Ontario's Plain-English Guide to Custom Home Buildingπ 705-533-1633 | βοΈ 1-866-868-6606 | βοΈ info@icfhome.ca
Manufactured Stone vs Natural Stone: What Each Is, How Each Goes on the Wall, Weight, Cost and How Each One Looks in Thirty Years
Exterior Finishes
Manufactured Stone Is Concrete Pretending, Natural Stone Is Rock Being Itself, and Both Can Be Done Badly: What Each Is, Costs and Becomes
From the sidewalk, good manufactured stone and real stone look the same, and for the first ten years they mostly are. After that they go their own ways. Manufactured stone is lightweight concrete cast in moulds taken from real rock and coloured on the surface; it costs about $32 a square foot installed and it ages like concrete. Natural stone is quarried rock, either sawn into inch-thick veneer at about $50 or laid full thickness by a mason at $65, and it ages like the Niagara Escarpment, which is to say not noticeably. Here is what each one is, how each goes on, what each weighs, and how to pick.
Side by side
| Manufactured stone | Natural thin veneer | Full-bed natural stone | |
|---|---|---|---|
| What it is | Lightweight concrete cast in rubber moulds, pigment on the face and sometimes through the mix | Real stone sawn to about 1 to 1.25 in. thick, corners cut in an L | Real stone, 3 to 5 in. thick, split or sawn, laid by a mason |
| Installed, mid grade | $32 | $50 | $65 |
| Installed, builder / premium | $26 / $38 | $42 / $62 | $55 / $85 |
| How it is attached | Adhered: barrier, lath, scratch coat, mortar on the back of every piece | Adhered, same system, with a heavier lath and a stiffer wall | Sits on a ledge, tied to the wall, 1 in. air space, weeps and flashing like brick |
| Weight on the wall | 8 to 12 lb per sq ft | 10 to 15 lb per sq ft | 35 to 50 lb per sq ft |
| Needs a ledge | No | No, but a weep screed and a sound sheathing | Yes: a poured ledge or a shelf angle, $45 a linear foot on an existing house |
| Absorbs water | Yes, like a concrete block; must have its barrier and drainage behind it | Depends on the stone; limestone some, granite almost none | Same, but the air space does the drying |
| A chip or a snowblower hit | Shows grey concrete under the colour | Shows the same stone | Shows the same stone, and the wall does not care |
| Colour in 30 years | Faded on the south and west walls, patchy where it has been wet | Unchanged, a little lichen on the north | Unchanged |
| Repair | Matching a discontinued profile and colour is the problem; patches show | Any similar stone blends in | A mason repoints it; the stone is not the problem |
| Resale | Reads as “stone” for ten years, as “builder stone” after | Reads as stone | Reads as money |
What manufactured stone is
Take a real rock, make a rubber mould of it, pour a mix of cement, lightweight aggregate and pigment into the mould, and you get a piece of stone-shaped concrete about 1.5 in. thick that weighs a third of what the rock did. The surface is coloured with oxides, either sprayed into the mould so the colour is a skin, or mixed through so a chip is nearly the same shade. Through-colour is the mid and premium product; a sprayed skin is the builder one. The difference is what you see after the first chip.
It is a good product with a bad reputation, and the reputation is earned by installers, not the stone. Set over two layers of barrier, on lath, over a scratch coat, with mortar buttered on the back of every piece and a weep screed at the bottom, it stays on the wall for decades. Set over one layer of house wrap, straight onto foam, with a dab of mortar in the middle of each piece, it falls off in sheets. The cheap stone quote is almost always the cheap installation, and stone veneer problems is the catalogue of what that produces.
What natural stone is, in its two forms
Thin veneer is real stone cut on a saw to an inch or so thick, flats and L-shaped corners, sold by the square foot and the linear foot like the manufactured product and installed the same way. Ontario limestone, Wiarton and Owen Sound stone, Eramosa, and imports from Quebec and the States. It costs more than manufactured because quarrying and sawing cost more than casting, and it weighs a little more, but the wall and the lath do not notice the difference. The face is stone all the way through, so it chips stone, weathers stone, and will not look like anything else in fifty years.
