Moisture in Latex / Screed

[OneSmallThing]

Hi,

We are doing the final parts of our renovation and unfortunately had a leak in a stud wall due to a faulty join that we think went overnight the first night the boiler was left on. It has left the patches of wet you see here, so have had to strip everything out and am getting some equipment in to start the drying.

The question it’s raised is as I tested the rest of the screed to try and find where dry started, I was still getting relatively high readings. I really don’t want to have to take the whole floor up as it will likely delay the project by weeks, but wondered if anyone knows what an OK reading is? When I use my pin type monitor it is saying around 23% in the areas that aren’t impacted by the leak, but I’ve heard those aren’t great for latex.

The RH % looks below 75% (just), which if heard was the sensible limit, but would really welcome some advice as the whole reason for the renovation was because of a leak!

Any help really appreciated.

 

[opps]

I am not a authority. Over the years I have released that damp meters are unreliable when it comes down to plaster/cement which has become wet after curing. My lay understanding is that the salts in the substrate will provide false readings even after the moisture has evaporated. Timber- yeah, bang on.

Far from scientific, but I will either gaffer tape some silver foil over an area to find out if it is damp, and on occasion, dab some wallpaper paste. If the paste is tacky a day later, it suggests that there is a damp issue.

 

[OneSmallThing]

Thanks opps, really appreciate it. The initial LVT tiles around that damp area were very easy to come up, whereas the ones remaining I’d have to forecably remove, which as a layman I’m assuming is similar to your wallpaper paste test

 

[crazydaze]

You need to test the moisture with a protimeter or preferably a hydrometer box.

What do you plan to lay flooring wise in that space?

 

[OneSmallThing]

Hi Crazydave, I think the tool that the chap I had round used is a protimeter - they grey ones in the photo? But he was referring to the MAX REL figure, rather than the RH %, which my online research seems to suggest is the one that matters.

Flooring wise it will be glue down LVT tiles in that space

 

[crazydaze]

If you can get a 75% RH reading with a flooring moisture tester, be it a protometer or ideally a hydrometer box, you are good to go and screed/lay.

If the screed that is down is moisture tolerant, you could consider applying a liquid DPM over the floor, something like F-Ball F77 and then final screed over that, no more waiting or wondering.

 

[OneSmallThing]

Thanks so much - have put a condensing dehumidifier and sealed the two areas off with polythene, and already in a day it’s hugely improved, so I’m sure I’ll be good to go in a week.

Thanks so much for the help and advice