Strange damp patch

[DaveHobson]

I have a mysterious damp spot in our Bailey Advance 66-2. It’s near the rear corner, as shown in the photo. It gives a reading of 25-ish, and is very small, literally as shown by the red outline. The reading gets lower right in the corner, and is negligible in the rest of the bathroom. Anyone care to hazard a guess as to the cause? It’s not surface moisture, nor does it seem to be related to rainfall (reading stays the same in wet weather). Rather mysterious!

 

[Swifter]

Poor toilet aim could be the problem

 

[fat haggis]

Looks like a twin jet abnormality.

 

[Just smiffy]

Could be a spot where there is no insulation underneath so could be a spot of condensation..

 

[PP Bear]

From the photo, there looks to be other dark spots, besides the one in question, are the readings different across the side of the floor.

As Just smiffy said, could be colder areas from different level of insulation

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[DaveHobson]

Could be a spot where there is no insulation underneath so could be a spot of condensation..

That sounds possible - just wondering why there would be no insulation in that one spot?

 

[DaveHobson]

From the photo, there looks to be other dark spots, besides the one in question, are the readings different across the side of the floor.

As Just smiffy said, could be colder areas from different level of insulation

No, I think the photo is misleading. The shading is part of the vinyl flooring - the readings are uniformly low everywhere else - on the other side of the toilet, under the washbasin, etc,

 

[Shrimp]

Could it be run-off water from the basin after washing?
If we are at a certain angle, after washing there is usually a small puddle in a certain area.

 

[The Wino]

It could be run off from condensation on the plastic trims along the floor to wall and wall to wall joins. If the area is largely plastic and vinyl it could be it takes ages for any moisture to go.

 

[DaveHobson]

Could it be run-off water from the basin after washing?
If we are at a certain angle, after washing there is usually a small puddle in a certain area.

Thanks, good idea, but it’s so consistent - been there for months - so I don’t think so.