A Banded Pallet and a Meter in the Van
The pallet lands on the slab still in its shrink wrap: European oak blocks, 280 by 70 by 20 millimetres, banded in layers, with a label on the crate declaring the moisture content they left the mill at. Somewhere in the van there is a resistance meter with pins that may or may not have been calibrated this year. Between those two objects sits the whole job. One tells you what you were sold; the other tells you what actually turned up, and on a wood block floor the difference between them is the difference between a floor that quietly closes up over its first heating season and one that has opened along every joint by February.
A parquet floor is bonded, not floated. Every block is bedded across its full underside and the bond is meant to hold for the life of the floor, so the field cannot travel as one sheet the way a click-jointed floor does. There is no slip plane and nothing to slide on. When the blocks give up moisture they pull against the adhesive, and that pull comes out somewhere: as hairlines distributed through a few hundred joints if the timber was right, as a delaminated patch or a lifted border if it was not. Everything below is arranged around keeping the movement small enough that the joints can swallow it.
Which is, in the end, what blocks are for. Cut a floor into 280-millimetre pieces and turn every second one through ninety degrees and you have halved the cross-grain timber lying in any one direction, because roughly half the material a line across the room now crosses is long grain, and long grain barely moves at all. The pattern is not only something somebody liked the look of. It is a movement device several centuries old, and it is the reason a solid oak floor five metres wide can exist without a break through the middle of it.
What a bonded block floor is made of
- Parquet blocks — counted by the repeating unit of the pattern rather than by the individual piece, with the border and margin taken off the field before anything is multiplied Parquet Wood Flooring Block Calculator
- Perimeter void — sized from the movement the field will actually make between the moisture it was fixed at and the moisture the room settles to, then left open and compressible Timber Cross-Grain Shrinkage Calculator
- Elastic adhesive bed — part of the movement system rather than a fixing: it has to hold the block down while still yielding to the small movement the block keeps making
- Surface damp-proof membrane — the barrier between a base still giving up water and a floor that is about to be sealed on top of it
- Levelling screed — brings the base inside the flatness the adhesive needs, since a hollow under a bonded block is an unsupported block Self-Leveling Underlayment (SLU) Volume Calculator
- Base slab — the structural deck, and on a new build the thing still releasing the moisture that decides when the floor is allowed to go down Concrete Calculator
The Number on the Pack and the Number in the Room
Solid parquet elements with grooves or tongues are described by EN 13226, and wood flooring is placed on the market under EN 14342, which is the standard governing what a manufacturer has to declare about it; EN 13756 supplies the vocabulary, which matters more than it sounds when a quotation and a crate label disagree about what a block is. Between them those documents fix that the elements leave the factory inside a stated moisture band and that the band is declared rather than assumed. Read the declaration on the pack. Do not reach for a figure remembered from another product, because the bands are not the same across the parquet standards and are certainly not the same across species.
Then meter the blocks yourself, because a declaration describes the day the product was made and says nothing about a container that crossed the North Sea in November or a pallet that stood a fortnight in an unheated store. ASTM D4442 is the reference method, oven-dry on a real specimen, and ASTM D4444 covers the calibration of the hand-held meters everybody actually uses. Split a block from the middle of a layer, push insulated pins into the fresh internal face rather than reading a surface that has been breathing site air, and apply the species and temperature corrections the meter maker publishes. One reading is an anecdote. Take six from different parts of the delivery and look at the spread as much as the average.
The base gets the same treatment, and a bonded floor is the least forgiving covering to lay over a doubtful one, because the adhesive line has to survive whatever comes up through it. ASTM F2170 reads relative humidity from in-situ probes at depth and under service conditions, which is the measurement that means something; a surface test describes the top few millimetres and the weather. In the British system BS 8201 is the code of practice for installing wood and wood-based flooring and sets out the same discipline of proving the base before committing to it. Where the base fails, the answer is a surface damp-proof membrane and a cure period written into the programme, not a heavier adhesive.
