Damp stone wall- is it rising damp?

[KJKJ78]

Hi all,

I'm a newby here so please forgive me if I have the wrong end of the stick....
After reading that damp stone walls are almost always down to what has been plonked on it rather than actual damp I decided to investigate. I have removed the wooden panelling and chipped off all the old plaster including a layer of bitumen from my stone wall as the plaster had blown and was crumbling (I've just bought it so no idea what was done to it previously). Most of it has come off and I'm really pleased to see that most of the wall is dry however, there is a section that is definitely damp at the bottom. it looks to come from the very bottom of the wall but doesn't go fully to the right or left hand side. I hope you can see in the photo the slight difference in colour. So my question is, is that typical or could this actually be rising damp?

 

[sgking]

Could it just be damp that has resulted from the reason you state, I.e that the bitumen has trapped moisture in there? Now that the bitumen has gone it might dry, but it will take some time.

What is the outside like at this point, are there any ways that water could have got in and made it's way down to this location? What is the finish to the outside of the house and what is the level of the outside floor compared to the inside floor?

 

[Cubist]

Two distinct possibilities to my mind. Rising damp from the the ground below that wall but I would expect the distribution to be more uniform unless theres a specific weakness below that section. The other possibility is rainwater penetration somewhere around the window frame tracking to emerge somewhere near that bottom left corner.

 

[KJKJ78]

Thanks both! I think the window is a strong possibility. I just found it odd that all the stone was dry apart from this odd bit. I'll also have a dig around at the bottom where the skirting was and I'll have a dig outside too.
The outside of the house isn't rendered but there is a bit of gravel next to the house.
Watch out for incoming photos as this forum will be my lifeline!

 

[paulc]

Used to have a persistent water leak in my kitchen where a flat roof on the extension joined the original wall. Would only leak during a spell of really heavy rain. Spent quite a bit of time (and money) recovering the flat roof and adding lead flashing, all to no avail. Had a roofer out to quote on other works, and he pointed out a thinnish crack in render just below a window some eight feet away from the flat roof.
Hacked away the render in that spot and discovered a big crack that went right through the wall After stitching the crack inside & out and patching up the render, have not had any more leaks from the kitchen ceiling.

Water has a nasty habit of getting in to a wall and traveling some distance before rearing its ugly head.

 

[KJKJ78]

Ok! So i have scraped the earth (only a thin layer) and gravel away from the outside of the wall. Bits of mortar are starting to deteriorate at the very bottom and there is a hole at the far side (not where the damp is). 1st photo corresponds with the damp showing inside and the second corresponds with the dry area inside. So at a guess, chip of the crumbly bit and replace with lime?

 

[KJKJ78]

There is also plastic liner inside which seems to disappear part way along where the damp area begins.the hammer shows where the plastic disappears.

 

[KJKJ78]

Thank you!!

What on earth do I do about it.......it's a solid concrete floor

 

[Itchinfilth]

Sorry if this has been covered but If the ground levels are higher or level with outside than in, lower it. It could be that it's been getting in that way. The membrane , concrete and modern plaster would have helped keep the damp trapped in the stone as it couldn't dry out.

Search "Zebcolm" on the forum.

I also drilled out the concrete and removed the membrane as damp was travelling under the membrane and impacting other areas (tracking through many meters) but before going to that mammoth effort you may want to see how successful the ground level lowering is first

 

[KJKJ78]

Yes!! I've save the Zebcolm details already so glad I'm on the right track. HOW EXCITING, I love investigating stuff and finding a solution. I can't really tell if the outside ground is higher or lower - I might be being dim but how do I tell if not immediately noticeable?

Plan of action for now is to leave the wall as it is and see if the damp dries out. I'm also having a new window so that could also help.

 

[Itchinfilth]

Measure from the bottom of the window to floor level internally, do the same on the outside and then compare the measurements. The external should be lower than inside. The beauty of the zebcolm is that for the lower courses there is no material against the lower courses for moisture to build up

 

[Cubist]

That plastic liner you've found was/is intended to operate as a DPM under the concrete floor. These can, and do, push rising damp from underground out toward the perimeter walls. If you can find no points of water entry around that window frame then you've found the most likely culprit.

 

[DaveG]

Sometimes, in the interest of funds and your sanity you are better thinking in terms of moisture “management” rather than “eradication”.
Oftentimes you can get to an equilibrium whereby a limited amount of ingress can be managed by reducing ways in which water can get in (like repairing any obvious window issues) and ensuring inside materials are in a state where they are capable of transporting that moisture out into the air.
An example of this is a retaining wall that forms part of a building and has earth from floor to ceiling height on the other side. In this case the earth will always have moisture present no matter what you do but by ensuring good drainage (reducing) and highly breathable materials (managing) on the inside of the wall you’ll find that will often suffice.
Outside ground levels in your case are definitely something you can check and if necessary adjust with relative ease and the same goes for checking wall/window integrity.
Lifting concrete floors however are far more disruptive and costly (take it from me!) so go at it in stages and allow plenty of time, like 6 months or more, to see what impact you’ve made

 

[KJKJ78]

Measure from the bottom of the window to floor level internally, do the same on the outside and then compare the measurements. The external should be lower than inside. The beauty of the zebcolm is that for the lower courses there is no material against the lower courses for moisture to build up

Oh my goodness, I really am dim Thank you! I shall do that.

 

[KJKJ78]

That plastic liner you've found was/is intended to operate as a DPM under the concrete floor. These can, and do, push rising damp from underground out toward the perimeter walls. If you can find no points of water entry around that window frame then you've found the most likely culprit.

Hmmmm, interesting!! Thank you!

 

[KJKJ78]

Sometimes, in the interest of funds and your sanity you are better thinking in terms of moisture “management” rather than “eradication”.
Oftentimes you can get to an equilibrium whereby a limited amount of ingress can be managed by reducing ways in which water can get in (like repairing any obvious window issues) and ensuring inside materials are in a state where they are capable of transporting that moisture out into the air.
An example of this is a retaining wall that forms part of a building and has earth from floor to ceiling height on the other side. In this case the earth will always have moisture present no matter what you do but by ensuring good drainage (reducing) and highly breathable materials (managing) on the inside of the wall you’ll find that will often suffice.
Outside ground levels in your case are definitely something you can check and if necessary adjust with relative ease and the same goes for checking wall/window integrity.
Lifting concrete floors however are far more disruptive and costly (take it from me!) so go at it in stages and allow plenty of time, like 6 months or more, to see what impact you’ve made

Great advice!! Thank you! The damp isn't really that bad so I will investigate all the bits and bobs above and if that doesn't work, management it will be