Full-bed stone is a masonry wall, not a cladding. The stone is 3 to 5 in. thick, it sits on a ledge formed in the foundation or a steel shelf angle, it is tied back to the structure, and there is an air space behind it with flashing and weeps at the bottom, exactly like brick. It is laid by a mason, one stone at a time, choosing each piece for the hole in front of him. It is the most expensive wall on this site and the only one that will outlive the house. A 600 sq ft front in full-bed stone is twelve to fifteen tons on the ledge, and support and ledges covers what carries it.
How each one ages, honestly
Manufactured stone fades. The pigments that give it colour are on or near the surface, and twenty years of Ontario sun on a south wall takes the warm tones out first, so a tan ledgestone drifts toward grey and a grey one drifts toward nothing. It also wicks water, and a wall that is wet from the splash line up shows it as a darker band with white efflorescence at the edges. None of that is structural. It is just a house that looks its age.
Natural stone does not fade, because the colour is the mineral. It gets lichen on the north side and a darker tone where it stays damp, which on stone reads as character and on concrete reads as neglect. Repairs blend because any stone from the same quarry matches. The thing that goes wrong with natural stone is the mortar, and a mason repoints it.
I have put all three on houses and I would put all three on again, in the right places. The ICF finishes article has stone against stucco and siding on an ICF wall with costs, so I will not re-run that here.
How I would decide
- A stone skirt, a chimney chase, a column wrap, a feature wall under a porch roof: manufactured stone, mid grade, through-coloured, installed by the book. $32 and nobody will know.
- A full front elevation that faces south or west: natural thin veneer at $50. The fade on 600 sq ft of manufactured stone facing the afternoon sun is what you will see from the driveway every day for the second half of the mortgage.
- A house you intend to die in, or an addition on a 1900 stone farmhouse: full-bed, $65 and up, and hire the mason before you hire the designer.
- Any stone on a wall with no second plane of protection: none of them, until the wall has one. The wall protection hub explains the barrier, the drainage and the flashing that every one of these needs behind it.
- Budget stone at $26: fine on a chimney chase. On a whole front, spend the extra $6 for the through-colour product and the installer who asks what lath you want.
Questions people ask
Is manufactured stone as good as real stone?
For the first decade, at a third of the weight and two thirds of the price, nearly. After that it fades, chips grey and is hard to match. Real stone does none of those things. Which matters depends on how long you plan to own the wall.
How can you tell manufactured stone from natural stone?
Look at a corner or a chip: manufactured shows grey concrete inside. Look at the pattern: cast stone repeats the same pieces every few feet because they came from the same moulds. Tap it: concrete sounds dull, stone rings.
Does manufactured stone need a ledge?
No. It is adhered to the wall with mortar over lath and a scratch coat and weighs 8 to 12 lb a square foot, which the wall carries. Full-bed natural stone needs a ledge or a shelf angle; thin natural veneer does not.
How much more is natural stone than manufactured?
About $18 a square foot more for thin veneer, $50 against $32 at mid grade, and $33 more for full-bed at $65. On a 600 sq ft front that is $10,800 and $19,800 respectively, before HST.
Can manufactured stone go over foam or over an ICF wall?
Over ICF, yes, with the barrier, lath fastened into the webs and a scratch coat; the foam is not the substrate, the lath is. Straight onto foam with mortar and no lath, no. It falls off.
Price both and decide
The exterior cladding cost calculator prices the same walls in manufactured, thin natural and full-bed stone side by side, with the ledge where full-bed needs it. If a quote says “stone” and not which one, the $99 review finds out, and if it priced a skirt in stone and the walls in something else, it checks the flashing between them.
Sources and further reading
- Canada Masonry Design Centre: masonry veneer support, shelf angles, weep holes, through-wall flashing and air space, in Canadian terms.
- Canada Mortgage and Housing Corporation: the Canadian wall-assembly and moisture research behind rainscreens and the second plane of protection.
- Ontario’s Building Code, Section 9.27 Cladding: the first and second planes of protection, sheathing membrane, flashing at openings and transitions, and the clearances from grade and roofs that every siding and stucco job has to meet.