Last comes the number nobody measures, because it lies in the future: where the room will settle. The USDA Forest Products Laboratory's Wood Handbook, FPL-GTR-190, publishes recommended moisture contents for interior woodwork and puts most of the United States near eight per cent, lower through the dry Southwest and higher along the Gulf and Atlantic coasts. Eurocode 5 describes a heated, occupied interior as service class 1, an environment in which most softwoods will not exceed twelve per cent. ASHRAE Standard 55 caps how humid an occupied space may be and sets no lower limit at all, so the dry end of the band a wood floor needs is something a specification has to add rather than something the services already hold; in a house with no humidity control the honest answer is a range rather than a number. Whichever you take, write it down, because it is the second input to every calculation on this page.
- Photograph the crate label and its declared moisture content before the banding is cut, while it still belongs to an identifiable delivery.
- Split one block from the middle of a layer and meter the fresh internal face; repeat on six blocks drawn from different parts of the pallet.
- Apply the meter maker's species and temperature corrections, and record the meter's last calibration date on the same sheet.
- Take the base reading with in-situ probes to ASTM F2170, left for the equilibration period the method requires, and log ambient temperature and relative humidity beside it.
- Decide and record the in-service moisture content the room will run at, taken from the regional interior figure rather than from the conditions on the day.
- Keep all of it in the job file. Every argument about a bonded floor two winters later is an argument about what the moisture content was on the day, and the file is the whole of the defence.
Conditioning Is Not the Same as Waiting
A wrapped pallet standing in a warm hall is not conditioning; the wrap is a vapour barrier and the blocks inside it are still at whatever they arrived at. Break the bands, cross-stack the blocks with stickers so air can reach both faces, and run the building's heating at the setpoint the occupier will actually use. Then stop counting days and go back to the meter, because the target is a reading, not a duration. The National Wood Flooring Association's installation guidelines frame it the same way: what matters is the spread between the flooring, the subfloor and the service conditions of the finished building, not a number of nights on site.
This is also the point at which a programme gets told the truth. A shell with wet plaster drying, a screed still curing and doors standing open will condition blocks to a moisture content the finished building never sees, and take it straight back once the heating runs properly. Conditioning into a building that is itself still drying out is worse than not conditioning at all, because it produces a confident meter reading that is wrong in the one direction nobody checks for. Where the building cannot be brought to service conditions, dehumidification is the honest lever — and the pallet stays banded until it can be.
How Far the Field Actually Wants to Move
Below the fibre saturation point, timber changes dimension in proportion to the change in its moisture content, and the constant of proportionality is the dimensional change coefficient the Wood Handbook tabulates species by species in both directions. Flat-sawn oak sits near 0.0037 across the grain, a little over a third of one per cent of the width for each single point of moisture change, and the same species quarter-sawn moves at roughly half that. Along the grain the figure is a small fraction of either and is ignored in practice. Two things follow at once: how the blocks were cut matters as much as which tree they came from, and a pallet mixing flat-sawn and rift material will not move uniformly across a room.
Apply it to a field rather than to one block. In a herringbone or a basketweave, half the blocks on any line across the room present their width and half present their length, so the cross-grain timber you cross is about half the room dimension. Take a room five metres wide in flat-sawn oak, blocks metered at nine per cent and a room that will run at seven: two and a half metres of cross-grain timber, a coefficient of 0.0037, a two-point drop, and the field wants to shrink some eighteen and a half millimetres overall — call it nine millimetres arriving at each wall. That is an entirely ordinary perimeter void, and it is why the trade's habitual ten to fifteen millimetres works on floors whose timber was metered.
