You need a box spring only when nothing else under the bed can hold the mattress up, so I'd look at the frame first. A mattress on a plain metal frame, or on a panel bed with bare side rails, needs a box spring or a flat foundation. On a platform bed, a sound slatted base or an adjustable base, it doesn't.
A box spring is a fabric-covered wooden frame filled with coils or a flexing steel grid. It sits under a mattress to hold it flat and lift it off the bed frame. The mattress warranty matters too, because the maker decides what counts as proper support. Restwell and Restonic both put conditions on queen and king beds, and both ask for a new foundation with a new mattress.
At Merit Home Furniture, 20 mattresses are listed for our Duncan store: 10 Restonic, 8 Restwell and 2 from Natura. Below are the Restwell and Restonic support rules and the bases Merit lists for Duncan on Vancouver Island. The last part covers what a tall mattress does to the height of a bed.
Do I need a box spring? Five ways to hold up a mattress
Five kinds of base can go under a mattress, and only one is a true box spring. A mattress needs one of them, plus whatever frame lifts it off the floor.
| Base | What it is, and what it suits |
|---|---|
| Box spring | Coils or a flexing steel grid in a wood frame, under fabric. It gives a little, and it was built for coil mattresses on a metal frame or rails. |
| Foundation | The same box shape with a rigid deck of wood slats or a solid panel. The usual partner for foam and hybrid beds now. |
| Slatted base | Wood slats laid across a bed frame's rails. It can carry a mattress alone if the slats are close and the middle is held up. |
| Platform bed | A bed frame with its own deck of slats or panels. No box spring goes on it. |
| Adjustable base | A powered deck whose head and foot lift. It takes the place of a box spring entirely. |
Sleep Foundation's guide to box springs draws the line by mattress type. Innerspring mattresses are often designed for a box spring, it says, while all-foam beds are not. Foam needs rigid support and can be damaged, or wear out sooner, on a base that gives. It puts many latex and hybrid beds in the same group and suggests checking the warranty when unsure.
What a box spring is made of, and how it differs from a foundation
A box spring has three parts: a wooden or metal frame, coils or a steel grid inside it, and a fabric cover. The springs take up some of the movement when you lie down or turn over, which Sleep Foundation says softens the impact and can extend the life of the mattress. They also spread your weight onto the frame below.
A foundation looks the same from the outside but doesn't give. Tempur-Pedic Canada describes its own foundations as completely flat and solidly built, so the mattress does the supporting. In practice the two names overlap. Sealy's 9-inch foundation, carried at our Campbell River store, is Canadian spruce over a steel semi-flex grid with a centre support. Tempur-Pedic's 5-inch flat foundation at the same store is a solid, flat fibre panel.
Why are box springs no longer used?
Box springs are still made, but fewer beds call for one. Sleep Foundation notes they were much more common years ago. The change followed the mattresses: foam, latex and hybrid beds want a deck that stays flat, and a true spring base moves under them. Sleep Foundation also lists a box spring as too rigid to work with an adjustable bed frame, which leaves it out of that setup as well.
Do I need a box spring for a mattress from Restwell or Restonic? The warranty terms
For a Restwell or Restonic mattress, the support underneath is written into the warranty. Restwell, a mattress maker based in Surrey, sets its rules out in a 2024 warranty brochure. Restonic's Canadian address, restonic.ca, is a parked page with no warranty text. The Restonic terms here come from the warranty card and FAQ on restonic.com, its US site. That card says the warranty comes from the Restonic maker named on the law label, so the tag on your own mattress has the final word. We couldn't find Natura's support terms published online, so the table covers the other two; ask us before a Natura bed goes onto slats or rails.
| Term | Restwell | Restonic |
|---|---|---|
| Queen and king | Covered only on a frame with a rigid centre support | Frame or bed base with centre support, to keep the warranty valid |
| Headboard and footboard beds | No less than five hardwood slats and at least 5 legs, evenly spaced, the end slats no more than 3 inches from the headboard or footboard | No slat count on the card |
| Not covered | Mattress damage from an inappropriate foundation | Damage from an inappropriate foundation, bed base or incorrect frame |
| With a new mattress | Replace the foundation too | Replace the foundation too |
| Body impressions treated as normal | Up to 1 1/2 inches | Under 0.75 inch, or 1.5 inches on a quilt top |
| Adjustable base | Not mentioned in the brochure | All Restonic mattresses can be used with one |
Restwell also tells buyers not to slide a board between the mattress and the foundation, since the set is designed to give the support on its own. Its brochure explains why the old base matters. A new mattress can look as if it's sagging when the foundation under it is what has given out.
Neither document holds twin or double beds to the centre-support rule. The beds carried at our Campbell River store follow their own makers' terms. Sealy Canada asks for extra centre support under any queen or king set to prevent bowing. Tempur-Pedic Canada accepts a structurally sound slatted platform, as a general rule with slats 3 inches wide and no more than 4 inches apart. When a claim does come up, Merit backs the maker's warranty, orders the parts and handles the repair.
