Renovating a stone house? Here are the 5 key areas you need to consider for a successful renovation

If you're renovating a house, there's a fair chance it's made from stone. The British Isles has an abundance of stone properties everywhere, from small flint cottages to large stately homes and everything in between, such as old farmhouses and manor houses.

However, every owner of one of these properties, whether it be a homeowner or a larger body such as The National Trust, will be familiar with both the beauty and attraction of using stone, and the pitfalls in owning and renovating a stone house.

The first step in understanding how best to renovate your stone building is to identify if it is an historic building – typically built pre 1919 with solid wall construction and without a damp-proof course, or a modern building – identified by the inclusion of a cavity wall.

In this article, I take a deeper dive into the historic category to help you establish the key points you need to consider before renovating a stone house.

Insulation and thermal performance: How to achieve the right amount

A key consideration in modernising or upgrading an old stone building is deciding what level of thermal performance you are trying to achieve. Although it is possible to increase the insulation levels of a stone wall by insulating the inside of the wall (this is known as dry lining) there are a number of issues to be aware of.

It is important to maintain the breathability of the structure, so any materials added to the inner face of the building need to be breathable in order to ensure that condensation doesn’t build up in the wall construction. Typical materials suitable for this purpose include sheep wool insulation and wood wall board. These materials are not only breathable, but also are sustainable as they are produced from natural materials and are biodegradable.

However, it is important to take a holistic approach when looking at improving the thermal performance of a stone building. The walls are only one element of the building fabric – it might be more beneficial for example to improve the insulation levels of the floor, roof, windows before considering the walls.

It's also important to remember that old buildings do not lend themselves to becoming completely airtight. A level of ventilation is required and necessary to maintain breathability. It is important to identify an appropriate level of performance for the building and to go for the simple wins that are low cost and easy to implement, such as draught proofing windows and doors.

Integrating services when renovating a stone house

As the thickness of stone walls can range from 300-1000mm, integrating services into stone buildings can often be a challenge. Therefore it’s important to have a clear design strategy in place at the outset and can change depending on if you are looking to leave stone walls exposed or cover them with new walls.

Installing services on exposed stone walls

If you are hoping to showcase your stone walls, one design strategy that can be used is to expose the services so they are mounted on the surface of the stone. This is quite an industrial look, but not as easy as it might seem, as if the stone is very uneven then the fixtures may not sit on the surface tidily. In addition your electrician and plumber need to be suitably skilled to ensure any pipework and conduit are neatly arranged and installed.

You will also need to plan exactly what services you need and the exact locations and specifications of sockets, lights, thermostat radiators and plumbing fixtures much earlier on in the construction schedule, ideally at first fix stage. This can be challenging in terms of both design and co-ordination, as it requires extra organisation and, of course, comes at a cost.

Options when integrating into new stud walls

Another strategy is to integrate the new services into any new stud walls or areas that will be dry lined. This is easier to implement than the exposed services strategy but requires forward planning in terms of design to ensure that you have the right distribution of services in the room.

You will need to ensure you have enough sockets, adequate lighting distribution and heating provision. This can prove problematic if you only have one new wall as it can be filled quite quickly, as all the services will be competing for the same area.

Using a combination of new and exposed walls

However, the good news is you don't have to choose one approach throughout the property. Both of these strategies can be used in combination, and for different areas. If you are working with a designer or architect they should be able to help guide and advise you so that your final choices work with the overall design of the building.

When speaking to clients, I always look to highlight key walls that might be exposed, discuss what type of heating might be appropriate, and the lighting design being considering to ensure all these elements can be integrated. On several buildings we have also used a strategy where we have introduced a wainscot detail using half height wall panelling to integrate services at a low level and expose stonework higher up. This not only looks good but helps to reduce the amount of exposed electrical and plumbing.

It is also possible to supplement your service integration by using using the floor. For example, if you are installing a new floor slab you might be installing underfloor heating which will remove the need for radiators. You can also add floor mounted electrical outlets and lighting in order to reduce the requirement for services in the walls.

Structural changes are possible with expert calculations

Stone buildings are generally quite forgiving when it comes to making structural changes as the load paths are normally quite straightforward and stone walls are typically quite deep.

However, the viability and cost of alterations will depend on the individual building, its condition and the way it has been constructed. It is always important to take advice from a structural engineer that is used to working with stone buildings.

The importance of getting your repointing right

If structural changes have been made, or external openings have been altered, then repointing might be required to reconcile the altered area. It is amazing how much repointing a house can alter its appearance – for better and for worse!

It is rare that a house needs to be fully repointed as most historic pointing is actually quite sound, and a lot of the time repointing is considered as a way to tidy or smarten up the appearance of a building. However, this should always be a last resort as often it can give an ‘over-restored’ appearance and erode the character of the original house. Often there is not one pointing type or mortar mix on an older building, but several styles and colours that speak of the phases of development of the building and help communicate its character and history.

Historic buildings were traditionally pointed using lime, sourced and slaked locally, and each area has its own distinctive additives and colours. Lime is softer than stone and therefore provides a sacrificial layer which weathers out. In the 20th century, lime was often replaced with cement which can cause quite a few issues in older stone properties as the cement is often harder than the stone.

If you are in an area of limestone, such as the Cotswolds, it's worth asking your stonemasons or main contractor to prepare a number of lime mortar sample walls in order to show different pointing mixes. This can help ensure you select the right match to the existing one.

It's also important to remember that if the property is listed you will need to obtain listed building consent for any repointing work that goes beyond a small patch repair that might be considered “like for like”. The conservation officer will want details of the pointing mix and may also want to see a sample panel to approve the colour and style of pointing.

Retaining and restoring character features

Historic stone buildings are full of character features and one of the challenges can be how to retain or reveal these features, while creating a home that works for modern living. Uncovering an inglenook fireplace for example may feel like a great additon to your living room, but it is important to remember that opening up a fireplace is a structural undertaking. It is therefore worth understanding the value and complexity of the fabric of your home, before deciding what to remove.

As with repointing, if your house is listed, you will need listed building consent to work on fireplaces and the conservation officer will want a detailed appraisal of the significance of the feature and the phases of development, before allowing you to alter it.

Even if your house isn’t listed it can be useful to try and analyse what has happened to the fireplace as it is one area of a house that has often experienced quite a bit of change. Fashions and changes to technology mean fireplaces have reduced in size to be more efficient over the years.

If you decide that you would like to open up the fireplace, its advisable to consult a structural engineer as the load paths may have changed in the fireplace over time. You may need structural interventions, such as the insertion of a new beam or strengthening of the chimney breast, to ensure the fireplace is sound. Opening up these types of fireplaces is hazardous and should always be done by an experienced contractor. Temporary works such as props may also be needed to ensure the structure is sound while it's being worked on. It can also be very messy with soot and dirt pouring out of the chimney and you need to decide if it's worth adding to your renovation schedule or if your renovation costs are best spent elsewhere.

Of course, with the right approach, design team and qualified tradesmen, it is perfectly feasible to alter and reconfigure stone buildings to ensure they are fit for modern living both in terms of their layout and thermal performance.

For additional reading on stone buildings, I recommend an easy to digest book called The Old House Handbook from Amazon which provides a lot of practical advice and solutions to the issues above. In addition, historic England has some very useful technical information available online.

Or, if you're still looking for the right property to make your mark on, make sure you follow the advice in buying a property to renovate to ensure you don't end up purchasing a house that's hiding too many secrets.