Run the same room with blocks that came in at fourteen per cent because they stood in a cold store, and the answer is around sixty-five millimetres. No void of any width you could hide behind a skirting absorbs that. The floor gaps along hundreds of joints, the border parts company with the field, or a bonded area simply lets go. That is the argument the arithmetic exists to win: on a block floor the moisture content at fixing is the control and the perimeter void is only the tolerance around it. Treat the figures as a ceiling rather than a forecast — the adhesive restrains part of it, compression set absorbs part of it, and no field is loaded evenly — but a ceiling that lands at sixty-five millimetres is telling you not to lay the floor this week.
| Metered at fixing | Across the whole field | Arriving at each wall | What it means on site |
|---|---|---|---|
| 8 % | 9.3 mm | 4.6 mm (0.18 in) | Inside anything a skirting hides; the joints take it and nothing shows |
| 9 % | 18.5 mm | 9.3 mm (0.36 in) | The ordinary case for metered stock, and the origin of the habitual 10–15 mm void |
| 10 % | 27.8 mm | 13.9 mm (0.55 in) | At the top of what a void and a skirting can honestly cover — check the border detail first |
| 12 % | 46.3 mm | 23.1 mm (0.91 in) | Beyond the perimeter. Condition the blocks or expect visible gapping through the field |
| 14 % | 64.8 mm | 32.4 mm (1.27 in) | A stop. Nothing about the perimeter detail is worth discussing until the timber has dried |
| 16 % | 83.3 mm | 41.6 mm (1.64 in) | Green stock for an interior floor; the blocks are not ready to be a floor yet |
Enter about half the room's width as the cross-grain depth, because a herringbone or basketweave field alternates grain direction block by block. The depth field caps at 1.5 m, so split a wide room into equal bands and use the level count for the number of bands: the accumulated figure is then the movement across the whole floor, and half of that is what arrives at each wall.
The summed depth of horizontally laid timber the load path passes through at one level.
The meter reading taken on the timber at the moment it was fixed in place.
Where the timber will settle once the building is finished and running.
The fraction of its depth the timber moves for each single point of moisture change.
How many platform-framed levels the movement accumulates through.
Cross-grain movement at one floor level
0.2749 in
Straight arithmetic on the coefficient and the moisture change entered. The movement is across the grain; along the grain the same change moves the timber by a small fraction of this and is normally ignored.
- Accumulated movement over all floor levels
- 0.82 in
- Depth remaining once the movement has happened
- 11.48 in
- Movement for a single point of moisture change
- 0.03 in
- Change in moisture content
- 9 %
- Proportion of the depth lost
- 2.34 %
They open the calculator with your figures already in it
Timber Cross-Grain Shrinkage Calculator: 0.2749 in — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Add the equipment this sizes
This result is a specification — 0.2749 in — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
What this calculation does not cover
- Movement across the grain only. Timber moves along the grain by a small fraction of this, and a long member's length is effectively stable.
- Says nothing about whether the movement will be RESTRAINED. A member free to shrink simply shrinks; the split the guide describes happens when two rigid fixing lines hold a deep section apart while it tries to move, and that is a detailing question this arithmetic cannot answer.
- Uses one coefficient for the whole stack. Where the plates, the rim and the joists are different species or different sawing patterns, run them separately and add the results.
- Ignores creep, mechano-sorptive movement under sustained load, and any moisture cycling. A detail that dries, wets and dries again does not simply return to where it started.
Cutting the Void, and Then Not Filling It
Size the void from the number rather than from the last job, then run it at every vertical the field can touch: walls, columns, the hearth kerb, pipe boxings, door linings and the front edge of a stair nosing. The traditional detail is a cork strip standing in the gap, compressible enough to leave the void a void and stiff enough that a sander does not drag it out. Where a wet area needs the edge closed, the filler has to stay compressible for the life of the floor, which rules out most of what is convenient.
What must not happen is the void being closed with anything rigid. A bead of hard adhesive, a run of grout where the parquet meets a tiled hearth, or a skirting scribed hard down onto the blocks all convert a free edge into a fixed one, and the movement then reports somewhere with less patience — usually out in the field, where it shows and where the repair means lifting bonded blocks. Skirting fixes to the wall and covers the void; scotia, where the skirting is already up, fixes to the skirting and never down through the blocks.
Photograph the perimeter with the cork in and the joinery off. That photograph is the only surviving evidence the void was ever cut, and on a disputed floor two winters later it is the first thing anybody asks to see.