Do I need a box spring with a platform bed?
A platform bed doesn't take a box spring. It's a bed frame with its own deck of slats or panels, and the mattress lies straight on top. Ashley's listings for the Finch and the Cabinella both say the bed doesn't require a foundation or box spring. Seven beds in Merit's platform beds collection are listed for our Duncan store. The table takes four of them, plus a Mako storage base that does the same job.
| Listed for Duncan | Deck, height and price |
|---|---|
| Ashley Finch queen platform bed | Engineered wood, 16 inches high, $189.00 |
| Ashley Cabinella platform bed | Full or queen, 16 inches high, $299.00 to $353.00 |
| Mako Claudette platform bed | Solid pine, headboard, footboard, rails and slats, $849.00 to $1,099.00 |
| Primo Air Flow king platform base | Three wood panels on a steel frame, legs at 4, 8 or 12 inches, rated up to 770 lbs, $599.00 |
| Mako Belmont lift-top storage base | Solid wood, 15 inches high, the deck lifts for storage, $1,349.00 to $1,649.00 |
Prices are as listed, before applicable taxes. The Primo's legs also come off, and its listing says it then works as a low foundation inside an existing frame.
Do I need a box spring if I have slats?
Slats can carry a mattress alone when there are enough of them and the middle of the bed is held up. Restwell's minimum for a queen or king is five hardwood slats, 5 legs and a centre support. Tempur-Pedic is stricter on the gaps, at 4 inches or less. Mako's listings say each bed arrives with rails and slats but don't print the slat count. Before a Mako bed goes under a Restwell queen, that count is worth asking us about.
Do I need a box spring with a bed frame? Panel beds and metal frames
A panel or sleigh bed with only side rails needs a box spring or foundation on those rails, and the listing usually says so. Ashley's Baystorm, Juararo and Alisdair listings each read "Foundation/box spring required".
A plain metal frame, the kind often called a Hollywood frame, has no deck of its own either. With a metal frame, a box spring or foundation is part of the bed. The Beaudoin 961G, which our Duncan and Port Alberni stores carry, fits a full or queen box spring. Its listing gives one centre support, 6 plastic glides and a rating of 650 lb, at a height of 7.125 inches.
What goes on top of that frame is the open question on our Duncan list. None of the bases on Merit's site is a Restwell or Restonic box spring or flat foundation. If a Restwell, Restonic or Natura bed is going onto rails or a metal frame, a call to the Duncan store before ordering settles what goes under it.
Sealy, Tempur-Pedic, Serta and Beautyrest foundations are carried at our Campbell River store, the Beautyrest 9-inch at Port Alberni too, with no online price. A call there gets our best price. The outside size of every frame type, metal or platform, is laid out in a size-by-size table of bed frame footprints.
Low-profile foundations and box springs for tall mattresses
A low-profile foundation is a shorter foundation, usually 5 inches instead of 9, made so a tall mattress doesn't push the bed too high. The mattresses listed for Duncan run from 11 inches, the Natura Majestic, to 16 inches, the Restonic Vernazza and Treviso. Several Restwell beds, the Canary among them, sit at 12 inches. Put a tall one on a 9-inch foundation and a frame, and the top of the bed climbs quickly.
The table adds the listed heights on the Beaudoin 961G frame, as rough figures.
| Mattress | On a 9-inch foundation | On a 5-inch foundation |
|---|---|---|
| Restwell Canary, 12 in | About 28 inches | About 24 inches |
| Restonic Vernazza, 16 in | About 32 inches | About 28 inches |
Sealy Canada says its low profile box spring can take as much as 4.5 inches off the box spring's height, and a low-rise frame lowers the bed further. Restonic's FAQ offers the same fix for a mattress that sits too high: a new foundation that suits it better.
Height is partly comfort. Sleep Foundation notes that some people find a raised bed easier to get in and out of.
Adjustable bases in place of a box spring
An adjustable base replaces the box spring outright. It's a powered deck whose head and foot sections lift, and the mattress goes straight onto it. Restonic's FAQ says all Restonic mattresses can be used with one. Among the Restwell beds Merit lists for Duncan, only the Savannah Plush listing calls itself adjustable base friendly, so ask us about the others.
Several powered bases listed for Duncan carry a price. The Restwell Peak is $999.00 to $1,099.00 and comes with legs of 1, 3 or 6 inches. The Restwell Pinnacle, with massage and presets, is $1,499.00 to $1,849.00. Ashley's head-only queen power base is $764.00, and its head-and-foot queen with massage is $1,561.00. Prices are before applicable taxes.
Weight ratings, warranties and the frames that take a base are compared in what each adjustable base carries and costs. Every powered base we list is in the adjustable bases collection.
