Dimensions / Building materials / Concrete blocks / Split-face block
A split-face block is cast as two units face to face and split apart after curing, so one face is rough and shows the aggregate (CMHA). Its height and length stay 7-5/8 × 15-5/8 in like a plain unit and are held to ±1/8 in, but the split face is exempt from C90’s tolerance. The width depends on the maker: the plain 3-5/8 to 11-5/8 in at Basalite and Westbrook, 1/4 in more on Mutual Materials’ 4, 6, 10 and 12 in units, and fluted units project further, 2-3/16 in past the face at County. Up to 10% of a split face shell may be thinner than C90’s minimum, but never under 3/4 in (NCMA). Units come with 1 to 11 vertical scores or 4, 6 or 8 ribs; an 8 in split unit weighs 43 lb in one Anchorage producer’s list.
| Face (height × length) | Tolerance, split face exempt | Split face shell, thinnest |
|---|---|---|
| 7-5/8 × 15-5/8in | ±1/8in | 3/4in19 mm |
Sources: Nitterhouse Masonry, CMHA, NCMA. Checked October 2026.
An 8 in split-face block, a 300 sq ft wall with its order, one block you measured and the thinnest point of its split face shell are filled in; change any of them.
Counts, modules and tolerances follow CMHA notes and the makers’ printed rules; nominal sizes include one mortar joint. No bar sizes or structural design here.
Each 8 × 16 in block face takes 8/9 sq ft with its joint, so a wall takes 1.125 blocks a sq ft (County Materials, CMHA). 300 sq ft with 5% for waste needs 355; you ordered 360, 5 spare.
Split units count the same as plain ones: 112.5 per 100 sq ft before waste.
ASTM C90 holds height and length to 1/8 in either way of the specified 7-5/8 × 15-5/8 in; the split face is exempt, so the width is not checked (CMHA). You measured 7.6 × 15.65 in: both within. The 7.8 in width is not held to the tolerance.
Mutual Materials makes 4, 6, 10 and 12 in split units 1/4 in wider than plain.
ASTM C90 asks face shells of at least 1-1/4 in for 8 in units, but up to 10% of a split face shell may be thinner as long as it is not under 3/4 in (NCMA); your thinnest point is 1 in.
C90 face shells: 3/4 in at 4 in, 1 in at 6 in, 1-1/4 in from 8 in up.
Selling split-face blocks? Photograph the split face and the end of a block, mark height, length, width at the split face and the face shell in SizeMarker, and send the picture with your quote.
Mark a photo| Unit | Size | Weight | Per pallet |
|---|---|---|---|
| Anchorage 4 in split face | 4 × 8 × 16 in nominal | 33 lb | 150 |
| Anchorage 8 in split faceThis page | 8 × 8 × 16 in nominal | 43 lb | 75 |
| Anchorage 8 in split half high | 8 × 4 × 16 in nominal | 19 lb | 150 |
| Anchorage 8 in split half | 8 × 8 × 8 in nominal | 25 lb | 150 |
| Anchorage 12 in split face | 12 × 8 × 16 in nominal | 55 lb | 50 |
| Basalite 8x8x16Smooth or split face, one row | 7-5/8 × 7-5/8 × 15-5/8 in | 40 lb | 90 |
| Mutual 4-8-16 split face | 3-7/8 × 7-5/8 × 15-5/8 in | — | — |
| Mutual 8-8-16 split face | 7-5/8 × 7-5/8 × 15-5/8 in | — | — |
| Thomas Armstrong RockfacedUK, a solid facing block | 440 × 100 × 215 mm | — | 56 (5.6 m²) |
| Beijing split blockChina, MU10 load-bearing | 390 × 190 × 190 mm; half 190 × 190 × 190 mm | — | — |
Sources: Alaska DOT&PF · Basalite · Mutual Materials · Thomas Armstrong · Beijing Housing and Construction Commission
| Item | Figure |
|---|---|
| Overall toleranceCMHA | ±1/8 in (3.2 mm) on width, height and length; split faces and slump faces are exempt |
| Non-split facesWestbrook; Nitterhouse | Height and length finished to 7-5/8 × 15-5/8 in |
| Ribs and scoresCMHA | Within ±1/16 in (1.6 mm) of their size and placement |
