Friday, 26 October 2012

Roman Box Flue Tiles AD 43- 410

The last few posts have been dominated by the Georgians, so time to go back to the very old. Over the last year I've slowly built up a small collection of largish chunks of tile with rather attractive, simple indented patterns. It was time to work out what they were from. 
Mudlarking Finds: Large Chunks from Roman Box Flue Tiles 
Satisfyingly old, the Portable Antiquities Scheme database helped me identified their origin, Roman box flue tiles. Took me a little while longer to work out what this meant. They were used in Roman Baths and villas. Essentially a hollow box with two open ends, made of clay. They were placed one on top of the other in the walls and  carried hot air from the under floor hypocaust system into the roof and then outside, heating the inside walls on the way. 
Roman Bath House showing Box Flue Tiles rising in the wall (University of  Leicester) 

The box tiles had grooves cut into them on one side 'keying' so that more 
wall plaster could adhere to the tile, thereby improving the strength of the 
bond with the wall. Now I look more closely at my finds I can detect traces of 
white mortar, but perhaps I'm imagining. Patterns were applied to wet clay 
with a roller stamp or a comb. It's strange the patterns are so beautiful and 
carefully applied given they'd be completely hidden in the wall. The same 
patterns have been found at different locations in England, suggesting that 
tile makers moved around. 

What's interesting is the difference between the tile fragments. There seem to be three sets. The first have diagonal deep cut grooves similar to the pattern in the picture above. A combed pattern seems an apt description for the second set. The last tile is rather different, thinner with shallow wide indentations. I'm rather excited on discovering that there was a bath house not far from where I found these tiles, perhaps they originated from this? But then again why don't they have the same design? I guess the Thames may well have mixed things up along the foreshore after 2,000 years. A map (from Britain Express) and reconstruction (from Museum of London) of Roman  London below. 


  1. I've just found some of these in the Pitt-Rivers museum founding collection - very useful blog post, thank you!

    One of my pieces also has white mortar adhering to the tile confirming its use.

    In case you want to have a look their accession numbers are (1884.140.1501 .1-3)

  2. I find these too. some have random comb marks. people tell me this was to key plaster to them. So these were IN the wall proper.
    Some are elaborate decorated and would be flush on the wall surface to show the decoration.

    The Romans were a savvy bunch, I have a hunch that they new a regular flat surface heated less. So my theory is that some bold comb lines were added to put more heat into the room - use less fuel.

    1. Interesting theory, thanks for sharing it, Julia