profile Foundation (also called a bunkie board) is a 1.5" solid-wood platform that provides flat, even, mattress-warranty-safe support without adding the 5–9 inches a traditional box spring brings to your bed height. Use it as a complete replacement for a box spring on a standard bed frame, as a stabilizer over slats that are too widely spaced, on a bunk bed, or directly on a platform bed that needs a smoother support surface.

Constructed from solid North American kiln-dried lumber and wrapped in a GOTS-certified organic cotton cover, it contains no toxic fire retardants and no chemical adhesives, so there is no off-gassing in your bedroom.

The Queen has one center support rail; King and Cal King include two center rails for extra rigidity. Modular design assembles in under 15 minutes with a flat-head screwdriver.

Low-Profile Foundation vs. Traditional Box Spring

	SLEEP365 Ultra Low-Profile Foundation	Traditional Box Spring
Height	1.5"	5"-9"
Construction	Solid kiln-dried wood slats, 3" spacing	Steel coils inside a wood frame
Cover	GOTS-certified organic cotton, no flame retardants	Synthetic ticking, typically treated with chemical fire retardants
Off-gassing	None	Common
Mattress compatibility	Hybrid, latex, memory foam, innerspring	Mostly innerspring only - voids warranty on most foam/hybrid/latex mattresses
Use on a platform bed	Yes, recommended	No, too tall, defeats the purpose
Use on a bunk bed	Yes	No, too tall and heavy
Center support	Yes (1 rail on Queen, 2 on King/Cal King)	Yes
Lifespan	10+ years	5–8 years (coils break down)
Warranty	10-year non-prorated	Typically 1–5 years

Choose the Ultra Low-Profile Foundation if: you have a platform bed, a bunk, or a frame where a box spring would push your mattress too high; you have a foam, latex, or hybrid mattress whose warranty requires a solid or closely-slatted base; or you want an organic, non-toxic alternative to a chemical-treated box spring.

Choose a taller foundation instead if: you're replacing a worn-out box spring on a traditional bed frame and want to keep your bed at its current height. In that case see our 5" Wood Slat Foundation or 8" version.

What's Included

Side rails (2)
End rails (2)
Center support rail (1 on Queen, 2 on King / Cal King)
Pre-attached slat rolls with hook-and-loop fastening
Flat-head screws
Assembly instructions
Required tool: flat-head screwdriver (not included)

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Measurements

Size Measurements

Twin
Width: 37.5"
Length: 74.5"
Height: 1.5"

Twin XL / Split King
Width: 37.5"
Length: 79.5"
Height: 1.5"

Full
Width: 52.5"
Length: 74.5"
Height: 1.5"

Queen
Width: 59.5"
Length: 79.5"
Height: 1.5"

King
Width: 75.5"
Length: 79.5"
Height: 1.5"

Cal King
Width: 71.5"
Length: 83.5"
Height: 1.5"

Split Cal King
Width: 35.5" x 2
Length: 83.5"
Height: 1.5"

Slat specifications: 2.5" wide x 5/8" thick, spaced 3" apart - meets the warranty requirements of all major foam, latex, and hybrid mattress brands including Naturepedic, Vispring, Tempur-Pedic, Avocado, and Saatva.

Materials: Solid North American kiln-dried hardwood frame; GOTS-certified organic cotton cover; no chemical fire retardants; no formaldehyde-based glues.

Center support: Queen ships with one center support rail. King and Cal King ship with two center rails.

Shipping: Ships flat in a single box. Assembled dimensions match the table above. All measurements are approximate (+-0.5").

Important: If ordering Split Cal King, two pieces are required to complete one Cal King mattress base. If ordering Split King, two Twin XL pieces are required to complete one King base.

Quality Promise & Warranty

10-Year Limited Warranty

The Ultra Low-Profile Foundation is covered by a 10-year non-prorated limited warranty against defects in materials and workmanship, three to five times longer than a typical box spring warranty. The warranty covers:

- Broken or cracked slats under normal use
- Frame separation or rail failure
- Defects in the organic cotton cover (seams, weave, fastening)

The warranty does not cover damage from improper assembly, exceeding the weight capacity, exposure to moisture, or normal cosmetic wear.

