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Solid Wall Insulation – Ins & Outs

There is a lot of media attention around Cavity Walls and the benefits of having Cavity Wall Insulation injected into the cavity gap in a property. It is regarded as one of the biggest energy saving areas that can be undertaken on a property and is the focus of many subsidised schemes and grants around the country.

That’s all fine for Cavity Walls, but what if you have solid walls? Are you excluded from having any form of insulation on your property? Well, the answer is no. There are types of wall insulation available to people who have a Solid Wall property.

First off, what is a Solid Wall? There are many types of solid wall out there. Solid Wall can be brick, concrete or stone, or just any material where the entire wall is solid with no gaps in the structure. If you aren’t sure if you have Solid Walls we would always advise you to get professional advice to confirm if it is or is not.

There are two types of standard Solid Wall insulation available and these are Internal and External Wall insulations. If you are undertaking this type of insulation you will have to seek the relevant permissions and you should ensure that the works, if permitted, are done to the most recent building regulations approval.

Internal Wall Insulation

Internal insualtion involves battening out the internal walls to a minimum depth of 50 millimetres or two inches. Within this battening there will an insulation lining placed, normally some form of waterproofing, to stop the transmission of moisture from the outer solid brick to the insulation. There are many types of insulation from rubberised foam boards to fibrous insulation. Once everything is in place and correct then plasterboards are fitted to the battening and the room is available to be used again.

So what’s the benefit of Internal Solid Wall insulation? Well, obviously, primarily the insulation will help to prevent energy loss through the walls, helping to cut utility bills, save money and keep the property warmer for longer. This might be the only type of wall insulation open to you in a conservation area.

The downside is that you will have lost some internal wall space from all the external walls in the property. You will also have to be careful with the hanging of pictures and internal decorations, to make sure they are securely attached to the battening, not loose on the plasterboard.

External Wall Insulation

This process is very similar to the Internal Wall Insulation, involving fitting a frame to the exterior of the property and placing insulation inside. There are various different types of both external insulation and technique, but the end result is that the original outside is covered with insulation and there a new outer weatherproof skin, which normally simulates either brickwork or pebbledash.

The External Insulation won’t continue right to the ground, there is a gap between the floor and the start of the insulation, sometimes several inches, to prevent covering the damp course, or obstructing drainage. Because there is now an external frame over the property, the windows will tend to look ‘set back’ compared to normal windows, but that is normal for External Wall Insulation. There may also be some remedial roof work needed, including guttering and services movement, to ensure the External Wall Insulation is correctly installed.

The benefits are identical to the internal insulation. It provides thermal efficiency savings throughout the property. Again building regulations approval and, probably, planning permission will be required before this can be agreed. The level of work involved should really only be undertaken by those professionally qualified to do so. They will be able to ensure the work is completed to the correct standard and issue warranties and guarantees!

Overall, the negative with Solid Wall Insulation is that it just isn’t as simple or inexpensive as Cavity Wall Insulation to install. Some schemes may offer subsidies or grants towards Solid Wall Insulation but it is labour intensive and it will by necessity cost more. Costs may come down slightly over time but it is never going to reach the levels of the current values of Cavity Wall Insulation, plus you will have permanent Internal or External changes to the property.

If you are keen to spend the money to save money on an ongoing basis then Solid Wall Insulation is an excellent idea. However, you will need to commit time and research into making sure that it is right for you. In the long term you will save money and energy in a similar way to having Cavity Walls and that can’t be bad!