| Width, as plainBasalite; Westbrook | 3-5/8 to 11-5/8 in, the same as smooth units |
| Width, widerMutual Materials; Angelus | 1/4 in more: 3-7/8, 5-7/8, 9-7/8, 11-7/8 in (Mutual); Angelus’s 4 in solid split unit 3-13/16 in |
| Ribs past the faceWestbrook; County Materials | Westbrook 4-rib deep unit 9-1/4 in; County flutes extend 2-3/16 in from the face, sold as 8 + 2 |
| Face shellNCMA TEK 2-3A | Up to 10% of a split face shell may be under the minimum, but not under 3/4 in (19 mm) |
| C90 face shell minimumsCMHA; NCMA | 3/4 in at 3 and 4 in, 1 in at 6 in, 1-1/4 in at 8 in and up |
| UKThomas Armstrong | The rockfaced block is still declared tolerance category D1 |
Sources: CMHA · Westbrook · Nitterhouse Masonry · Basalite · Mutual Materials · Angelus Block · Westbrook · County Materials · NCMA · Thomas Armstrong
| Item | Figure |
|---|---|
| One scoreCMHA | The most common: looks like 8 × 8 in units in stack bond |
| More scoresCMHA; Superlite | 2, 3, 5 or 7 (CMHA); one to eleven on one or both sides (Superlite) |
| RibsCMHA; Westbrook | 4, 6 or 8 vertical ribs |
| Lining upCMHA | Units with two and five scores go in stack bond or one-third running bond so the scores align |
| Score sizeCounty Materials | 3/8 in square or 7/8 in deep V; depth and width vary by plant |
| MortarNCMA TEK 2-3A | Hard to tool properly between ribs |
Sources: CMHA · Superlite · Westbrook · County Materials · NCMA
| Item | Figure |
|---|---|
| Cast double, then splitCMHA; Echelon; Air Vol | Two units moulded face to face, cured, then split apart by a guillotine with four blades |
| Exempt faceCMHA; Angelus | The split face is not held to C90’s dimensional tolerance; only the non-split faces are |
| Thinner shell allowedNCMA | Up to 10% of the split face shell may be thinner than the minimum, down to 3/4 in |
| Smaller channelAngelus drawings | A split-face bond beam channel is 3-1/2 × 1-1/2 in, against 4 × 2-1/2 in in a precision unit |
| Wider than plainMutual Materials | Its 4, 6, 10 and 12 in split units are 1/4 in wider than the plain ones |
| ColourCMHA TEK 05-16 | Split faces show less colour variation than smooth faces |
| StockAir Vol; Basalite | Most split units are single open-end (Air Vol); 6 in split units are special order (Basalite) |
Sources: CMHA · Echelon · Air Vol Block · Angelus Block · NCMA · Angelus Block · Mutual Materials · CMHA · Basalite
7-5/8 in high and 15-5/8 in long like a plain unit; the width is 3-5/8 to 11-5/8 in at Basalite and Westbrook, and 1/4 in more on Mutual Materials’ 4, 6, 10 and 12 in units.
Its height and length do, to ±1/8 in; the split face itself is exempt, because splitting leaves a random surface (CMHA). Ribs and scores are held to ±1/16 in.
Up to 10% of it may be thinner than C90’s minimum, which is 1-1/4 in on an 8 in unit, but never under 3/4 in (NCMA).
43 lb for an 8 in unit, 55 lb for 12 in and 33 lb at 4 in in one Anchorage producer’s list; Basalite prints 40 lb for its 8 in smooth or split unit.
One vertical score is most common; CMHA lists 2, 3, 5 or 7, Superlite makes up to eleven, and ribbed units have 4, 6 or 8 ribs.
Two units are moulded face to face, cured and split apart, so the face is fractured and shows the aggregate (CMHA, Air Vol).
A buyer of split-face blocks asks for the height and length, the width at the split face, the number of scores or ribs, whether one or two faces are split, the colour and its batch, the unit weight and the pallet count. Mark those on a photo of your own block with SizeMarker, like the picture at the top, and share one card in WhatsApp or WeChat.
