Why does a permeable pavement need topping up during construction?

Because compaction is what settles the stone into the joint, and the joint that looked full before the plate compactor went over it is no longer full afterwards. The standard sequence is fill, compact, refill and compact again until the joints stop taking material, and the allowance in this calculation is what covers that second and third pass.

Can I use jointing sand instead of stone?

Not in a permeable pavement. Sand is graded to fill its own voids and will seal the joint, which removes the only path water has into the structure — the pavement then behaves as an impermeable surface with an expensive reservoir underneath it. Jointing material here is a small, clean, single-sized crushed aggregate chosen for the voids it keeps open.

How often will the joints actually need replenishing?

When a measured drop in infiltration rate says so, rather than on a date in a diary, and how soon that comes depends almost entirely on what reaches the surface. A car park catching silt off adjacent landscaping clogs far faster than a courtyard with no run-on. The quantity per round is what this gives you; the interval comes from testing the pavement.

Is this the same calculation as mortar in an ashlar stone joint?

No, and the two answer opposite questions. A masonry joint calculation works out the volume of mortar that fills the gap between cut stones in a wall and seals it. This works out the mass of loose, single-sized stone poured into the openings of a horizontal pavement specifically so the joint stays open, and it repeats for every maintenance round the pavement's life includes.

Materials & Quantities

Permeable Pavement Joint Fill Stone Calculator

Jointing stone for a permeable pavement: the first fill, the top-up the joints take during compaction, and what each later replenishment round needs.

Answers as you typeNo submit button
Every formula citedNamed published standards
Calculated in your browserNo account, nothing uploaded

SettingsSettings for this calculationUS

Market

Imperial · sales tax

Laid Pavement Area

The plan area of permeable surfacing being laid.

Use the area of permeable units only. Solid edge courses, kerb lines and any conventional paving inside the same layout carry no jointing stone and should be left out, since including them inflates a quantity that is already easy to over-order.

Open Area of the Units

The proportion of the surface made up of joints and apertures.

Take this from the paver manufacturer's data, because it varies widely between a narrow-jointed interlocking unit and a large-aperture grid, and it varies again with the laying pattern. It is the single input that most moves the answer.

Depth of Joint Fill

How deep the stone sits in the joint or aperture.

Usually the full depth of the unit, since the joint stone runs down to meet the bedding course. Where the aperture is tapered or partly closed at the base, the effective depth is less than the unit is thick and the quantity falls with it.

Loose Bulk Density of the Stone

The delivered bulk density of the jointing aggregate.

Small single-sized angular stone is bulky and light for its volume, and the figure moves with the gradation, the parent rock and how wet the load is. Get it from the supplier for the material actually being delivered rather than accepting a generic value.

Compaction Top-Up Allowance

Extra stone the joints take as the pavement is vibrated and refilled.

Joints are filled, compacted, and filled again — often more than once — because vibration settles the stone and opens the joint back up. A rule of thumb rather than a published figure, and worth revising upward on units with wide apertures.

Replenishment per Maintenance Round

Proportion of the joint volume replaced at each cleaning cycle.

Vacuum sweeping to restore infiltration removes the clogged upper part of the joint along with the silt, and that stone has to be put back. How much depends on the sediment load reaching the surface and on how aggressive the cleaning regime is.

Jointing stone for the first fill

1,940 lb

Medium confidence

Joint fill is the working part of a permeable pavement — it is where the water goes in, and a pavement whose joints have not been kept topped up stops infiltrating long before anything else in the build-up fails. Order the first fill with the pavers, and put the replenishment quantity into the maintenance plan rather than discovering it later.

Loose stone volume in the joints: 0.67 yd³
Stone before the compaction allowance: 1,685.55 lb
Stone for each replenishment round: 84.28 lb
First fill plus one replenishment round: 2,022.67 lb

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

ASCE/T&DI 68-18, Permeable Interlocking Concrete Pavement, which covers the construction and the maintenance regime that makes joint replenishment a recurring quantity rather than a one-off
ASTM D448 defines the standard size numbers used for jointing and bedding aggregate in permeable pavements; the gradation chosen changes both the void structure and the bulk density entered here
The top-up and replenishment percentages are rules of thumb, not published figures — the joints take more stone during compaction than their nominal volume, and lose some at every cleaning cycle, by amounts that depend on the unit, the plant and the site

Inputs used

Laid Pavement Area: 1080 sq ft
Open Area of the Units: 10
Depth of Joint Fill: 2 in
Loose Bulk Density of the Stone: 93.64 pcf
Compaction Top-Up Allowance: 15
Replenishment per Maintenance Round: 5

Intermediate steps

Loose stone volume in the joints: 0.67 yd³
Stone before the compaction allowance: 1,685.55 lb
Stone for each replenishment round: 84.28 lb
First fill plus one replenishment round: 2,022.67 lb

Safety / waste buffer appliedCompaction top-up allowance (+15%)

Final result1,938.39 lb

Confidence note: Joint fill is the working part of a permeable pavement — it is where the water goes in, and a pavement whose joints have not been kept topped up stops infiltrating long before anything else in the build-up fails. Order the first fill with the pavers, and put the replenishment quantity into the maintenance plan rather than discovering it later.

