Forest of Dean Pennant alternative: Northcliff Blue
Forest of Dean Pennant is one of the most recognisable sandstones of the British south west: it has paved Bristol and Cardiff for a century and a half, and it remains available today. This page does not set out to replace it, but to offer one more reference to anyone weighing blue-grey sandstones for paving or cladding: Northcliff Blue belongs to the same petrographic family, with notably lower water absorption and with the anchor load tested and published in its declaration of performance. The comparison presents the data for both stones, including the properties where the result favours Pennant.
Forest of Dean Pennant
- Type:
- Feldspathic, micaceous lithic arenite (Upper Carboniferous)
- Origin:
- Forest of Dean, Gloucestershire (UK)
- Colour:
- Blue to green-grey, with brown and iron-stained reddish variants
Pennant is still quarried today in the Forest of Dean: a vernacular, single-origin stone closely tied to the heritage of the British south west. This page does not answer a supply problem, but the search for a blue-grey sandstone with a documented technical profile.
Northcliff Blue
Blue-grey lithic arenite from our own quarry: the same petrographic family as Pennant, with 0.80 % water absorption and a declaration of performance signed in January 2026.
View stoneTechnical comparison
| Property | Forest of Dean Pennant | Northcliff Blue |
|---|---|---|
| Petrographic family | Feldspathic, micaceous lithic arenite | Lithic arenite |
| Colour | Blue to green-grey, with brown variants | Blue-grey |
| Water absorption | 2.50 to 2.60 % | 0.80 % |
| Flexural strength | 15.5 MPa (characteristic value) | 23.3 MPa |
| Flexural strength after 56 freeze-thaw cycles | 12.9 MPa (drops by 17 %) | 24.9 MPa (rises) |
| Same test and same standard on both stones, with opposite results. It is the most revealing durability figure in the table. | ||
| Compressive strength | 91 MPa (characteristic value) | 147 MPa |
| These figures do not share a statistical basis: a characteristic value is the lower threshold of the test and always sits below the mean. Compared mean to mean, the real margin is narrower than the bare numbers suggest. | ||
| Abrasion | 20 mm on the blue grade, 18.5 mm on the mixed grade | 18.5 mm |
| Equivalent values: on abrasion both stones play in the same league. | ||
| Wet slip resistance, textured finishes | 89 to 94 SRV depending on grade | Ask us, by finish |
| The published figure favours Pennant here. Our declaration of performance does not break slip resistance down by finish, so we prefer to send you the laboratory-confirmed flamed test rather than publish a figure without that breakdown. | ||
| Anchor breaking load | Not published | 2,050 N |
| Supply | Vernacular single-origin stone (Gloucestershire), closely tied to its region’s heritage | Our own quarry in Spain with in-house processing; lead time and availability confirmed by our team for each project |
Pennant is vernacular stone: in Pontypridd the conservation plan names it the predominant material of the town centre, and in Bristol a third of the streets still keep its paving. On listed work, in a conservation area, or in any project that has to match what is already there, the right stone is genuine Pennant, and it is still being supplied. Our proposal applies to new-build work and to projects looking for a blue-grey sandstone with these figures and a European own-quarry supply chain.
Two blue-grey lithic arenites
Both stones are lithic arenites, sandstones made of rock fragments, and both have that blue-grey tone associated in the UK with well resolved public realm. The difference shows up in water. Pennant declares between 2.50 and 2.60 % absorption; Northcliff Blue declares 0.80 %, both measured under the same European standard. It translates into less water inside the stone in freeze-thaw climates, and less room for staining in trafficked areas.
The figure you need to calculate a cladding system
In paving, stone works in compression and against wear. In cladding and ventilated facades it works in bending and, above all, at the point where the anchor holds it. Northcliff Blue publishes an anchor breaking load of 2,050 N tested to the relevant European standard, and a flexural strength of 23.3 MPa that rises to 24.9 MPa after 56 freeze-thaw cycles. Pennant declares a flexural strength of 15.5 MPa as a characteristic value, dropping to 12.9 MPa after those same 56 cycles; an anchor figure does not appear on its published datasheets. If your project is a facade, having that tested value lets you calculate the fixing with the declaration of performance in hand.
Frequently asked questions
Does Pennant have supply problems?
No: Pennant is still quarried as normal. This comparison answers a different need: projects after a blue-grey sandstone with lower water absorption, with the anchor figure published for facade work, or with lead time and availability confirmed per project from a European own-quarry source.
Is Northcliff Blue suitable for ventilated facades?
Yes, and this is where the comparison is most favourable. We publish an anchor breaking load of 2,050 N and a flexural strength of 23.3 MPa that improves after 56 freeze-thaw cycles. Tell us the format, thickness and intended anchoring system and we will send the full declaration of performance for your calculations.
What if my project needs the slip resistance figure?
Ask us for it before deciding. Our declaration of performance publishes slip resistance without a breakdown by finish, and flaming is precisely the finish that improves it. We will send you the laboratory-confirmed test so you can decide with the figure in front of you.
Check availability and lead time
Weighing a blue-grey sandstone for your project? Tell us the m², format and target date in the message and we will prepare Northcliff Blue availability, lead time and price with real numbers.
- Availability, lead time and price with your measurements
- Physical sample free of charge for professionals
- Technical datasheet with test values