Started trying to tidy up my stone shed this morning, however I’m a little daunted by the size of the job 🙁 The ‘plan’ is to remove any loose rendering, re-render where necessary, coat the walls in a damp proof paint before finally battening and insulating the walls.

However, 30 minutes in and removing the lose rendering has got me a bit concerned. Beyond the render the walls are just rubble:

Any recommendations are how to progress with this? I’m doing the work as the building suffers from a lot of damp, in particular, penetrating damp through the walls.

Any photos from the other side, what state are the walls in externally, are the gutters leaking, basically stop the moisture first, so find where is is coming from.
You don’t want to dry line and trap any moisture in.

The other side of that particular wall has been rendered and appears in reasonable condition. The other walls are simply stone.

Here’s the actual building:

Meant to say, I’m planning on doing the roof on the next dry weekend. As it’s hammering down I’d thought I would do some prep work on the inside.

Is the far wall (the one we can’t see) partly below ground, looks like the ground is level with the window cill? If so check land drainage.
Also check the roof junction with the wall as the slates are close to the edge. **EDIT** just seem your comment, try to get a overhang/drip over the wall to get water away from the wall.
Wall pointing looks OK from photo, but depends on what material was used, i.e. too strong render/pointing and the wall may not breath.
Also wonder why use render on the other wall, perhaps damp issues, or just that stone not good quality.
There are damp proofing renders, but ideally sort damp first.

You need to sort out the roof as that’s the main reason why things are damp.
Please tell me you didn’t repoint the front facade in cementitious mortar.

You need to sort out the roof as that’s the main reason why things are damp.
Please tell me you didn’t repoint the front facade in cementitious mortar.

Next dry weekend the roof is being done, hammering down here so doing prep work on the inside. No idea about the pointing, the outbuilding is probably as old as the house which is 140+ years.

Is the far wall (the one we can’t see) partly below ground, looks like the ground is level with the window cill? If so check land drainage.

Yes, afraid so. Not as high as the window cill but a good one third of the far wall is below ground and as you’d expect suffers from penetrating damp. That’s also on the list to sort.

Does all the lose render need to be removed from the wall in the first pic, or just render over it? I’m concerned that by removing the render I’m going to be left with an unstable wall.

Does all the lose render need to be removed from the wall in the first pic, or just render over it? I’m concerned that by removing the render I’m going to be left with an unstable wall.

If the render is so loose that its dropping off then its not providing any significant support now, and the wall is still standing . . .

** I am not a structural engineer! **
If the stones you have exposed are solid and the mortar pointing is OK the wall should stand up! Is the render falling off or are you having to smash it off, if it is hard work it may be taking pointing with it.
But the main issue is the damp, cause of damp and how to let it breath. Traditionally the pointing would have been in LIME (NO cement) and this allows moisture to breath through the wall, subsequent cementitious materials (re-pointing/render) are more water tight, but can cause issues, by holding damp in.
Look at the roof and ground moisture; consider what you are going to use the shed for and how it is to breath and how to insulate. Sorry always lots of questions!
Note that damp walls can take ages to dry out, (dry means to get back to moisture equilibrium), if the shed is shut up more chance of damp not being able to escape, do the windows open to trickle vent? Shed security verses ventilation to consider.
Then it is only a shed! so consider use, maybe consider tanking type render, if this suits your use, but be aware of future damp issues.

if it were my shed (or a paying customer) i would dig a trench and fill it with big loose chippings along the wall that is buried, to a bit below the floor level. then i would rip off all the cement pointing from the outside and re-point in lime (nhl 3.5 is as easy to use as cement, just keep it damp for 5 days) i would then remove internal render, patching up with lime if and where stones were loose. then i would stop work for a few months to allow the shed walls to dry out while ventilating the shed well. only then i would consider internal wall coverings
(i do this for a living, there are other ways, and it is only a shed but that is the correct way to deal with damp in an old solid wall building)

At least the shed looks happy 😆

if it were my shed (or a paying customer) i would dig a trench and fill it with big loose chippings along the wall that is buried, to a bit below the floor level. then i would rip off all the cement pointing from the outside and re-point in lime (nhl 3.5 is as easy to use as cement, just keep it damp for 5 days) i would then remove internal render, patching up with lime if and where stones were loose. then i would stop work for a few months to allow the shed walls to dry out while ventilating the shed well. only then i would consider internal wall coverings
(i do this for a living, there are other ways, and it is only a shed but that is the correct way to deal with damp in an old solid wall building)

Thanks mate, that sounds like the best course of action. Weather is looking good next week so I’m going to crack on with the roof.

Make sure you use a breathable felt on the roof and get some overhang on the sides where it meets the walls. This will stop the water running off the roof and down the walls in certain weather conditions.

I know you’re going to do the roof, but if I’m seeing it right you have a slate roof and the slates don’t have enough lap over each other. You might get away with it if you have felt underneath, but you should really sort it out when you re-roof and that will mean you need a larger quantity of slates. Hope that helps…….

As suggested, I’m going to dig out the earth behind the back wall of the shed as it is below ground level. I plan on filling the trench with stone so that the water drains away before reaching the shed wall. Is it also worth putting a waterproof membrane against the outside shed wall to also help protect it?

Well I would. Heavy duty polythene. And make sure the trench has somewhere to drain to: you might need some perforated pipe run to a suitable discharge point.