On the project Near St Bee’s in Cumbria we were asked by the client to re-render the front & rear elevations of their Grade 2 Listed home. The stonework had been pointed with a cement based mortar in the past. The client wanted the lime render to be a ashlar lined finished stucco. We first started to remove the cement based pointing for the front and rear elevations. We used only hand tools to remove the cement mortar from the stonework.
All the voids in the stone wall had to filled with a Lime Based mortar prior to applying the render. This is done to even up the stone wall and fill any large voids to ensure a smooth overall finish. For this we used a NHL 2 Lime mortar, which was mixed with a local sand that we had tested to ensure it was right for this project. The lime mortar was tightly compacted into the open stone joints using a packing iron. Our Listed building specialists have worked on many building in Cumbria under taking Lime Rendering & Lime Plastering. The stone on this Listed Building in Cumbria is the traditional red stone sand you get in Cumbria, Chester and Liverpool.
Once the lime pointing has been completed our Restoration Specialist team left it to carbonate for around a week. We erected a roof over the scaffolding to protect the lime mortar from the weather and install mono-flex sheets to prevent the Lime mortar from drying to quickly.
We then applied the base coat Lime Render which is approximately 10mm thick. We used a wooden float over the render to ensure it is compacted onto the surface of the stone. As before with the lime pointing it is vital that the lime render does not dry out to quickly or the lime will not carbonate. Most failure in Lime Render is due to the render drying out to quickly after it has been applied to the brick or stone work.
Once we had applied the lime render to the wall it was covered in Hessian sheets that had been soaked in water for 24hr. The Hessian sheets prevent the new lime render from drying out to quickly and allows carbonation to take place. We normally leave the the Hessian sheets on for around 3-4 days depending on weather conditions.
We then applied a 8mm – 10mm float coat, followed by a NHL 2 lime render top coat. This top coat lime render was applied with a steel trowel and once applied was left for a few hours to harden up. Our Restoration Contractors then used a wooden float to level the top coat lime render and also give a textured finish, before lining out of the ashlar blocks. After the lime render has been lined out we applied a lime wash to give a coloured finish.
The stucco lime render lining out can be very difficult to get correct and also defined lines. We use a lining iron which is basically flat bar shaped to enable the lining out of the lime render to create a stucco ashlar replica.