What this calculation does not cover

Jointing and aperture stone only. The bedding course, the open-graded base and subbase, geotextiles and edge restraints are separate quantities on their own gradations.
Does not size the pavement hydraulically. Whether the joints and the reservoir beneath them accept the design storm is an infiltration and storage calculation.

Estimated cost — your price

Price per lb ($)

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-08-30 · in the site-wide review of 2026-09-06 · v1.0.0

Regulatory standards & verification citations3

ASCE/T&DI 68-18, Permeable Interlocking Concrete Pavement, which covers the construction and the maintenance regime that makes joint replenishment a recurring quantity rather than a one-off
ASTM D448 defines the standard size numbers used for jointing and bedding aggregate in permeable pavements; the gradation chosen changes both the void structure and the bulk density entered here
The top-up and replenishment percentages are rules of thumb, not published figures — the joints take more stone during compaction than their nominal volume, and lose some at every cleaning cycle, by amounts that depend on the unit, the plant and the site

Which documents these citations point at

Standards referenced: ASTM D448 (ASTM International, United States).

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Draining a New Driveway So It Stays Permitted Developmentuses this calculator
A front drive whose water reaches the road is not permitted development: the porous surface, the receiving border, the application, and proving which you built.
Open-Graded Bedding: The Layer That Has to Stay Openuses this calculator
Fifty millimetres of single-sized stone that must never be compacted, walked on, or topped up with anything a quarry has not washed.
Getting a Dropped Kerb Built and Paved to Meet It

Called something else where you work? Sustainable drainage — the term in each market, how close the equivalence really is, and the standard that governs it.

Still deciding? Polymeric Sand vs Permeable Joint Fill — the factors that actually differ, with no invented prices.

How to calculate permeable pavement joint fill stone in 7 steps

Laid Pavement AreaThe plan area of permeable surfacing being laid.
Open Area of the UnitsThe proportion of the surface made up of joints and apertures.
Depth of Joint FillHow deep the stone sits in the joint or aperture.
Loose Bulk Density of the StoneThe delivered bulk density of the jointing aggregate.
Compaction Top-Up AllowanceExtra stone the joints take as the pavement is vibrated and refilled.
Replenishment per Maintenance RoundProportion of the joint volume replaced at each cleaning cycle.
Jointing stone for the first fillThe tool computes the jointing stone for the first fill from those figures and shows the formula, its sources, and a confidence rating alongside it.

Jointing stone for the first fill by laid pavement area

Page defaults, not your figures above.

Laid Pavement Area	Jointing stone for the first fill (lb)
500 sq ft	883
1,000 sq ft	1,767
1,500 sq ft	2,650
2,000 sq ft	3,533

Frequently asked questions

Why does a permeable pavement need topping up during construction?: Because compaction is what settles the stone into the joint, and the joint that looked full before the plate compactor went over it is no longer full afterwards. The standard sequence is fill, compact, refill and compact again until the joints stop taking material, and the allowance in this calculation is what covers that second and third pass.
Can I use jointing sand instead of stone?: Not in a permeable pavement. Sand is graded to fill its own voids and will seal the joint, which removes the only path water has into the structure — the pavement then behaves as an impermeable surface with an expensive reservoir underneath it. Jointing material here is a small, clean, single-sized crushed aggregate chosen for the voids it keeps open.
How often will the joints actually need replenishing?: When a measured drop in infiltration rate says so, rather than on a date in a diary, and how soon that comes depends almost entirely on what reaches the surface. A car park catching silt off adjacent landscaping clogs far faster than a courtyard with no run-on. The quantity per round is what this gives you; the interval comes from testing the pavement.
Is this the same calculation as mortar in an ashlar stone joint?: No, and the two answer opposite questions. A masonry joint calculation works out the volume of mortar that fills the gap between cut stones in a wall and seals it. This works out the mass of loose, single-sized stone poured into the openings of a horizontal pavement specifically so the joint stays open, and it repeats for every maintenance round the pavement's life includes.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.