Historic Building Restoration

Historic Building Restoration Challenge – An Award Winning Project

With this article, our aim is to present conservation-minded solutions to the most common challenges encountered when restoring old or listed buildings, including:

– A high water table coupled with the absence of a damp-proof course

– Lateral moisture penetration through walls in contact with the earth
 
– Significant salt contamination within the building fabric
 
– Horizontal rainwater infiltration through the solid masonry
 
– The necessity of insulating the building to an acceptable standard without substantially increasing wall thickness.

The Cob House Project

Best Renovation/Restoration Project 2024 Award Winner

The Cob House is a 300-year-old Grade 2 listed converted block of stables, originally serving as the stable block to Steanbridge House in Slad, nestled in the picturesque Cotswolds.

 

This project was approached as a conservation endeavour, with the client’s primary focus being the preservation of the building’s character while bringing it up to contemporary standards fit for the 21st century.

Listed Building Restoration

However, shortly after commencement, it became apparent to the architect that certain aspects of the project posed greater challenges than initially anticipated. The lime plaster applied to the walls began exhibiting discolouration and crumbling in various areas, mere months after its application.

Damp Stone Wall

This is when we got involved.

Analysis of The Problem: dampness and other issues

Through detailed field laboratory analysis, we discovered that there were five main problems to overcome:

 

 

– High water table (as visible from the water level of the pond)


– Sideways ground moisture penetration through earth touching walls


– High level of salt contamination of the building fabric (the structure was a block of stables, where large quantities of decomposing organic matter created significant nitrate contamination)


– No damp proof course (nitrate saturated ground moisture could climb inside the freestanding masonry unchecked, bringing dissolved nitrates up into the masonry)


– Solid stone masonry is exposed to the elements (after a few weeks of heavy rain the stone work could get wet to the degree where some moisture appeared in the inside, causing patches and plaster damage)

 

 

In other words, we were dealing with a structure with excessive dampness problems coming from sideways rain water penetration, sideways ground moisture penetration through earth touching walls, excessive rising damp due to high water table, and large quantities of erosive salts.

Dampness Survey

On-site salt measurements

Accurate specification of traditional solutions and building materials

Mindful of the project’s conservation ethos, the building conservation specialists of team Core Conservation devised a renovation concept aimed at addressing the dampness issues and achieving wall insulation with a U-value of 0.5, exclusively employing breathable lime-based products.

1. 10-20mm MGN Rinzaffo salt- and moisture resistant protective lime base coat (an original Roman recipe from Marcus Vitruvius Pollio ancient Roman architect)

 
2. 50mm of high performance insulating lime plaster called Termointonaco 2020 (Expanded amorphous microsilica-lime mix, resulting in great insulating characteristics: λ0.043)
 
3. 10mm of AeroGel-lime superinsulating and heat reflective lime plaster (AeroGel-lime mix, resulting in extraordinary insulating characteristics: λ0.016)
 
 
Additionally, on client’s request, we supplied a breathable Roman lime floor as well.
 
 
It’s impossible to share all the interesting details about the materials in this article due to space constraints.  However, we encourage you to click on the hyperlinks for more detailed information, which will open in a separate, new window
Roman Waterproofing
Roman Waterproofing

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Supply

Materials have been delivered to site, in sustainable paper packaging:
Aerogel Insulating Lime Plaster

Application

MGN Rinzaffo salt- and moisture resistant Roman base – machine application:

Lime Plastering a Fireplace
By incorporating AeroGel particles into lime plaster, an innovative solution was introduced that offers exceptional thermal performance while remaining in line with traditional lime plastering techniques. Through this method, a wall insulation with a U-value of 0.5 has been met, with a thickness of under 40mm.
 
High performance insulating lime plasters – machine application:
Aerogel Lime Insulation

Roman Lime Floor Screed

Roman Lime Floor Installation
Lime Floor Screed

You can find more information about breathable, heat storage lime floors by clicking here

The Results in Pictures

Charming traditional aesthetics with 21st-century performance capabilities

Listed Building Restoration
Insulating Stone Walls

By employing a blend of Roman Waterproofing techniques and AeroGel insulating lime plasters, alongside Roman lime floor screed, the property was meticulously restored into a cosy and dry period family home.

Lime Plastering
Traditional Lime Plaster

In our understanding of traditional architecture, Roman solutions and materials excel under challenging conditions. Regrettably, the techniques and materials used in Roman architecture are often considered ‘lost technology’; and are no longer in use.

However, this project serves as a compelling demonstration that the wisdom of ancient Roman architects remains accessible and applicable to our historic buildings, yielding impressive outcomes, just as they did over two millennia ago.

Breathable Lime Insulation
Traditional Lime Insulation for the Roof Space

This project exemplifies many of the typical challenges encountered with older buildings, as well as the expectations involved in restoring a listed property to a high-end family residence.

Listed Building Restoration
Restoring a Stone Building
300 Years Old Property Full Refurbishment
Building Conservation Best Practices
 
At Core Conservation, our objective is to establish a positive precedent within the building conservation sector, demonstrating that great traditional solutions are available, even for the most demanding circumstances.

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