If anyone is still following this.... 'Matildas Blanket' is an insulation system made near Port Talbot South Wales. The product is an insulated wall system for internal fitting (as opposed to eternal wall systems, often referred to as "cladding"). And different to cavity wall insulation which is fitted in-between the internal and external walls usually by injection or blowing the insular product into the cavity.
There are few building structures which cannot be insulated by one or the other system. There is a huge amount of urban myth, misinformation, and absolute dribble which come from the cohort called "...they..." who seem to know everything despite having learned nothing.
Let's get one thing right from the start - Cavity walls do not need to breathe.! The cavity is there to make the house walls which are seen on the outside pretty - the internal house wall which holds up the roof is not pretty at all, and its an extra layer of protection to the inner wall.
So having decided which form of insulation you wish to use for your house - and all house walls of existing stock (not new from about the 1980's which will be at least partially insulated as building regulations since then have demanded it) can be insulated. Some exceptions such as listed buildings conservation areas etc will have an impact on what you may do. Your Planning Officer of your local authority can advise. Remember your Planning Officer is your Public Servant funded mostly from your council tax, so use them for good advice.
Not insulating your house will lose you heat and create a large energy bill. Imagine going out on a cold winter's day without a coat jacket or jumper. Thats what an uninsulated house is. Insulating it, simply speaking, is putting on the coat or jacket.
Insulating the house works both ways too. Its easy to think its all about keeping warm -but just think back to the scorching heat of just some months ago - what would you have given to cool your house down. Wall insulation is dumb! it does not know which way the heat is going, so when its very warm on the outside, the insulation will partially retard the outside heat from heating up as well - it works both ways.
It DOESNT MATTER what insulation you use, whether internal external or cavity you have - but it goes hand in hand with ventilation -a massive problem in the UK. No matter how much you think you ventilate your home - you are doing it only about 10% of what you actually need to do. How can you heat up your house and keep it warm by ventilating it as well - the simple answer is - its impossible, - but that doesn't stop the need to try. There are now clever devices which ventilate well but claim back the heat energy inside the air being expelled to preheat the fresh air bring drawn back inside. Ventilation is critical to what we refer to as INDOOR AIR QUALITY "AIQ"
I am a housing surveyor looking after around 4000 houses as part of a small team - and we face these issues every single year. I use a range of tools psychrometer/ temperature and humidity dataloggers, hygrometers hooded anemometers and so on and so forth in our daily job. This winter most houses humidity has been in the range of 60-28% average where two three have been at 99% -yes water running down the walls. -poor ventilation + children or elderly or lung conditions = bad bad IAQ. But as a housing specialist (not I'm not an expert) in this area of work - my own house throughout the winter months the temperature has averaged 22C with a humidity (RH%) of between 39-50% - almost no risk of condensation mold or damp. If anything, slightly on the dry side which is the excuse to always have lovely flower displays in vases to keep the room more humid. The house was designed to be on the dryside, and so good knowledge and application of learning is the key.
So, get accurate information from experts. Don't listen to the cohort of "..they.." who know everything from insulation to cures for snoring and how to stop the flan from flopping in the oven!
Talk to manufacturers - they're literature is freely available on their websites. Even have a look at Matilda's blanket. I have - twice. And now for the first time we are going to use it to insulate two external walls of a very cold bedroom. The beauty is there is no "wet trades" after initial survey - the product is made to size in their factory and delivered to site. Header and footer rails fitted to floor and ceiling, and once erected, installed completed and decorated -in just a few days - you would never know the works had been done - and its now insulated. I'm installing data loggers into the room for 2 weeks before, and will re-measure it for two weeks afterwards (taking into account the OAT (outside air temp) That extra increase in reduction of heat loss I have no doubt will lead to one resident next year not ringing to say their bedroom is too cold...
But ventilation ventilation ventilation - the three most important words in anything to do with a house. If you want to know why... go buy yourself from Poundland or Home bargains a couple of those little plastic dehumidifiers for about £1.20 each and place them in the coldest corners of your house. OR, if you suffer from water on the bottom of your windows in the mornings -go and surprise yourself. Do this - leave that window open at night - all night for ventilation (ajar, locked) and leave your bedroom door open or ajar. Then next morning have a look at the window - I bet you a quid you will not find anything as much water as the day before!
As a final note - if you do have black spot mold growth - it doesn't clear itself away. Once it starts - it will continue. So clean it immediately. A little white vinegar (mild acid) in water and a good sponge and elbow grease - even if it takes a few goes. NOTE - Wear rubber gloves and a face mask and always follow manufacturer's directions. But once its all gone -its like the cooker hob. If you don't clean it regularly it will build up again. It contains bacteria not good for children, elderly or anyone especially with lung conditions or asthma.
So warm house - insulation but for a warm & healthy house -insulation and ventilation. Don't listen to the idiots who are the so called "...they" Get good clear advice, understand what makes a building work and read manufacturer's information. For some really good advice if you can get there is the National Homebuilding and Renovation Centre in Swindon, just off the M4 motorway.
You can easily spend a day there if you are really interested in things like insulating your home and other improvements. Lots of experts. Cafe, exhibition stands - all year round and if you book in advance probably free as well. You can even see what a Heat Pump is and does.
I hope at least one person reading this will gain something, but I feel sorry for those who look for genuine good advice and get rubbish. from the "...they..." group of people. Get to the source. Use CAB, Energy Saving Trust, Local Authority, National Homebuilding Centre, Practical Building Magazines, the BRE (Building Research Establishment) There's plenty of not-for-profit organisations out there to learn from so use them - Good luck and enjoy Matilda's Blanket if you choose that too.