Counting by the Repeat, Not the Piece
Take the field off first, inside the border, because the border and margin behave differently and are counted by the running metre. A room measuring five metres by four point two is twenty-one square metres gross; take a border of blocks laid crosswise off each side — 280 millimetres of it — with a single-block margin of 70 inside that, and the field is nearer fifteen. Those six square metres are not a rounding error. At normal block sizes they are several hundred pieces, often in a contrasting species, and increasingly often on a different lead time.
Then count by the repeating unit rather than by the block. A single 280 by 70 block is under twenty thousandths of a square metre, below the smallest unit the block calculator will take, and there is a good reason not to force it: on a patterned floor the piece is not what repeats. Two blocks make one herringbone step at about 0.039 square metres, four make a basketweave square, and a mosaic panel of fingers arrives as a single 480-millimetre unit at roughly 0.23 square metres. Enter the repeat, read the count of repeats, and multiply by the pieces inside it — a fifteen square metre field of two-block steps at fifteen per cent waste comes out at 443 repeats, which is 886 blocks, which is the figure that goes on the order.
One allowance, applied once. If the pattern waste has already been added to the area upstream, the piece count that follows is worked from the grossed-up figure with no further allowance; if it has not, add it here. Both routes are defensible and doing both quietly orders about a fifth more floor than the room needs.
Order the whole quantity from one production lot and leave a sealed box on site. Colour and grain vary between runs of solid timber far more than between runs of a manufactured plank, and the block wanted in year four is invariably the one lifted for a leaking radiator valve. Where field and border are different species, order both at once and condition them in the same room: two species delivered at two moisture contents will not settle together, and the joint between them is the first place that shows.
Run the field area from inside the border, entering the pattern's repeating unit as the block area — two blocks for a herringbone step, four for a basketweave square, or a mosaic panel as it comes — then multiply the answer by the pieces in that repeat.
SettingsSettings for this calculation
The standard allowance most suppliers and estimating guides assume for ordinary work.
The total floor area to be covered with parquet blocks.
The face area of a single parquet block — a 300 × 300 mm block is 0.09 m², a 12 × 12 in block is 1 sq ft.
Extra blocks for cuts around edges, corners, and breakage.
Parquet blocks needed
250 blocks
They open the calculator with your figures already in it
Parquet Wood Flooring Block Calculator: 250 blocks — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Estimated cost — your price
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.
What this calculation does not cover
- Solid wood blocks arrive at a moisture content and then move. They should be acclimated in the room at the humidity that room will actually run before any adhesive is spread, and the field has to be laid to a perimeter expansion gap - commonly 10 to 15 mm, hidden under the skirting - because blocks butted hard to the walls have nowhere to go in a wet August and lift at the joints. Nothing on this page reduces the area for that gap or asks about the screed, and a slab still giving off moisture will push a parquet floor off it whatever the block count was.
- Blocks are the cheap half of a parquet floor. The adhesive is a separate quantity set by the trowel notch and the block's backing, usually quoted as a spread rate per unit of area, and a newly laid solid floor is then sanded through several grits and sealed with three or more coats of lacquer or oil, each with its own coverage rate. On a small room those consumables and the machine hire can easily outweigh the blocks, and none of them scale with the block count.
- Says nothing about the height the floor builds to. Adhesive bed plus block thickness lifts the finished surface 20 mm or more above the screed, which decides whether doors still swing, whether the threshold into the next room can be made at all, and how the floor meets an existing skirting - and sanding a solid block floor takes roughly another millimeter off the top. That build-up is checked at the doors before the blocks are ordered, not after they are down.
The Bed, and What Is Under the Old One
Historically these floors were laid in hot bitumen, which is why lifting a mid-century block floor so often exposes a black, brittle bed. Take that seriously before a scraper goes near it. Bituminous and cutback flooring adhesives of that era can contain asbestos, and disturbing them is work governed by OSHA 29 CFR 1926.1101 in the United States, with the demolition and renovation notification requirements of the EPA asbestos NESHAP at 40 CFR Part 61 Subpart M alongside it, and by the equivalent control-of-asbestos regime elsewhere. Sample before stripping. A refurbishment that assumed a morning with a scraper and turned into a licensed removal has stopped being a flooring job.
