Fort Building Kit: The All In One Soft Play Set That Actually Gets Used

Kids love forts. They are hideouts, castles, spaceships, secret bases, and so much more all in one afternoon. Building a fort encourages imaginative play and keeps kids busy for hours. Before foam blocks became mainstream, kids built forts from cardboard boxes, sofa cushions, blankets, sheets, and sticks, but those materials were unstable. The problem with most fort building kits is what happens after the fort comes down: pieces scatter into a closet, under the bed, into boxes nobody opens again. A real construction toy earns its place in your home by doing more than just forts. This guide walks you through what makes a great fort building kit, how to choose the right size, how to build your first few forts, and how RIWI® Giant Building Blocks become a tool for active play that does not sit idle after construction is done. For the wider category, check out our main guide to foam block sets.

Key Takeaways

A fort building kit is more than just soft blocks. Three things separate a kit that ends up ignored from one your kids build with constantly and opens up their imagination.

First: The blocks themselves. A real fort kit uses blocks big enough to feel like real building, not a toddler toy. Standard foam blocks measure somewhere between 12 inches and 18 inches per side. XXL foam blocks measure 28 inches long by 8 inches wide by 4 inches tall, which sounds like overkill until you stack them and realize one child can carry them alone, arrange them into real walls, and not worry about them toppling from a sneeze. The size difference is not just bigger looks, it is the difference between a floor-level hideout and an actual fort kids want to return to. These awesome, durable blocks let kids imagine and create in ways smaller construction toys simply cannot.

Second: The grip. Foam blocks that slide on each other collapse constantly. A high friction surface is what separates a fort that holds up during play from one that slides apart the moment a kid leans against it. The best fort blocks connect securely via a high friction surface so they grip each other without needing velcro, magnets, or connectors. They are pretty sturdy even under active play. Watch a child climb on a fort, lean against a wall, or rearrange blocks mid-play, and that grip is all that prevents the whole thing from sliding sideways.

Third: What happens when you are done playing. A fort kit that takes 30 minutes to break down and stuff into bags gets broken down once a month. A kit that stacks flat or transforms into seating gets reset every day. A 2-in-1 play couch and storage kit lets you fold a 24-block fort into a couch that lives in your playroom year-round. Not in a closet. Not in boxes. Visible, accessible, ready for the next build.

Fort building kits come in different sizes, and size matters more than most parents realize.

12 blocks is the gateway set and the perfect beginning for new builders. It builds a small hideout, a low tunnel, or a two-step climbing course. For one child in a small room or an apartment, 12 blocks is enough to understand whether your family loves fort building or tolerates it. 12 blocks also fit into a storage bag for easy carrying and are a great addition to any playroom.

24 blocks is the sweet spot for family fort building and offers so much fun for kids of varying ages. 24 blocks build a proper bedroom-sized fort, a house, or a cave with a front entrance and inside standing room. They build side-by-side hideouts for two friends. They build a climbing obstacle course with ramps and platforms. Most families with more than one child and a standard playroom find 24 blocks hit the right balance between building possibilities and storage reality. This is the size that fits into the play couch frame, so when fort time is over, the whole set becomes living room furniture.

36 blocks opens up three-room layouts, taller towers, multi-level designs, and structures like a treehouse or tent fortress. At this size, forts become more ambitious, and kids start thinking in 3D structure and science principles rather than just stacking blocks. A 36-block set suits families with a dedicated playroom, kids aged 5 and up, or siblings who like building together. You can still stack everything, but storage is now a meaningful decision.

48 blocks is the full-size playground and the ultimate creative canvas. 48 blocks build a real indoor fortress, obstacle courses with multiple sections, massive towers, a house with multiple rooms, or a fortress that connects to an igloo build. At this point, you are building things that rival backyard play structures in ambition. 48 blocks need dedicated space and usually live permanently in a playroom rather than being broken down and stored daily.

A practical rule: measure your intended building space in feet. A 6-by-8-foot room suits 12 or 24 blocks. An 8-by-10-foot room or larger suits 36 to 48. Do not choose by bedrooms; choose by actual play space. A 12-block set in an empty garage opens up possibilities a 48-block set in a cramped corner never will.

RIWI® Giant Building Blocks are the original giant foam block system, now in use across over 85,000 households and hundreds of schools, daycares, and therapy centers. The kit includes blocks in equal distribution of blue, yellow, green, and red, made from ActiveCore™ Foam, a non-toxic polyurethane foam designed for kid safety without being fragile. The brand has assembled and deployed over 2 million foam blocks in the field since 2017, and forts are among the most popular builds. For a broader look at soft play equipment for home and facilities, the blocks fit into setups well beyond forts alone.

Here is what you get in each set: blocks in equal distribution of blue, yellow, green, and red, made from ActiveCore™ Foam, a non-toxic polyurethane foam designed for kid safety without being fragile. Each block weighs roughly 2 pounds, so a 24-block set weighs about 48 pounds total, heavy enough to feel substantial but light enough for a 5-year-old to carry several pieces across the room alone. These durable, sturdy blocks encourage imaginative play from the beginning.

