Damp issue that has disappeared - to tank or not?

[RandomSuitors]

Hello,

I bought a Victorian house that had not been lived in properly for a year or so, leaving it vacant while I refurb it. When the midwinter hit I turned the heating on a bit and a line of damp appeared halfway up a wall. My builders said this was rising damp and that we should 'tank' the wall, but it has since disappeared, even in the very heavy rainfall. What I wondering is: could it have just been something that came once, a sign the house was drying out/heating up? Or will it likely be a recurring problem and I should get it done? It isn't there now, and there wasn't a stain/smell from previous times.

Thanks!

Don't tank it. All that does it trap the moisture in the wall and then it builds up and causes problems later on.
Is it on an external wall? Is the wall lime plastered or is it the pink modern stuff? Where abouts on the wall was the wet line? Near the bottom I assume if the builder was saying rising damp?

And yes it could just be the house drying out but it could also be a slight leak which only happens when the wind blows in a certain direction or one which is to do with snow. We have weird snow ones.

Don't tank it, it'll either trap the water in the walls or force it somewhere else. I'd leave it and keep an eye

It’s an internal wall, last wall of the ‘old house’ before the 1950s kitchen extension was done. That extension was tanked by the previous owners.

Don't tank it, that is not what your house needs, it will make it worse.

There is no such thing as 'rising damp'.

The house needs to dry out from being empty for a while and the heat will have been drawing the water out.
Is it an internal or external wall? What is on the wall inside and out (if relevant)?
Are you mid refurb or living there?

other things, is a pipe leaking somewhere in/behind the wall? Is a gutter blocked? if it's an external wall what is the ground level outside to in?
can you share in and out photos then I can advise more.

I've had something very similar in the past. Moved in just before Christmas and put the heating on in a house that had been unheated for many months. The next day the walls were running water. Condensation everywhere.

We opened windows, kept the heating on low and within a fortnight the problem was 100% gone and never returned.

In your case I think the lack of a smell is a very good sign. I'd bet money it goes and never comes back.

I have had cellars tanked before to create rooms - all it does is redirect water or even trap it.
Finding where water is moving too and from is central to this - if you are on a slope, is it coming down and 'across' the house, with house 'blocking' the way? Do you have drippy gutter on your or neighbours house? Is there a 'soak away' at bottom of drainpipe that is 'uphill' of your house etc? Basically is keep water away from a house.

I have had huge success with putting in French drains against walls, creating a new soakaway with real capacity (removing 100 years of leaves helped...), planting a garden to soak up water or flow it away from house etc.

Edit: you can of course have a ground water spring or similar under a house, but again I put a french drain in a cellar once with a pipe out and it dried the house up so well (not my house, I was doing some building work for them)

From experience, true rising damp is actually quite rare, and it wouldn’t usually appear suddenly and then disappear once conditions change.

What you describe sounds more like moisture showing up when the house was first heated after being cold and vacant, rather than an ongoing defect.

Tanking can sometimes make things worse in older houses by trapping moisture behind an impermeable layer.

I’d keep monitoring for now - make sure external ground levels, drainage and ventilation are sufficient, and only investigate further (with an independent damp surveyor) if it comes back consistently.