Victorian cottage with an early 1900's extension built against a granite stone retaining wall against granite hill... soaking wet.

[erol_flow]

Hi,

The place was left empty for a year with no windows opened etc.

I have attached before and now photos showing the wall covered in tiles and my progress of taking it back.

My idea is to take it right back to the granite stone retaining wall and see how workable it is as it is. I am also aware that I may be better off tanking but i'd like to see how this goes first. A side note, there is an upstairs room which is the bathroom. It has a stud wall which is dry. There is a vent which when removed revealed plenty of draft airflow behind there and lose hanging sheet of plastic material, don't know what the wall is like on the other side, i guess i should have a look but haven't got that far yet, also not sure if i'll ruin what does not require fixing, but if its so wet on the wall below then perhaps it is part of the same issue.

The retaining wall extends above the extension and has been cemented in, i assume this is stopping the wall from breathing maybe?

Around the footing of the property has all been cemented in and so i'll dig one of those French drains in too.

My hope is that wall once stripped back to its original granite wont be too bad to live with as it is, and i can cover it in moisture reducing plants and allow plenty of air flow and some dry heat from the fire place (in the next room) might help.

My other option is tanking but i'm not too sure. Any experience, thoughts, advise, ideas or questions much appreciated!

Thank you for reading


cemented at the top of that retaining wall
the inside ground floor
after removing some material, the tiles pulled off very easily from the damp wall, the lower part of the wall (not tiled) was not very damp.
Partition wall with neighbour was soaking wet, i guess ingress from the retaining wall, strange that it was all over though (compared to the main back wall which was not drenched below the tiles, however maybe down to it not having any damp proofing, there is a whole load of holes at the bottom of this wall which suggest some injection damproofing applied in the past)
this is my own interpretation of the layers that have been used to cover the internal side of the retaining wall, the hole in the middle is the granite stone.

To add to the fun, there also seems to be 4ft high arch bricked tunnel in this wall which was covered and infilled with white sand. Strange but would be great to bring it back.

 

[erol_flow]

Hi again, I've done a fizz test on the white stuff with vinegar and it is indeed fizzing back positive as lime. I'm just very curious about what the layers beneath could be? There's around 1mm of this slate like layer, then about 10mm of sandy mortar (this looks like sand coloured mortar from modern buildings), then beneath that the retaining wall (this one bit in the photo is the red brick section of the retaining wall).

Any help identifying what these layers beneath the lime are much appreciated, I don't understand why they used lime ontop on these solid seemingly non breathable materials.

Many thanks!

 

[aockenden]

Maybe it was done during the transition period between cement and lime? And they started doing backing / scratch coats in cement but the plasterers still liked the "creaminess" of the lime for the skim layer on top? In any event, if you're trying to properly dry the wall out (to whatever extent possible in this situation) and you're quite sure there is a layer of cement on there, you would probably be best advised to strip it all the way back to bare stone and re-plaster with a lime-putty based plaster.

If you wanted to get some insulation on this wall which has a high possibility of being damp over the long-term (due to it being a retaining wall for soil), you could use an insulating lime putty plaster with a non-biodegradable insulating aggregate (perlite would probably be the best bet) to do the scratch and float coats (2 cm thick each, applied directly onto the stone). Then a standard lime putty + fine sand skim coat on top to finish. In this circumstance I would be worried that other insulating aggregate options (like hemp or cork), or breathable insulating board options (like wood-wool, cork, wood-fibre) would be subject to mildew / mold over time as the wall may never fully dry out.

 

[erol_flow]

Maybe it was done during the transition period between cement and lime? And they started doing backing / scratch coats in cement but the plasterers still liked the "creaminess" of the lime for the skim layer on top? In any event, if you're trying to properly dry the wall out (to whatever extent possible in this situation) and you're quite sure there is a layer of cement on there, you would probably be best advised to strip it all the way back to bare stone and re-plaster with a lime-putty based plaster.

If you wanted to get some insulation on this wall which has a high possibility of being damp over the long-term (due to it being a retaining wall for soil), you could use an insulating lime putty plaster with a non-biodegradable insulating aggregate (perlite would probably be the best bet) to do the scratch and float coats (2 cm thick each, applied directly onto the stone). Then a standard lime putty + fine sand skim coat on top to finish. In this circumstance I would be worried that other insulating aggregate options (like hemp or cork), or breathable insulating board options (like wood-wool, cork, wood-fibre) would be subject to mildew / mold over time as the wall may never fully dry out.

Thanks, thats a good idea about the perlite.

yes that does make sense about the wall being done during a transitional time.

I am definitely going to carry on in the morning with the process of stripping back to rock.

The floor above this has a stud wall with a plastic membrane and plenty of airflow in the cavity, its vented along the side and into the room and the stud wall is dry.

I am wondering if I am being overly adventurous in not simply creating the same situation below...

I've seen wood fibre boards that can be used to partition and apply the lime plaster too.

Either way I'll take it back to stone, shove an industrial dehumidifier in there and see where I go from there.