External lime render applied

[Norfolkdave]

Hi all, this is my first post so forgive me if some aspects have been discussed before but I am struggling to find information.

We have a stone built cottage built in 1900 that has had a few sins committed against it, including an external pebble dash render, which we have removed a few months ago. We had this stripped back to bare stone which was in good shape, with original lime mortar, again in good shape. A lime render was applied in a scratch coat and then top coat. One of the reasons for this was high internal humidity.

It has been two months and we havnt applied paint yet, and have opened up what was a sealed air brick to allow air flow. However the internal humidity is roughly the same. On damp days it’s perhaps worse.

The internal walls have been battoned and plaster board fixed away from the wall by a previous owner. This was due to the wall being damp. We have opened this up and put in air vents along the base of the wall so it can breathe internally and externally.

My question is, am I being impatient to expect results in such a short space of time, or do we need to consider lime rendering the internal walls also, rather than just venting the cavity?

Your advice and experience would be appreciated. Many thanks, Dave

 

[aockenden]

Recent weather where we are has been very very challenging, lime or no lime. Outside temps between 15 and 19 with outside relative humidity almost perpetually above 85%, getting as high as 96%. That leaves you very few directions to jump.

You can’t heat your way out of it because outside temps are already relatively high, so even bringing house temp up to 20 degrees will only bring your internal RH down to low 70’s (which still ain’t great).

You can’t ventilate your way out of it, as the outside air is sopping wet.

The only thing that’s keeping our place livable at the moment is shutting everything as tightly as possible and running dehumidifiers.

 

[Norfolkdave]

Thanks for your reply. Yeah we also run a dehumidifier, but would love to get to a place where we don’t need it!!

RH has been higher over the past few days as it is damp, so much for summer. We are hovering around 60, but have previously been low 50’s when the sun is out.

Our walls are around 14” thick, and as the front facing external wall has been wet for around 40 years whilst it had pebble dash on it, I’m guessing we are still drying this out. I live in hope that the lime is pulling moisture out of the wall, and at some point in the future we can get rid of the dehumidifier.

The next move might be vent the top of the internal wall which has been battoned and vented at the base, but not the top.

Weather could do with picking up tho, all the best, and thank you, Dave

 

[a twig]

There are various rules of thumb on here but (depending on weather) for a solid wall it can take 2-4 weeks per inch of wall thickness to dry out (obviously depending how saturated the walls were in the first place, how exposed the wall is etc)

 

[Norfolkdave]

Thanks for this information, the wall in question is south facing so that’s good, it’s been limed roughly 2 months ago so this too will take time to dry out fully, so between this and the wall, I’m probably being a little impatient lol.

Thank you for your input, all the best, dave