Pour Strip Zero

Pour Strip Zero Resources: Guides, Manuals, and Concrete Joint Explainers

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Recent Articles and Publications

Traditional Pour Strip below a PS=Ø Floor with no leave out.

STRUCTURE MAG - Pour Strips Often Overlooked and Misunderstood

For over 40 years, the traditional pour strip in concrete construction has been an issue of contention between the EOR and the Contractor, and this... read more

Construction Crew Pouring Concrete

Concrete International - Designing for Construction Productivity and Safety

Thanks to many outstanding software tools available today, structural engineers can efficiently and effectively design economical reinforced concrete... read more

PS=Ø Floor – Clean, no trench and no backshoring.

Concrete International - Designing for Construction Productivity and Safety

Since our first Concrete International article on gapless pour strips, engineers and contractors have become more creative with the PS=Ø... read more

MWR Conference Hotel Mayflower Resort

AGC of Utah - The Construction of MWR Conference Hotel at Mayflower Resort

Along the highway between Heber and Park City sits the first new ski resort to be developed in the United States in over 40 years.

Gaylord Pacific Resort

ENR West - $1.3B Gaylord Pacific Resort Rises Along San Diego's Bayfront

For more than 20 years, the Gaylord Pacific Hotel and Convention Center has been talked about in some fashion, in large part because of the incredible opportunity...read more

Guides & Manuals

Install Manual

Step-by-step installation guidance for the PS=Ø system on your project.

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Grouting Manual

Grouting procedures and best practices for a clean, continuous slab.

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Lunch & Learn

Book an educational session for your team on eliminating pour strips.

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Understanding Concrete Joints

Plain-language explainers on the leave-outs and joints PS=Ø is engineered to eliminate, from the pour strip in a post-tensioned deck to the broader family of movement joints.

Post-Tensioned Concrete Slabs

Why post-tensioned decks shorten more, and how the pour strip they rely on can come off the critical path.

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Closure Strips Explained

Why a closure strip is needed, the construction problem it creates, and how PS=Ø solves it. Full terminology and FAQ below.

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The Pour Stop Explained

What a pour stop is, how it differs from a pour strip, and how PS=Ø removes the leave-out behind it.

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Expansion Joints in Concrete

What expansion joints do, where they cost you, and how a continuous slab eliminates them.

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Concrete Movement Joints

The full family of movement joints and where the pour-strip leave-out fits among them.

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Reinforced Concrete Construction

Continuous reinforcement methods at the construction joint, and how a mechanical splice keeps the steel continuous without a pour strip.

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Closure Strip Technical Detail

Closure Strip Terminology, Sequencing & FAQ

The deep-dive companion to our simplified Closure Strips Explained page: the four names crews use for the same leave-out, why it traditionally sits open for weeks, the full PS=Ø installation sequence, and the engineering FAQ.

One leave-out, four names

Closure pour

Also called: closure strip, closure joint

The concrete placed later to close a gap that was left open on purpose. The leave-out itself, and the pour that fills it, both get called the closure pour.

Delay strip

Also called: delayed pour strip, pour strip

A strip of slab intentionally left out and cast later so the two sides can shrink first. The most common term for the same detail on cast-in-place structures.

Pour stop

Also called: pour break, day joint

Where the day's placement stops. On the field it becomes the closure line the crew comes back to fill once the adjacent concrete has done most of its shrinking.

Shrinkage strip

Also called: restraint-to-shortening strip

A closure strip named for its job: relieving restraint-to-shortening by letting the slabs on either side shorten before the strip is cast to lock them together.

Why the traditional strip sits open for weeks

Traditionally a closure strip stays open, commonly 30 to 60 days, so the adjacent slabs can shrink before they are tied together. Here is the traditional sequence against the PS=Ø sequence.

Stage Traditional closure pour / delay strip PS=Ø splice
At the joint Strip left out, reinforcement exposed in an open gap Couplers and closure strip set where the leave-out would sit
While the slab shrinks Weeks of waiting, gap open on the critical path Slab shortens naturally, off the critical path
Other trades Work around an open gap collecting debris Cross a self-supporting seam, no leave-out
Closing it Return trip to form and pour the closure strip Grout the couplers, seam is continuous

How PS=Ø eliminates the closure strip

  1. 1

    Engineered shop drawings

    Our engineers detail the splice into your structural design so it carries the reinforcement across the seam where a closure strip would otherwise interrupt it.