Modern practice is a full-bed elastic adhesive, silane-modified polymer or two-part polyurethane, selected against EN 14293, the standard covering adhesives for bonding parquet to a subfloor and the minimum requirements they have to meet. Elastic is the operative word and it belongs in this guide rather than in a bonding checklist: the bed is part of the movement system. It has to hold each block down while yielding to the small movement the block continues to make, which is exactly what a rigid, high-modulus adhesive will not do — it transfers the movement into the joint instead, and the joint is thinner than the bed.
Water-based dispersion adhesives belong on some engineered products and not on solid blocks, for the plain reason that the water goes straight into timber you have just spent a fortnight conditioning. The same logic rules out wetting the base for any reason once the blocks are conditioned, and it is why the surface damp-proof membrane, where the base test called for one, goes on and cures before the pallet is broken rather than after.
Heat From Below Moves the Target
A heated screed does not change the arithmetic; it changes the number you put into it. Timber over a running system settles drier than the same timber in the same room unheated, so the in-service figure is the heated-season one, not the reading taken on commissioning day with the system cold. Getting that wrong is the quiet version of the mistake in the table above: the calculation reports a comfortable movement, the floor is laid, and the first full heating season finds another two points of drying nobody allowed for.
The specification answer is the sawing pattern. Quarter-sawn and rift material moves at roughly half the tangential rate, which halves everything in the table for the same room and the same moisture swing, and that is why heated floors are so often specified quarter-sawn rather than simply thinner. Commission the screed through its full heat-up and cool-down cycle before any block goes down, hold the surface temperature to the flooring manufacturer's stated ceiling, and take the in-service meter reading with the system running as it will actually run.
Reading the Floor in February
Hand over a range, not a reassurance. Give the occupier the relative humidity band the floor was laid to and say plainly what sits outside it, because a house heated hard through a dry winter runs well below anything a solid wood floor was designed for, and the remedy is humidification rather than complaint. This is where ASHRAE Standard 55 stops being an abstraction and stops being sufficient in the same breath, because its humidity provision is an upper limit and the winter problem is at the other end: a building that holds the range the floor was laid to holds the floor's moisture content, and one that does not, does not.
Teach the three failure pictures, because they have opposite causes and get confused constantly. Fine gaps distributed evenly across the whole field, opening in winter and closing in summer, are a floor drying and rewetting inside its range and generally need nothing done. Cupping — blocks higher at the edges than the centre — means the underside is wetter than the top, which points at the base, a leak, or a membrane that was left out. A tented or hollow-sounding area means the field ran out of room: the void was closed, something rigid was butted against the edge, or the blocks went down wetter than the room they were laid in.
When it is disputed, go back to the meter rather than to opinion. Lift one border block, meter the fresh face, and set that reading against the six taken at delivery and against the in-service figure recorded before laying. Those three numbers on one sheet settle almost every argument a bonded block floor generates, and they take about ten minutes — which is the whole reason for writing the first two down at the time.
Before the banding comes off the pallet
The order the numbers have to exist in on a block floor: prove the base, prove the timber, then count what goes on top of it.
- Base relative humidity, dated — In-situ probes to ASTM F2170, left for the method's equilibration period and read under service conditions — not a surface test on installation morning.
- Block moisture content at delivery — Six readings on split blocks from different parts of the pallet, species and temperature corrections applied, recorded beside the declared figure on the crate.
- In-service moisture content for the room — The figure the finished, heated building will hold, taken with any underfloor system running as it will run. It is the second input to every movement number on the job.
- Field area inside the border — Gross room area less border and margin. The border is a separate quantity by the running metre, often a different species and a different lead time.
- Pattern repeat, and the allowance applied once — Two blocks to a herringbone step, four to a basketweave square, a mosaic panel as one unit — then multiply repeats by the pieces inside them.
- Perimeter void and cork — Sized from the calculated movement arriving at each wall, run at every vertical the field can touch, and left compressible under the skirting.
Opens the calculators above on one screen with the dimensions from this article already filled in. Quantities only — this site publishes no price list, because local prices vary too much to publish honestly.