Written By Symon Silvester, MD of SAS EPC Limited

10 Comments to Solid Wall Insulation – Ins & Outs

  1. June 15, 2011 at 2:36 pm | Permalink

    In general a good article, however there are some incorrect statements.
    1. External insulation does not require a ‘Frame’ to be fitted and infilled. The only framework require is around windows, doors, at gutter height and at just above damp course level.
    Insulated board similar to Kingspan can be directly applied to an existing prepared surface wall.
    It will be overcoated, generally with a microporous surface coating.
    Many of these coatings can be smooth finish or textured to resemble render. Additionally many of the ‘epoxy’ coatings carry a manufacturers guarentee of up to 30 years.
    Generally there is no work require at gutter level as the insulation stops short of this area.
    It also replicates the uvalues of cavity wall insulation quite closely, dependant on the type installed.
    As far as costs go it can actually work out considerably cheaper to install, is much less disruptive and quicker to install.
    As your article pointed out , internal insulation requires skirtings, architraves, electric sockets & switches and radiators to be modifiied – thes can be significant additional costs.
    When considering solid wall insulation it is as well to do the maths for both systems taking ALL factors into account.
    Insulation is still the cheapest energy saving investment that you can make – and unlike other energy saving measures it pays dividends from the start – 24/7/365 days a year.

    • Brian's Gravatar Brian
      June 16, 2011 at 6:18 pm | Permalink

      Hi Mike,
      I am hoping to purchase a run-down 60’s bungalow from which to create an eco home. I have long thought that external insulation with a crisp white finish is a desired option. I was pleased to see your corrective comments on the ‘Ins and Outs’ article and in particular about microporous surface coatings. I would like to use my skilled plasterer friend for the finish work rather than work through a specialist firm. I would be grateful for any advice you might have on this idea.
      Thanks in anticipation – Brian

  2. June 20, 2011 at 7:46 pm | Permalink

    I have written an article over on my blog regarding cavity wall and loft insulation. Did you know only 57% of the homes in Britain have the correct ammount of insulation? Just think of all that wasted energy.

  3. July 11, 2011 at 9:26 am | Permalink

    Related to the above article…
    I deal with CESP funding (community energy savings programme) which provides funding towards different retrofitted improvement works.
    Solid wall insulation carries the highest available funding from all the different suitable works types, so if this is something that will be happening to your house/property portfolio etc then please get in touch as I can probably help you with some funding towards your works.

  4. Andrew King's Gravatar Andrew King
    July 12, 2011 at 11:25 am | Permalink

    Just a detail point on the internal insulation, vapour barrier behind the plasterboard is to stop moisture from inside the house passing through the insulation layer and condensing on the internal surface of the wall due to the wall being colder with the internal insulation fitted. There are no concerns with this for external insulation as the whole wall thickness is kept warmer.

  5. July 12, 2011 at 12:17 pm | Permalink

    It may be the highest in absolute terms (£750 or so) but grant funding for EWI is by far the LOWEST proportion of any insulation funded support. External Wall Insulation costs around £100 per square metre so unlike Cavity Wall Insualtion (CWI) where the total cost of say £400-£500 is some 75% covered, (ie you pay around £150) EWI costs probably TEN TIMES as much, say £4000-£5000 at least, so the grant contribution of about £750 is at most 15% – pretty puny. I’m not knocking EWI – I’m doing it myself and would recommend it to clients on technical grounds – but no-one should be under any illusion that it is well supported by Government grant in this country. For some reason sticking eco-bling on your roof is much more heavily subsidised – but that’s a whole other story….

    • July 15, 2011 at 9:28 am | Permalink

      In response to Fordie’s grant discussion around available funding.
      CESP funding for Solid Wall insulation is substantial.
      If it can be included within a CESP scheme (the 10% most deprived areas in the country only) then the funding would be a very good amount. If completed with a 2nd works type, say draught proofing or loft insultaion/top-ups etc (which would mean a funding bonus is applied) then you would be talking £1000,s per property, typically 50%+ more of the cost of the works. The funding itself is not supplied by the government, but by the Energy providers due to the CESP (community energy savings programme) legislation.

  6. July 22, 2011 at 9:21 am | Permalink

    great article very good indeed

    very professional

  7. August 23, 2011 at 4:37 pm | Permalink

    This is a great piece which explains the in’s and outs of solar wall insulation. There are so many questions about solid Wall insulation and why the cost of this type of insulation is so much more than cavity wall insulation this piece answers all the questions really well.

    Thank you

  8. ann cunningham's Gravatar ann cunningham
    July 18, 2014 at 8:46 am | Permalink

    I have been told the house we recently bought had foqm insulation and because this has now fallen to the bottom we cannot get insulated as it would cause dampness is this correct.

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