  2. 2

    Couplers set where the pour stop would sit

    The couplers and closure strip go in exactly where the leave-out would sit, so crews are not leaving an open gap and exposed rebar across the deck for the trades to work around.

  3. 3

    The slab shortens and cures naturally

    The concrete goes through its natural volume change off the critical path. No 30 to 60 day open strip, no waiting to keep the schedule moving.

  4. 4

    Grout the couplers to close the seam

    Once shrinkage is complete, the couplers are grouted to finish a continuous, ICC Approved, ACI 318 Type 1 and Type 2 compliant connection. The closure strip is gone.

End view of a PS=Ø mechanical rebar coupler that replaces the closure strip at a construction joint

Closure Strip FAQ

What is a closure pour in concrete? +
A closure pour is the section of concrete left out at a construction joint and cast later, after the slabs on either side have shrunk. Leaving the strip open lets the adjacent concrete go through most of its drying shrinkage first, so restraint-to-shortening does not crack the finished slab. The reinforcement sits exposed in that open leave-out until the closure is poured. It is the same detail engineers also call a delay strip, pour strip, pour stop, or shrinkage strip. PS=Ø replaces that open leave-out with an ICC Approved, ACI 318 Type 1 and Type 2 compliant mechanical rebar splice that keeps the reinforcement continuous while the slab still shortens naturally.
What is the difference between a closure pour and a delay strip? +
There is no structural difference. Closure pour, delay strip, pour stop, and shrinkage strip all describe the same thing: a strip of slab left out at a construction joint and cast later so the adjacent concrete can shrink first. Which name a project uses comes down to region, trade, and habit. A structural engineer might spec a delay strip, a superintendent calls it the closure pour, and the concrete crew calls it the pour stop. PS=Ø targets that one detail regardless of what it is labeled on the drawings.
How long does a closure pour stay open? +
Traditionally a closure pour or delay strip is left open for weeks, commonly cited as 30 to 60 days, so the adjacent slabs can complete most of their drying shrinkage before the strip is cast. The exact window depends on the mix, curing conditions, span, and how much restraint-to-shortening the engineer of record needs to relieve, so the final number belongs to the design team. During that whole period the leave-out sits open on the critical path with exposed rebar, and other trades have to work around the gap. PS=Ø removes that wait by carrying the reinforcement across the seam with a mechanical splice, so the concrete still shortens but the joint does not sit open blocking the schedule.
Can you eliminate closure pours on post-tensioned slabs? +
Yes. Post-tensioned slabs shorten more than conventionally reinforced ones because the tendons actively compress the concrete, which is exactly why PT structures rely so heavily on closure strips and delay strips to release that shortening. PS=Ø is engineered for reinforced and post-tensioned work: the splice lets the slab shorten and cure naturally, then the couplers are grouted to complete a continuous, code-compliant connection. That eliminates the open closure pour without eliminating the movement the strip was there to allow.
Do you still need a closure pour if you use PS=Ø? +
No open leave-out. PS=Ø replaces the traditional open closure pour with a small grouted closure strip built around the couplers. The couplers and closure strip go in where the pour stop would sit, so the crew is not leaving an open gap with exposed rebar across the deck. The concrete on either side still shortens as it would with a delay strip, then the couplers are grouted to close a continuous, ICC Approved, ACI 318 Type 1 and Type 2 compliant connection.
Is a closure pour a type of construction joint? +
Yes. A closure pour lives at a construction joint, the stop-and-start line between two placements poured on different days. The construction joint is the interface; the closure pour is the strip of concrete left out at that interface and cast later. It sits alongside expansion, contraction (control), and isolation joints in the broader family of concrete movement joints, but it is the one specifically tied to sequencing placements and relieving shrinkage before the connection is made.
Expansion Joint Technical Detail

Expansion Joint Spacing, Comparison & FAQ

The deep-dive companion to our simplified Expansion Joints page: spacing considerations, how expansion joints compare to control and construction joints, why they crack and leak, the PS=Ø-EJ installation sequence, and the engineering FAQ.