Do I need a new box spring with my mattress? Lifespan and the old one
Restwell and Restonic, two of the three mattress makers listed for Duncan, both say a new mattress gets a new foundation. Each lists it among the do's on its warranty papers. Sealy Canada goes further and calls a good box spring as important as a good mattress, because it takes much of the nightly wear.
How long do box springs last?
Restwell and Restonic tie a box spring's life to the mattress on it. Sleep Foundation says bed springs often need replacing every 10 years, and suggests replacing the box spring along with a mattress that wears out sooner. Condition counts for more than the date. A dip you can see with the mattress off, a cracked slat or a broken corner means the base is done.
Signs that the mattress itself is finished, and the usual lifespan of each type, are in Merit's guide to the signs a mattress has worn out. For whether a foam or hybrid bed suits you in the first place, there's how foam, hybrid and coil beds compare.
The old box spring has to go somewhere. When we deliver from Duncan, old furniture can be taken away at the same visit, usually for $25 to $50 a piece. In the Cowichan Valley, the regional district charges $32 per unit for a mattress or box spring at its recycling facilities, with a surcharge for soiled ones. For a bigger clear-out, the spring cleaning jobs for every room include the depot run.
When the box spring or base causes the sagging
A mattress that sags after only a few months often has a base problem, so the base is worth checking first. Restwell's brochure makes that point about old foundations. Its service form asks how many legs the frame has, and whether they're fixed to cross slats or a centre bar. These setups cause the most trouble:
- A foam or hybrid bed on a sprung box spring. Sleep Foundation says foam can wear out faster on a base that gives.
- Plywood laid over a box spring. Tempur-Pedic Canada says it makes an unstable surface and voids its warranty, and Restwell says no board between mattress and foundation.
- An old base kept under a new mattress, which Restwell and Restonic both advise against.
- The bare floor. Sleep Foundation says nearly all mattresses do better with support under them than lying directly on the floor.
Checking the box spring or slats you already have
Checking an existing bed base takes a tape measure and a few minutes, using the Restwell and Tempur-Pedic terms above.
- Take the mattress off. Look at the bare foundation or slats in daylight. It's also the moment for a quick look for bed bugs in the seams and corners.
- Lay a straight edge across it. A long level or a broom handle shows a dip in the base before it shows in a new mattress.
- Count the slats and legs. For a Restwell queen or king, that means at least five hardwood slats, at least 5 legs and a centre support.
- Measure the widest gap. Tempur-Pedic's limit is 4 inches between slats.
- Press for squeaks. Restwell's form suggests pushing down on the frame in several places to find a noise before blaming the mattress.
- Read the law tag. The warranty code on the mattress tag tells you which terms apply to that bed.
If you're keeping a bed frame, I'd rather see a photo of it with the mattress off, slats and legs showing, than guess. Bring that and the frame's inside measurements, and we can work out together whether it needs a foundation, a platform base or nothing at all.
Sources for the box spring and warranty figures
- Restwell Sleep Products, Warranty and Mattress Care brochure 2024 (frames, slats, foundations, impressions), checked November 2026.
- Restwell Sleep Products, warranty service form (frame legs, centre bar, noise check), checked November 2026.
- Restonic (US site), Restonic Warranty card, checked November 2026.
- Restonic (US site), FAQ on foundations, bed height and adjustable bases, checked November 2026.
- Tempur-Pedic Canada, Frequently Asked Questions (foundations and platforms), checked November 2026.
- Sealy Canada, FAQs (box springs, low profile box springs, frame support), checked November 2026.
- Sleep Foundation, Do You Need a Box Spring? (Logan Foley, updated July 15, 2025), checked November 2026.
- Cowichan Valley Regional District, Accepted Materials and Fees (mattresses), checked November 2026.
- Merit Home Furniture's live mattress, foundation, bed frame, platform bed and adjustable base listings, and the Duncan store's delivery terms, read November 1, 2026.
Asking our Duncan store about a box spring or base
The Duncan store is at 107 Ingram Street, open 9 to 5, Monday to Saturday. The Restwell, Restonic and Natura mattresses, platform beds and adjustable bases above are listed for Duncan. Ask which ones are set up as display models before you make the trip. Nobody at Merit will trail you around the showroom, and going home to measure the old frame first is fine.
Delivery from Duncan is $150 across the Island with setup and assembly, and pickup at Duncan is free. Delivery to some Gulf Islands can be arranged, so call the store for details. A mattress going a long way across the Island may need a different shipping method. Campbell River, (250) 286-0868, and Port Alberni, (250) 724-6644, set their own delivery terms.
Call the Duncan store, (250) 746-5527
For more on choosing and caring for a mattress, start with the rest of our mattress buying and care guides. Every box spring and foundation we list sits in the box springs and foundations collection, and the platform frames in our platform beds.