Are these damp spots in the lime render signs of impending damage? NHL 3.5, 3:1 sand to lime

[Dace]

DO I have to get a surveyor to find out whether persistent wet patches in lime are a bad sign? I never see patches in anybody elses render when it rains. thanks

 

[Dace]

its a victorian property circa 1850ish build and this is the stone underneath, granite?

 

[Dace]

spent a lot of money on this, pretty mindblown if its starting to fail.

 

[tell80]

The damp spots are an unknown because I dont know how the very rough background was prepped or how the render was applied.
The renders at front elevation and back elevation are different - why?

- You have sand & cement fillets at ground/wall abutment. They need to be removed and then the gap made good but render stopped 50mm above ground level with a plastic Bell Cast.
- The door canopy also has a large lump of S&C fillet - you could leave this in place and flash with lead or remove it & flash with lead.
- The S&C plinths at the base of the wall need removing and the render making good - all render should finish with plastic Bell Casts'.
- The render that stops above the front elevation horizontal band might benefit from lead flashing or even a small S&C fillet. I think a Bell Cast would spoil the effect?
- Cracks can be lightly raked out & filled with polyurethane.
- Your window sills should have drip grooves.
- The RWP discharging into earth is wrong, it could do with a trapped gulley & then piping away.
- Do you show any damp signs inside the house?

 

[Dace]

The damp spots are an unknown because I dont know how the very rough background was prepped or how the render was applied.
The renders at front elevation and back elevation are different - why?

- You have sand & cement fillets at ground/wall abutment. They need to be removed and then the gap made good but render stopped 50mm above ground level with a plastic Bell Cast.
- The door canopy also has a large lump of S&C fillet - you could leave this in place and flash with lead or remove it & flash with lead.
- The S&C plinths at the base of the wall need removing and the render making good - all render should finish with plastic Bell Casts'.
- The render that stops above the front elevation horizontal band might benefit from lead flashing or even a small S&C fillet. I think a Bell Cast would spoil the effect?
- Cracks can be lightly raked out & filled with polyurethane.
- Your window sills should have drip grooves.
- The RWP discharging into earth is wrong, it could do with a trapped gulley & then piping away.
- Do you show any damp signs inside the house?

Yes damp above the middle of the door upstaisr in the new plaster and a crack has formed along the whole height of the house along the boundary between the two. water is entering both houses on either side of the crack.

 

[Odds]

It's been found that the presence of lime in Roman concrete actually helps it stay stronger for longer; even when cracks form in the concrete the lime reacts with the rainwater and provides a natural sealant to stop further rain damage.
@news.MIT
Research is now being done in future applications to include this technique - so, if lime is present in your mix then the cracks should self-heal over time. Since the building has been around for 150 years it should dry naturally, as the original builders intended.