How far apart should expansion joints be in a concrete slab?

Spacing is a structural decision, not a rule of thumb. It follows from slab thickness, mix design, the restraint conditions at columns and walls, and the temperature swing the structure will see. That is why the engineer of record sets it, and why two decks of the same size can call for very different layouts. The variables that drive the spacing decision:

  • Restraint-to-shortening. Stiff cores, shear walls, and columns fight the slab as it shrinks. The stiffer the restraint, the more the detailing has to relieve it.
  • Mix and curing. Higher-shrinkage mixes and short curing windows move more, sooner, which pushes joints closer together.
  • Thermal exposure. Exposed decks and podium slabs cycle harder than conditioned interior floors.
  • Post-tensioning. PT slabs shorten dramatically at stressing, so the movement to accommodate is larger and the detailing more demanding.

Expansion joints vs control joints vs construction joints

All three interrupt the slab, but they solve different problems. A control joint decides where a crack goes. A construction joint marks where one pour ended and the next began. An expansion joint leaves a real gap so sections move independently. The distinction that matters to a structural engineer is whether reinforcement has to be carried across the interruption, because that is the case PS=Ø-EJ addresses.

Joint type What it does Why it exists Carries rebar across?
Control joint Tooled or sawn weakness that steers cracking to a planned line Shrinkage cracking is inevitable, so it is directed instead of resisted Usually not full depth
Construction joint Interface where one placement stops and the next begins A pour was too large to finish in one placement Yes, typically doweled or lapped
Expansion joint Full-depth gap letting sections move independently Relieve restraint-to-shortening and thermal movement Left open and sealed, permanently
PS=Ø-EJ splice Mechanical rebar splice that lets the structure move, then connects to restore structural continuity Remove the permanent open joint while keeping the movement Yes, and eliminates the gap where appropriate

Why do concrete expansion joints crack and leak?

The concrete is rarely the culprit. The failure starts at the sealant, and once water gets into the gap the damage compounds. On a structural deck that water eventually reaches the reinforcement, which is where a cosmetic problem turns into a durability problem.

The sealant is a consumable

Joint sealant hardens, shrinks, and pulls away from the joint face over time. It was never meant to last the life of the slab, which is why it lands on the maintenance schedule.

Movement never stops

The joint opens and closes with every thermal cycle. Each cycle works the sealant loose a little more until the bond breaks and the gap is open to water.

Water reaches the rebar

Once water sits in the gap, freeze-thaw widens the crack and, on a structural deck, corrosion reaches the reinforcement. That is the failure a grouted splice removes by closing the seam where appropriate.

Eliminating the permanent open joint where appropriate also eliminates the associated sealant line, reducing the potential for leakage and ongoing joint maintenance for the life of the structure.

How PS=Ø-EJ eliminates the permanent expansion joint

  1. 1

    Engineered shop drawings

    Our engineers detail the splice into your structural design so it carries the reinforcement across the seam and holds the structural intent the permanent joint would have compromised.

  2. 2

    Couplers set in place of the joint

    The couplers and closure strip go in where a leave-out or delay strip would normally sit, so crews are not leaving an open gap and exposed rebar on the deck.

  3. 3

    The structure moves during construction

    Concrete shrinkage, post-tensioning, and temperature changes move the structure off the critical path, the way the joint was there to allow.

  4. 4

    Connect the reinforcement to restore continuity

    After the building is enclosed and the appropriate initial movement has occurred, the couplers are grouted to restore a continuous, ICC Approved, ACI 318 Type 1 and Type 2 compliant connection, eliminating the permanent joint where appropriate.

