Anyone used TIWI isotherm

Hello, I have an efflorescent salts and plaster staining on a loft conversion wall directly below the chimney stack. No damp protection was used when first done. One company has suggested wykamol Iso therm thin internal wall insulation. Has anyone any experience of this.
Alternative is to chemically dpc the chimney stack

Have you found the site of water ingress?

The moisture is coming from the chimney stack. Before the loft conversion it would have simply evaporated in the loft, but now the wall is plastered. The wall is separated by a stud wall, under the stack, between stairs in solid plaster and bedroom in PIR backed plasterboard. The plasterboard side has no problems. I cannot have a thicker plaster method on the stairs side as the stringer is already fixed to the original wall.

Well used brick chimneys are notoriously hydrophilic. The dampness could be originating in the air of the living space. I suggest that the origins of the damp be fully investigated by a suitable consultant independent of any seller of “solutions” so that the results are not skewed to a particular product. Over the years many millions have been wasted on unnecessary or even detrimental damp proofing works.

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I put a hat on mine and redid the pointing and flashings. You would be surprised how much water fell into the chimney. I think this was less than £30 to buy.

It looks as though your chimney is still in use. Mine are covered with a much lower fitting cowel so as to reduce ingress from wind blown rain.

I do still recommend the investigations I described above, particularly if the chimney is already weatherproofed in some way.

A follow up, Found a roofer who was prepared to look properly, and it turned out that a piece of lead was missing, called a saddle that sits over the ridge beam. That seemed to work on it’s own but I already had safeguard stormdry sealer so this was put on the chimney stacks.
Is now dry even after some bad rain. so it’s ready for plastering with restoration plaster.

Stormdry is not really a sealant as it allows the wall behind it to breath. That is the key to what you need, not just watertight but drying out too.
Good luck with the chimney, it looks as though you have taken the correct remedial actions and precautions.