The blocks arrive compressed in boxes with assembly not required. Over the next 24 to 48 hours, they expand to their full size as air re-enters the foam. This compression also means a 36-block set fits in a box roughly the size of a large suitcase. There are also covers in velours (for extra grip and coziness) and wipeable faux leather (for outdoor and institutional use), though the bare foam blocks work perfectly well without them.

The high friction surface of RIWI® blocks is the detail most people overlook and then obsess about once they start building. Blocks hold their grip on each other and on finished floors without sliding. On carpet, the grip is even stronger. This is the difference between a fort that feels wobbly and one that is stable enough for an adult to sit inside. A parent climbing into a child's fort is not just fun; it is proof the blocks actually hold their promise of 242 lbs (110 kg) per block.

The beauty of fort building with these blocks is that there is no single right way. If you want more detail than the quick version below, our step by step foam fort build guide breaks down each stage. Here are three foundational designs that work with a 24-block set and take 10 to 20 minutes each to assemble. Whether you imagine a simple tent, a house, or an igloo, the blocks help you bring your ideas to life.

Step 1: Lay four blocks side by side on the floor, all facing the same direction. This is your base, roughly 28 feet long and 8 inches wide. Oops, no, not 28 feet. 28 inches, so just under 3 feet.

Step 2: Stack a second layer on top of the first four blocks. Now you have a wall about 8 inches tall and 3 feet long.

Step 3: Leave a gap of one block width in the middle of the wall. This is your entrance.

Step 4: Stack a third layer on top of the second layer, bridging across the entrance gap. You have just built a tunnel fort. Kids crawl in, play inside, and can see out the front opening.

This fort uses 12 blocks and takes 10 minutes. Younger kids (ages 3 to 5) love it. Older kids use it as a starting point and then add complexity.

Step 1: Follow the Simple Entry Fort steps 1 through 4.

Step 2: Build a second identical tunnel section parallel to the first one, leaving a 1-block gap between them.

Step 3: Stack a few blocks on top of that gap to create a roof bridge between the two tunnels.

Step 4: Add a second entrance on the far side of one tunnel.

You now have a fort with two rooms and two entrances. Kids can run through one entrance and out the other, or settle into separate rooms. This fort uses roughly 20 blocks and introduces the concept of multi-room builds.

Step 1: Arrange four blocks in a square on the ground.

Step 2: Stack a second layer of four blocks directly on top, aligned with the first layer.

Step 3: Repeat until you have a stack that is 4 or 5 layers tall, roughly 16 to 20 inches high. As you assemble, your blocks connect securely with each layer.

Step 4: The top platform becomes a lookout. Kids climb into the tower, stand on top of the top block, and survey their kingdom like they are in a treehouse.

A tower build with 12 to 16 blocks is a fast way to practice stacking skills and introduces height. Older kids love towers because they feel like real climbing and offer a ton of adventure possibilities.

The entire point of these three plans is not that they are the only right way to build forts but that you can teach your kids the logic in 30 minutes and then let them invent dozens more. Fort building is open-ended play, which is why it holds kids' attention so much longer than toys with a single purpose.

Here is where these sets separate from single-purpose toys. The same blocks that built a fort on Tuesday become five other things by the end of the week. This creativity and versatility is awesome.

Obstacle courses are the next-level build and encourage imaginative play at a higher skill level. Stack three or four blocks into platforms at different heights, arrange them with 2-3 foot gaps, and now kids are jumping from platform to platform, ducking under block-wide roofs, or crawling under ramps. Obstacle courses teach spatial awareness, balance, problem-solving, and science concepts in ways a closed fort simply cannot. A 36-block set gives you enough material to build an obstacle course on one side of the room while a fort still stands on the other.

Climbing platforms are essentially gentler obstacle courses. Stack blocks into a series of progressively taller platforms and now younger kids (ages 3 to 5) practice climbing and confidence. Parents can place blocks in a simple line and watch a toddler master the progression from one-block height to two-block height to three-block height over weeks.

Ball pits use the block walls as a container. Arrange blocks into a rectangular frame, drop plastic balls inside, and your fort blocks have become a DIY ball pit. The soft walls mean kids can tumble safely even if they lose their footing under the balls.

Seating emerges naturally once kids realize they can sit on stacked blocks. Reading nooks, outdoor seating for older kids, or just places to rest between play sessions, even winter and summer play transitions. This is especially true if you have opted for velours covers, which add a cozy texture. Kids can create chairs with small parts stacked intentionally.

Storage furniture brings us back to the Play Couch idea. A 24-block set collapses into a couch-like shape via the play couch frame, turning 48 pounds of foam into functional living room furniture that stores blocks inside. The couch angle is not a gimmick; it is why families keep their sets out instead of hiding them in closets.

This versatility is the reason these sets remain popular from ages 3 to 12. Toddlers stack and climb. Preschoolers build simple forts. School-age kids build obstacle courses and multi-room complexes. Tweens engineer increasingly ambitious structures. One kit grows with your child.

The single most important purchase decision for a fort kit is not the block set itself but the storage solution. Here is why: if your blocks are packed away after every build, they get built maybe once a month. If your blocks live as accessible furniture, they get built three to five times a week.

