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Most renovation projects involve some degree of insulation improvements (it’s estimated that in the UK 25 million existing homes will need to be insulated by 2050). Thermal comfort and performance is crucial to improving not only the value of your home, but your quality of life while you inhabit it. There are numerous ways to add insulation while renovating an existing property, and here we will focus on wall and roof insulation, as floor insulation (though important, if budget allows) offers less of a return (both in terms of cost savings and performance):
Solid wall insulation – If your property was constructed prior to 1919 then the likelihood is that the walls will be of a solid construction, which unfortunately allows the passage of heat to a greater extent than with a cavity wall. In this instance we’ll discuss stone ‘solid walls’, which are actually mostly constructed from two layers of stonework, with a rubble filled cavity between. Solid stone walls were designed to operate as ‘breathing walls’, and as a result it’s important to ensure that breathability is maintained following the addition of insulation (materials such as wood-fibre, sheep’s wool, etc.). The most thermally efficient method of insulation is to for it to be applied externally to the existing wall, greatly reducing thermal bridging. However, insulating walls in this manner greatly alters the external appearance of a building, and this may not be appropriate for your project (in particular when it comes to period, or non-detached properties). An alternative approach is to add an insulated layer internally to the wall, whilst retaining an air gap to the inside face of the stone (some products such as Icynene do not require an air-gap, as they are open-cell products, which still maintain breathability). This approach requires the re-lining internally of the entire property, and results in a loss of floor area due to the internal line of the walls moving in. It’s important when using this approach (and indeed any method) to ensure that the dew point of the wall has been considered (the dew point describes the point at which air encounters a temperature that causes the moisture it contains to condense and form water), and that interstitial condensation will not accumulate within the wall build-up.
This useful study by the Energy Savings Trust details the issue of solid wall insulation in Scotland (download)
Cavity wall insulation – Cavity walls are usually comprised of two walls (made of brick or block), with a gap between. Most houses built in the last 25 years have some degree of insulation to help retain heat, but as standards are continually improving you’ll discover that the thermal performance of these dwellings is already considerably behind houses built today.
In simple terms cavity insulation fills the gap between the two wall layers, and can help reduce the risk of condensation. Cavity insulation is usually blown into the cavity from the external side of the wall, and requires a cavity of a minimum width of 50mm. In order for a cavity to be suitable for insulation it must be in good condition (ie free from mortar drops and debris), and ideally the walls should not be exposed to driving rain.
Roof insulation – There are two distinct approaches to most roof insulation scenarios, with it possible to insulate either between pitched roof members (warm roof), or between joists at ceiling level (cold roof). Of these a ‘warm roof’ is probably the easiest and most cost-effective of all insulation strategies, with mineral wool rolls being found in most DIY stores or builder’s merchants, and being extremely cheap to buy and install (indeed laying this insulation does not require professional help, and is well-within the realm of DIY). Insulating with a ‘cold roof’ approach is certainly more complicated, as there are many issues to consider, such as the requirement for an air-gap to the back of the sarking board on roofs where a modern roofing membrane is not present.
Most existing houses (but unfortunately not all) will already possess some form of heating system. If this system is inefficient or beyond a certain age this is usually the first improvement that many people consider when renovating a property. Adding or improving central heating will usually result in an increase in value in excess of the capital outlay. In addition to the traditional approaches (such as gas or oil-fired condensing boilers) there are attractive renewables options to consider, such as an air-source heat pump (ASHP) or biomass systems, which when properly designed and combined with thermal improvement methods, can make a significant difference to both the level of comfort and monthly utility bills, as well as attractive subsidy payments through the Renewable Heat Incentive.
In simple terms, an ASHP replaces a traditional boiler as the source for heating water used in the central-heating system. These units operate using a vapour compression cycle (like an invert fridge), drawing heat from outside air. As a result the performance of an ASHP unit is connected to the external ambient temperature, with the difference between this figure and the target internal temperature determining the efficiency of the system. ASHPs can work with radiators if they are properly specified, but optimal performance is gained with the use of underfloor heating.
Biomass systems usually take the form of log and/or pellet boilers when used in a domestic project. The type of timber used has a huge impact on the output of the system, with hardwoods producing considerably more heat than softwoods (the moisture content is also important, with it being crucial that the wood is properly dried). Biomass systems require considerably more user input than most other heating systems, due to the need to consider fuel type, fuel storage and delivery. Running costs of these systems can be lower than other options, but unfortunately the initial capital cost at installation is still relatively high.
Whilst the value of your home is of course important, it should not be the only consideration when it comes to renovating your property. In addition to being a financial asset, it’s important to remember that you are dealing with the place you chose to make your home, and which has an almost unparalleled impact on your quality of life.
There are of course ill-advised routes to follow on renovation projects, which could actively de-value your home, and should of course be avoided. However it’s also important not to be driven entirely by a fear of how an estate-agent may view your home. In many cases (if you find the right agent) we find that the homes we’ve completed are not valued using only a ‘tick-box’ methodology (i.e not all 3-bed houses on X Street are of equal value), and that if real quality has been added to a property this is usually reflected in the valuation should you choose to sell.
Not everyone can be a DIY genius. However if the works on your renovation exceed your own skill set, but are still simple in nature, it can be an ideal opportunity to appoint tradespeople on a package by package basis rather than engaging a main contractor. Renovation projects tend to be better suited to the appointing of individual trades, as it is often easier to break the work into manageable packages, which you can then tender and control, at a pace which suits you (which is even more crucial if you intend to live in the house while works are carried out). This approach allows you to retain complete control over the works, and can be useful when working to a tight budget. It’s worth considering that whilst it’s possible to make savings by going down this approach, there is a reason main contractors cost more in general, due to their experience, organisational ability, and willingness to accept a natural degree of risk on any project.
Appointing a good main contractor allows you to know you have someone in place with the experience necessary to deal with issues as and when they arise (and they do occur with some frequency on renovation projects due to the nature of older buildings). It also allows you to pass the responsibility for issues like site safety and insurances on to a professional, in addition to scheduling and the daily logistics required to deliver a project efficiently. Obviously this protection and benefit comes at a cost, with a contractor’s mark-up being added to any sub-contractor they use or material they purchase. However many clients consider this money well spent, in order to avoid the undeniable stress of running a construction project.
Dust, dust everywhere! Living in a building site can be hugely unpleasant, and there is simply no way to disguise this fact. However, those living on site during a renovation do save money by not needing to rent elsewhere and it depends on a variety of elements as to whether you decide the saving is one worth making or not. It’s important to consider the length of time you expect your project to take (always be pessimistic), and whether the works will be staged to allow for use of your home throughout the process (kitchens and bathrooms tend to be the key areas to consider when remaining living on site). It may be possible to store some of your possessions off-site during construction works, and this is certainly a route worth exploring for items which are important to you.
It’s also of prime importance to consider the insurance arrangements of your property, and you should never assume that your current policy will be adequate, even when considering the insurance cover provided by the contractor to cover the works. Most homeowner policies allow for simple internal refurbishment, but you will need to notify your insurer if you intend to carry out any building work. Most insurers stipulate that any contractors appointed are done so using a SBCC contract, or JCT in England, Wales & Northern Ireland (with the Northern Irish Adaption clauses), but it’s always best to discuss this with your insurer prior to undertaking any works, as situations like this do not always necessitate an increase in your premium.
Renovating a home can be one of the most exciting things you ever undertake. We hope this guide provides useful information, and if you have a project you’d like to discuss with us please get in touch with us in either Aberdeen or Inverness.
