How reclaimed sandstone flags are sourced, cleaned, and graded

Reclaimed sandstone flags have become increasingly sought after for garden and courtyard projects where a new stone would look out of place. The demand is understandable: a well-worn flag has a surface texture and patina that takes decades to develop naturally. But the quality of reclaimed material varies considerably, and the sourcing and grading process has a significant effect on what you actually receive.

Where reclaimed flags come from ¶

Most of the reclaimed flags we handle come from domestic and commercial demolition projects: old mill yards, Victorian terraces, farmyard surfaces, and municipal footpaths that are being relaid. The flags are lifted by the demolition contractor and either sold directly or passed through a salvage dealer. We buy from both routes, but we inspect before we commit to a purchase.

The age and origin of the flags affects their character. Victorian-era flags from urban streets tend to be well-worn and relatively consistent in thickness, having been laid on a sand bed and trafficked for decades. Farmyard flags are often thicker and more irregular, with a rougher surface that suits rural and agricultural settings. We note the likely origin of each batch when we update the availability list.

Cleaning and sorting ¶

When a batch arrives at the yard, the flags are cleaned to remove mortar, bitumen, and surface contamination. Mortar is removed mechanically; bitumen, which is common on flags that were relaid in the mid-twentieth century, requires a chemical treatment followed by pressure washing. The cleaning process takes time and is one of the reasons reclaimed flags cost more per square metre than new sawn stone.

After cleaning, the flags are sorted by thickness and approximate size. Pieces with significant cracking, deep spalling, or structural damage are set aside and not sold as paving. Some of these pieces are useful as random walling stone or fill material, but we do not sell damaged flags as paving stock.

What the availability list tells you ¶

The availability list we circulate to registered clients includes the approximate total quantity in m2, the thickness range, the approximate size range (small, medium, or large format), and a brief note on the likely origin and condition of the batch. It does not include photographs of every piece, because the variation within a batch makes individual photographs misleading.

If you want to see the material before committing, a yard visit is the most reliable approach. Bring your project dimensions and we can pull a representative selection so you can assess the colour, texture, and condition in person. For large orders, we recommend a visit rather than ordering from the list alone.

Practical considerations for ordering ¶

Reclaimed flags are sold by the square metre based on the usable area of the batch. There will always be some waste in cutting and fitting, and the irregular sizes mean that waste is typically higher than with new sawn stone. For a straightforward rectangular area, allow 10-15% waste. For a more complex layout with curves or intricate patterns, allow 20% or more.

Thickness variation within a batch means that the bedding depth will need to be adjusted across the area. This is normal for reclaimed material and an experienced paving contractor will account for it. If you are using a contractor who is not familiar with reclaimed stone, it is worth discussing this before work starts.

The availability list is updated whenever a new batch arrives. If you want to be added to the distribution list, send your name and email to enquiries@aster-sandstone.com and we will add you.