The data concerns the tests conducted to date concerning fibrous plaster material. The dataset consists of tests for fibrous plaster flexural tests and FTIR tests. Test samples were made and tested in the laboratories of the University of Bath. Flexural tests were conducted on rectangular samples which had been subjected to a range of moisture and fungal degradation. Hessian fibres within the flexural samples subjected to moisture and fungal treatments were further tested using FTIR and a peak ratios method was used to compare results with mechanical performance.