I am thinking of buying a 1970’s bungalow it is timber framed with brick exterior. The floor is suspended joists with way roc covering. The owner has no idea if there is any insulation in the walls or floor. The roof is insulated and the bungalow has UVPC double glazing about 15 years old. Is there anyway to bring this building up to modern standards of energy efficiency? The site is spectacular but subject to strong winds.

  • Tony Taylor


    You have lots of options, which ones you choose to implement will depend largely on your budget. The first thing to spend your money on is insulation, and lots of it. Insulation can have a big impact on the energy efficiency of homes and it has the benefit of being a capital cost only (Supply and installation) with very little maintenance or servicing requirements.

    A 1970’s bungalow has probably got cavity walling, although this may not be the case with timber frame construction? Speak to your local insulation company, most will carry out an assessment of the property and advise you on costs for each particular solution, usually with no ‘up front’ cost for providing the quote.

    Triple glazing would be a good option, again speak with your local suppliers to get a free quote.

    I realise this may be difficult as you are only thinking of buying at this stage, however most companies will be able to give you an estimate or ‘ball park’ figure for their services.

    Air tightness is another issue that can be addressed fairly easily and items like new windows and external doors will help improve the current situation. The infiltration of cool air (from outside) and the consequential loss of warm air from the property can add a significant cost to your annual heating bills.

    I firmly believe that zero running cost products and solutions should be given preference over equipment and devices that use energy to save energy, such as heat pumps etc. While these items clearly have their place, it is much better to install something now for a one off cost and never have to service it, maintain it and pay for energy to run it!

    Energy, or more accurately the cost of energy is volatile and subject to change at any time, better to avoid the risk of energy cost increases altogether if possible.

    I am currently working on a project which will achieve the Passivhaus standard, this dwelling has very high levels of insulation and meticulous detailing for air tightness. This results in a heating demand for the whole building of 150 watts, compared to a similar sized property to current Building Regulations requiring in excess of 20 kilowatts, quite a difference.

    Hope this helps, let me know if you need any further details.

    WR3 Design

  • Vince Holden - Construction Project Manager Holden

    Back in the 70s there were very few Timber Frame manufacturers, in fact I know of only two at the time.
    If its a bungalow then it is quite likely a "Guildway", the Cedar timber gable panels was always a givaway. Should you feel that this is the case, then I have many fond memories of working on nothing but for twelve years and would gladly share my knowledge of their construction properties.
    Anyway, if it has a brick outer skin, then there is almost certainly a cavity, however with timber frame construction you cannot cavity fill as an option to increase the insulation thermal value. The external walls will already have a reasonable U value and airtightnes which is not easily improved on without fairly major works, so i agree with tony that the obvious way forward is to address the windows.

    Vince Holden
    Construction Project Management.
    Holden Management Services

  • Tim Pullen

    It will probably come as no surprise that I do not wholly agree. 15 year old douoble glazing is probably passed its useful life but unless there is condensation between the panes there will be little energy saving in upgrading to triple glazing. If we assume a 3-bed bungalow and that the U-value of the exisiting windows is 2.8W/m and that triple glazing will get that down to 0.8W/m that will give an energy saving in the order of 700kWh per year (obviously that is only a guestimate). If you have oil-fired heating that is worth around £45 per year. At that rate it takes a long time to get the price of the triple glazing back.

    Insulation is the key and be prepared to strip out the internal wall boards and floors. A messy job but the only way to effectively install insulation. A 1970’s timber frame almost certainly has glassfibre insulation in the walls – very common at that time – but not much of it. It will be best to take that out and replace with a rigid foam (kingspan or Celotex) to the full depth of the timber studs (as a note natural insulation will give a poorer U-value but will help preserve the timber frame – may be worth installing both). As Tony says, you need to pay meticulous attention to detail in air-tight sealing the joints in the insulation, between insulation and timber stud and pipe or cable penetrations with an air tight mastic – Pro Clima or similar.

    Take a similar approach to the ground floor. If it is a suspended timber floor be sure to leave sufficient of the joists exposed (usually 25mm) below the insulation to allow good air circulation.

    You need to aim at 270mm quilt insulation in the loft or 150mm rigid foam. If it possible to use a loose pellet insulation in the loft, think about Warmcell – very cheap at the moment and at least as good as Rockwool.

    If you do all that you will be a least meeting current building regulations standard, possibly a bit better.

    My view on these things is to spend the money where it is most effective and glazing is the least effective way of saving energy.

  • David P

    Thank you David,Tony and Vincent. It seems like a huge job to remove walls and floors and may not work in the budget because the property is in, to quote the Estate Agent "Good decorative order" and is priced quite high.
    I will try to get some rough guide prices from insulation companies. I imagine you would have to install some sort of sub floor battens to support the insulation 25mm above the bottom of the joists.
    Are properties with suspended floors something to be avoided?

  • Tony Taylor


    Sub-floor battens would be required, as suggested some 25mm above the bottom of the joists, to hold a Celotex rigid foam type insulation board in place. Mineral wool type insulation is quite often installed by stapling a plastic mesh netting to the joists and laying the insulation in place, either option requires removal of a substantial portion of the existing floorboards.

    I am not sure whether suspended floors should be avoided, at least you have the option of improving the insulation in the floor, whereas with a solid floor the whole process becomes a lot more time consuming and costly.

    WR3 Design

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