Is my wall wet because of the holes in it?

[Mark and Jen]

This may be the dumbest post ever...and I hope it's that simple!

This is the exterior wall to my stone barn. Stone and lime built, few hundred years ago. On the other side of the wall, the internal floor is a concrete slab which is at least 2 feet higher than the floor on the outside. The building is on a slope so they built the internal floor up higher at this end so it is level inside. Anyway, I have recently line washed the inside and there is a spot here where it is not drying at the floor level inside-which is 2 feet high on the outside. So it is not being caused by water coming in/up at floor level on the outside because that is a) dry and b) too low anyway.

So is it caused by water coming through this big crack!! I know that probably sounds like a dumb question to which the answer is yes. But it is a 600mm wall.... with cracks like this in a few other places that are dry.

So, am I being stupid and it is obviously the crack and I just need to re-point that section?

In the pictures you can see the floor level because it is where that power lead comes through and goes off to feed my greenhouse. That power lead internally, is a floor level.

 

[Cubist]

Well, the crack won't be helping and some water will be getting in via that route but... theres a better than even chance that the damp you're seeing indoors is the product of water from beneath the concrete slab being pushed into the walls by a DPM under the concrete. First line of attack though would be to re-point that track in the wall to prevent further water penetration from that route and then monitor the internal situation for any improvement before deciding whether further measures are needed/possible.

 

[Mark and Jen]

Well, the crack won't be helping and some water will be getting in via that route but... theres a better than even chance that the damp you're seeing indoors is the product of water from beneath the concrete slab being pushed into the walls by a DPM under the concrete. First line of attack though would be to re-point that track in the wall to prevent further water penetration from that route and then monitor the internal situation for any improvement before deciding whether further measures are needed/possible.

Thanks for the response.....one of my next jobs inside the barn is to level the rough and horrible slab floor with some self leveling compound.....If the floor itself is dry, any reason not to crack on?

Also - thinking aloud. Right now it's 5 deg and 97% humidity in there (having just done the walls) - Its getting a split unit heat pump installed to bring it up to gym temp 14/15. It will also be ventilated in a better way than it ever was (we only moved here 3 months ago) so am i right that IF its water from under the DPM then with the room warmer and ventilated that moisture might now leave the wall, into the air inside and get vented out? Instead of right now where it cant leave the wall due to the saturated cold air?

In otherwords...fix the crack, heat it up, might be all good! ???

 

[Cubist]

rough and horrible slab floor

Sorry, but I thought you'd said it was a concrete floor? Slab can be a confusing term as it's used to describe stone or concrete pavers at times. If it is concrete is there any evidence of a DPM visible anywhere around the perimeter? If you cannot finding evidence of such or otherwise confirm the presence of a DPM you would be wise to check whether the SL Compound chosen can cope with damp rising through the concrete as it may cause it to split or delaminate.

No need to fix the crack in the wall before heating the space, any loss would be negligible in a wall that massive.

Regarding your thoughts on how heating that space may aid removal of damp from the perimeter walls. I'm assuming you're installing an Air to Air heat pump so the thing to remember is that the warm incoming air will rise toward the upper reaches of the room before the initiated convection currents begin drawing it down toward ground level. As a consequence you may find that any drying effects near the foot of the walls may be negligible and, unless you're using some kind of 'forced' ventilation system that draws cold air from the ground level, the lower layers of air may not be as warm as you might expect.

 

[Mark and Jen]

Sorry - concrete slab....and there is signs of a DPC at the edges inside where it meets the walls. Was planning to use a damp tolerate SL compound just to be safe.