The RIWI® 2-in-1 Play Couch & Storage Kit solves this problem directly. It is a frame that lets 24 blocks fold into a couch shape. On Monday your blocks are a fort. Tuesday they are a tower. Wednesday your kids have left them stacked as a couch with the blocks exposed, and your living room now has a conversation piece. Thursday they are rebuilt into something new. The couch lives visible in the family room all week because it actually looks intentional.

Contrast that to a storage bag or a closet: blocks hidden are blocks forgotten. The difference in play frequency between visible, accessible storage and closed-away storage is not small. Families report their kids build more often, experiment more, and stay engaged longer when blocks are treated as furniture rather than hidden toys.

If you do not have space for a play couch, a storage bag works fine for 12 blocks, and a regular shelf or low cabinet works for any size if you commit to keeping blocks visible. The key is the same: accessible storage wins every time.

A few guidelines help fort building remain safe, fun, and something your family actually returns to.

Supervision by age. Kids under 5 building forts should have a parent or older sibling watching. By age 5 to 6, kids who have built forts before can build alone with periodic check-ins. The biggest risks are not the foam (which is soft) but the structural integrity of taller builds and kids overestimating their climbing abilities.

Start simple, build confidence. Teach your child one fort design well before moving to three. Kids who successfully build the Simple Entry Fort five times understand the logic and confidence to invent their own. Kids who are always given instructions stay dependent on an adult. Beginning with one design teaches crucial assembly and problem-solving skills.

Leave the fort up longer. Kids play inside forts much longer than kids play in open spaces. A fort that lives for three days (with play throughout) generates more than three days of value. A fort that is rebuilt daily teaches structure and creativity.

Combine sets if you can. If a 24-block set is your baseline, adding a second 24-block set (or a 12-block set) doubles your building possibilities without doubling your footprint once combined. Many families start small and add a second set as kids get older and more ambitious.

Mix in other toys strategically. Stuffed animals, blankets, balls, toy vehicles, and books inside forts make them more interesting and encourage imaginative play. You can even drape sheets over poles you rest on the blocks, use pillows to create more cushioning, or add toy sticks and props. A fort filled with nothing is cooler in concept than in practice; a fort that becomes a stuffed animal sanctuary or a reading nook keeps kids engaged longer. For more inspiration on a rainy afternoon, see our ten rainy day fort ideas.

Deciding on set size depends on three questions.

First: How much floor space do you actually have? Be honest. A 24-block set needs a 6-by-8-foot space to build a comfortable fort. A 36-block set needs a bit more. If your playroom is smaller, start with 12 or 24 blocks rather than buy a 48-block set that lives half-built all the time.

Second: How many kids are building together? One child happily spends an afternoon with 12 blocks. Two friends need 24 to avoid constant conflicts over who uses which pieces. Three kids or more, or kids with different play preferences, benefit from 36 blocks so multiple forts can exist simultaneously.

Third: How ambitious are your kids? Kids aged 3 to 5 are happy with Simple Entry Forts and towers. Kids aged 6 to 8 usually want multi-room complexity, like a house or a tent design. Kids aged 9 to 12 start thinking in obstacle courses, engineering challenges, and more pieces for increasingly complex builds. Match set size to your kids' current building ambitions, not their age alone.

Here is a practical recommendation: start with a 24-block RIWI® set. It is the most versatile, builds proper forts and so much more, is a great addition to any home, and gives your family six months to a year of active play before you know whether a second set is worth the investment.

The blocks hold up to 242 lbs per block, so the limits are structural, not material. A three-block tower is safe for kids to climb. A four-block tower is pushing it unless the base is wide and the stacking is perfect. A five-block free-standing tower is risky without an adult spotting. The best rule: if you would not want your child falling from that height onto soft foam, it is probably too tall.

Not solo. The blocks are rated for ages 3 and up, and there is a reason. Toddlers under 3 can hurt themselves by stacking blocks and pulling them down, or getting small parts pinched in a collapse. With close supervision and simple, very low structures (one or two blocks tall), some 2-year-olds enjoy the sensory experience of moving foam. But independent play starts at age 3.

Not really, which is why these foam blocks end up in schools and therapy centers. The ActiveCore™ Foam does not trap dirt the way some foam does. A vacuum pass over the blocks weekly if they are getting heavy use, and a gentle spot-clean with a damp cloth if something spills on them, is enough. If your blocks have removable covers (Velours or Faux Leather), wash those every few months in cold water on a gentle cycle.

This is rare but possible if blocks are stored in extreme heat or weight for months. In the unlikely event a block does not re-expand to full size after 48 hours at room temperature, contact customer support. Most blocks re-expand fine, and the company stands behind the product.

Yes, but they will not perform the same. Cheap foam block sets have poor grip, slide around, and collapse easily. Mixing high friction blocks with lower-quality foam is like adding low-quality bricks to a wall, it works but undermines the whole structure. If you are adding more pieces, invest in another set of the same system so the high friction surface, sturdy assembly, and durability are consistent.