Certifications & Materials Promise

- GOTS-Certified organic cotton cover (Global Organic Textile Standard) - the strictest organic textile standard in the world
- No chemical fire retardants (we use a thin wool barrier where required by federal law, never PBDEs or chlorinated tris)
- No formaldehyde-based adhesives
- No off-gassing - safe to use the day it arrives
- Solid North American kiln-dried lumber - sustainably sourced, no MDF or particleboard
- CARB-2 compliant

Returns

Foundations are a final-sale item, no refunds or exchanges. This is industry standard for foundations and bunkie boards (they cannot be sanitarily resold once opened). If you receive a defective unit, contact us within 30 days for a warranty replacement.

Need help deciding what size to order?

Call us at (800) 270-3559 or visit one of our Bay Area showrooms - Burlingame, Marin, San Francisco, or Silicon Valley.

GOTS Certified

Global Organic Textile Standard Certification

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Your bed should be a place to rest, recover, and rejuvenate with the perfect balance of comfort and support for your body and mind.

Optimize Your Support

The SLEEP365® Foundation collection offers heavy-duty wood slat foundation options designed for those seeking the ideal bed height and strong, non-toxic support for their bed.

Strong & Clean

Solid North American, kiln-dried lumber and GOTS certified organic cotton fabric cover — no toxic fire retardants, no off-gassing.

Which Support Base is Right for Me?

Our versatile selection of support base options offers you strength & stability, form & function, ergonomics & aesthetics for the ideal sleep system.

Wood Slat Foundation

Craft the perfect bedroom with your ideal bed height and sturdy, non-toxic support with the SLEEP365® Foundation made with North American lumber and GOTS certified organic cotton fabric.

Options

1.5” - Ultra-low profile suitable for platform beds.
5” - Low-Profile Design made for bed frames that require a shorter height.
8” - Traditional Height Foundation suitable for various types of bed frames.
Optional 5" or 7" legs (set of 9) to use with 8" and 5" foundations creates a complete support system without the need for a bed frame.

Shop Wood Slat Foundations

Platform Bed

Discover modern simplicity and ease-of-use with our solid wood platform beds, designed to provide strong, durable support and enhance the natural appeal of your bedroom

Features

Easy Assembly
Contemporary, minimalist design
Non-toxic, natural teak oil finish
Solid walnut, cherry, maple or oak
Available with or without a headboard

SHOP PLATFORM BEDS

Adjustable Base

Personalize your sleep and lifestyle with the flexible features of our Adjustable Bases Collection. Each base offers positional versatility with user-friendly controls. Customize your bed for entertainment, work, relaxation and sleep with unique positions that align to your body type and comfort preferences as you see fit.

Standard

Basic functionality
One-touch flat, zero-gravity, anti-snore

Premium

Enhanced functionality
Massage, under-bed light

Luxury

Robust functionality
Lumbar support with massage, wall-hugger movement

SHOP ADJUSTABLE BASES

Which Foundation is Right for Me?

8-inch Wood Slat Foundation

TALL

The 8" Wood Slat Foundation matches the footprint of a traditional box spring, so it drops into almost any standard bed frame without changing the overall bed height your room is built around. It is the right pick if you are replacing a worn-out box spring on an existing frame, or if you are buying your first organic mattress and want the bed to feel familiar rather than significantly lower than what you slept on before.

Solid North American kiln-dried lumber with a center support rail
2.5"-wide slats spaced 3" apart for warranty-safe support of hybrid, latex, memory foam, and innerspring mattresses
GOTS-certified organic cotton fabric cover, no off-gassing, no chemical fire retardants
Tool-free, modular assembly (under 15 minutes)
Available in Twin through Split Cal King
Pairs with optional 5" or 7" rubberwood legs to use as a freestanding base without a bed frame

5-inch Wood Slat Foundation

MEDIUM

The 5" Wood Slat Foundation is the "just right" balance for sleepers who find a standard 8" foundation pushes the top of the mattress too high, particularly with a thicker hybrid or latex mattress on top, or in a low-profile bedroom where the bed is meant to sit closer to the floor. It carries the same wood, cover, and slat spacing as the 8" version; only the height changes.

