5. Internal Wall Insulation


Insulating your outside walls, on the inside  (the mother of all home DIY projects)

◻︎   Why? To reduce heat loss on homes that have solid walls, or unfillable cavity walls.

◻︎   External and internal wall insulation are both possible. Internal is cheaper, but you do reduce your floor area. So do your research, talk to suppliers and people who have already done done it.

◻︎    The process is to fix insulation on the inside of the outside walls.

There are a few alternatives:

•Fix solid insulation direct to the wall
•Batten the wall and insulate between
•Build a new stud wall away from the existing wall
•Apply an insulating plaster

◻︎    Research into the available materials and check the manufacturer’s data sheets carefully especially for U values, suitability and safety, including fire ratings (relevant to ‘insulating wallpaper’ – see www.anaglypta.co.uk and follow the links for Wallrock KV600).


Looking for a DIY project – look no further

•You will need to prepare an order of works and identify what you can tackle yourself. Remember some tasks will require a second pair of hands to be done safely.
•You will need to coordinate other trades and use their time responsibly – you do not want to annoy your plumber/electrician/plasterer by calling them back for small tasks which could have been lumped in with a larger task if only you had thought it through!
•Remember the radiators (normally fitted on outside walls), electrics, skirtings, door architraves, etc  as well as bathroom, kitchen and bedroom fittings will all need to come off the outside wall because you will be bringing the face of the wall forward. This means isolating electrical circuits, draining down radiators etc so it is not for the faint-hearted!
•A huge bonus is you will be able to close off those air pathways which allow room heat to escape, for instance underneath the skirting boards. All that leakage through the outside walls (fabric loss) should really reduce.
•If you are doing some of this yourself you will need to research a couple of technical things carefully ie
•(1) dew point & vapour barrier
•(2) insulation continuity


Do remember that you will lose floorspace along the outside wall – not a lot, but it can be critical. Also on larger properties which are valued on a ‘per square metre’ basis a market valuation could be negatively affected (perhaps even offsetting the value of the improvements you’ve made), so check with an estate agent.

Tackling internal insulation using a room-by-room approach makes a lot of sense if you are going to modernise (perhaps via DIY) the house over a period of time anyway.

To start your research try:

Energy Savings Trust report – internal wall insulation

Ofgem – Energy Company Obligation (ECO scheme) for possible grants