Expansion Joint FAQ

What is an expansion joint in concrete? +
An expansion joint is a deliberate gap left between two concrete pours so the slabs can move independently as concrete shrinks during curing and expands or contracts with temperature. The gap is filled with a compressible material or sealant so movement does not crack the surrounding slab. On reinforced and post-tensioned structures, PS=Ø-EJ replaces that gap with a mechanical rebar splice: the structure still moves during construction, then the reinforcement is connected once the appropriate initial movement has occurred, eliminating the permanent joint where appropriate.
How far apart should expansion joints be in a concrete slab? +
Spacing depends on slab thickness, mix design, restraint conditions, and temperature swing, so the number belongs to the structural engineer of record, not a rule of thumb. Traditional detailing places joints wherever restraint-to-shortening forces would otherwise crack the slab. The engineering angle we work from is different: instead of asking how often to interrupt the slab, we ask whether the joint needs to remain permanent once a self-supporting splice can carry the reinforcement across the seam.
What is the difference between expansion joints, control joints, and construction joints? +
A control joint is a tooled or sawn weakness that tells a slab where to crack. A construction joint is where one pour stops and the next begins, usually because a placement was too large to finish in one day. An expansion joint is a full-depth gap that lets adjoining sections move independently. All three interrupt the slab. PS=Ø-EJ targets the case where reinforcement has to be carried across that interruption, restoring the structural connection where appropriate once the initial movement has occurred.
Why do concrete expansion joints crack and leak? +
The failure is almost always at the sealant, not the concrete. Sealant is a consumable: it hardens, shrinks, pulls away from the joint face, and lets water into the gap. Freeze-thaw cycling then widens the crack, and on structural decks that water reaches the reinforcement. Eliminating the permanent open joint where appropriate also eliminates that sealant line, reducing the potential for leakage and ongoing maintenance.
Do expansion joints work in post-tensioned concrete? +
Post-tensioned slabs move a great deal as the tendons are stressed and the concrete shortens, which is exactly why restraint-to-shortening detailing is so demanding on PT structures. PS=Ø-EJ is engineered for reinforced and post-tensioned work: the structure moves during construction, then after the building is enclosed and the appropriate initial movement has occurred, the couplers are grouted to complete a continuous, code-compliant connection. It is an ICC Approved, ACI 318 Type 1 and Type 2 compliant mechanical rebar splice.
Do concrete expansion joints require ongoing maintenance? +
Yes, a conventional permanent expansion joint has a sealant line that has to be inspected, cleaned, and replaced on a cycle for the life of the structure, and cover boards or nosings on trafficked joints wear and get re-set. Eliminating the joint where appropriate removes that maintenance line item entirely. Our engineers can walk a project team through where a joint is genuinely required versus where a splice removes it.

FAQs

What Are Pour/Delay Strips?

A pour strip (or delay strip, closure strip, pour back) is a temporary gap—typically 3 to 6 feet wide—left in a concrete slab during construction to allow for shrinkage and minimize cracking.

Why Are Pour Strips Necessary?

Pour strips are used to mitigate the restraint-to-shortening that occurs as concrete cures. By leaving a pour strip, the surrounding slab can shrink without impact from restraint forces.

Why Are Pour Strips Left Open So Long?

Concrete shrinkage happens gradually – most shrinkage happens within the first year after the concrete is poured. Leaving the pour strip open longer allows the most shrinkage to occur and will deliver higher quality concrete.

Why Are Pour Strips So Problematic?

Because they increase costs, delay schedules, inhibit workflow, and create safety hazards.

What Are The Replacement Options For Pour Strips?

PS=Ø is the only system that is equivalent to a traditional pour strip. The PS=Ø system allows concrete to shrink naturally without cracking, while also eliminating the construction delays caused by traditional pour strips. Delivering a clean, continuous slab without obstructing the work of other trades.

How Do I Start Using PS=Ø On My Project?

Getting started is easy - Our team of experts are ready to help you implement our system into your project, providing guidance every step of the way. We'll ensure you understand all the benefits, including how it will streamline the entire construction workflow and shave months off your schedule. Contact us today!

How Does PS=Ø Accelerate My Construction Schedule?
Do I Have To Design The PS=Ø System?
My Project Is Already Started, Can I Still Use PS=Ø?
How Does PS=Ø Improve Concrete Quality?
How Does PS=Ø Reduce Costs?
How Can I Learn If PS=Ø Is Right For My Project?
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