Same 2.5"-wide slats spaced 3" apart, supports hybrid, latex, memory foam, and innerspring mattresses without voiding mattress warranties
Solid North American kiln-dried lumber with center support rail
GOTS-certified organic cotton fabric cover
Tool-free, modular assembly
Available in Twin through Split Cal King
Pairs with optional 5" or 7" rubberwood legs to function as a complete freestanding base, or sits inside a low-profile bed frame

1.5-inch Ultra Low-Profile Foundation

LOW / BUNKIE BOARD

The 1.5" Ultra Low-Profile Foundation is the pristine picture of low-profile perfection for the modern bedroom.

Increases support without adding excessive height
Solid North American lumber
Organic cotton fabric cover for breathability

Natural Rubberwood Foundation Leg

OPTIONAL

Available for use with our 8" and 5" wood slat foundations, our optional legs give you the lift you need without requiring a typical metal frame.

Available in 5" or 7" heights
Sturdy support without a bed frame
Eco-friendly, solid, unfinished rubberwood construction
Easy, tool-free installation
Set of 9

Frequently Asked Questions

Do I need a box spring or foundation if I have a platform bed?

Most platform beds have closely-spaced slats and don't require a separate foundation. However, if your platform bed has slats spaced more than 3" apart, or if the slats are wide enough to feel through the mattress, the Ultra Low-Profile Foundation gives you a flat, even support surface without adding much height. It also protects your mattress warranty, many manufacturers void warranties when slat spacing is too wide.

What's the difference between a bunkie board and a low-profile foundation?

The terms are used interchangeably. A "bunkie board" originally referred to the thin support board used on bunk beds. Our Ultra Low-Profile Foundation works the same way - a 1.5" tall solid platform that gives flat, even support without the height of a traditional box spring. We call ours a "foundation" because it's structurally sturdier than the typical fabric-covered MDF bunkie boards sold at big-box stores.

Will this work with my Tempur-Pedic, Avocado, Naturepedic, or Saatva mattress?

Yes. The 3" slat spacing on our foundation meets the warranty requirements for all major mattress brands including Tempur-Pedic, Avocado, Naturepedic, Saatva, Casper, Purple, Brooklyn Bedding, and Vispring. If you're unsure, check your mattress warranty document for the maximum slat spacing, anything 3" or less is safe to use.

Can I use the Ultra Low-Profile Foundation with an adjustable base?

No. Adjustable bases have their own integrated support surface. The Ultra Low-Profile Foundation is designed to either replace a box spring on a static frame or sit on top of a platform bed's slat surface. For adjustable bases see our Standard, Premium, and Luxury Adjustable Bases.

How is this different from a traditional box spring?

A traditional box spring is 5"–9" tall and contains steel coils inside a chemically-treated wood frame. The Ultra Low-Profile Foundation is 1.5" tall, has solid wood slats instead of coils (won't sag or squeak over time), and uses a GOTS-certified organic cotton cover with no chemical fire retardants. It's also rated for foam, latex, and hybrid mattresses, traditional box springs typically void those warranties.

How long does assembly take?

Most customers assemble a Queen in 10–15 minutes with a flat-head screwdriver. The rails snap into place with notched joints; the slat rolls attach to the rails with pre-attached hook-and-loop tape.

Is this organic, or just the cover?

The cotton cover is GOTS-certified organic. The wood frame is solid kiln-dried North American hardwood, there is no organic certification for wood lumber (no such certification standard exists), but the wood contains no formaldehyde-based glues, no MDF, no particleboard, and no chemical fire retardants.

Do I need two pieces for a King or Cal King?

The standard King and Cal King sizes ship as a single unit. The Split King is two Twin XL pieces (used for adjustable bases or couples with different preferences). The Split Cal King is two pieces that together equal a Cal King. Check your order carefully, split sizes are not refundable.

What if a slat breaks?

Covered under the 10-year warranty (assuming normal use within the weight capacity). Contact customer service at (800) 270-3559 with your order number and a photo; we ship replacement slats.