Insulation - sloping ceilings in a dormer bungalow

Hi, There are a few options available to solve this problem, you can remove the old plasterboard & fill the voids with either wool slabs or PIR boards cut to fit or if there is enough height you could over board with 62.5mm insulated plasterboard. Unfortunately all of this type of work is quite messy & can be quite expensive also, if it’s just the slopes that need doing it’s best to get the stud walls & any residual loft spaces checked & have those insulated (if required) as to prevent any risk of cold bridging. Cost wise you can be looking at anywhere from upwards of £125m2 to £200m2. I hope this helps answer your questions.

Hi there 👋 Homes like yours from the 60s often have very little or no insulation in those sloping ceiling sections (the “cold roof” void behind the plasterboard), which is why they behave like a radiator in summer and leak heat in winter. You don’t necessarily need a new roof or solar — this is normally solved from the inside. To answer your questions: 1️⃣ Do the existing ceilings need to come down? Not always. It depends on rafter depth and ventilation. If there is enough space to add PIR insulation (Celotex/Recticel) internally and still leave an air gap for ventilation, it can be done over the top of the existing surface. If the void is very shallow, then yes, removal is sometimes needed to insulate properly. 2️⃣ Will it make a big mess? If done over the top, disruption is minimal — boards are mechanically fixed, taped, then over-boarded with plasterboard and skimmed. If ceilings have to come down, there is a bit more dust, but with proper sheeting and extraction it’s manageable. 3️⃣ What type of tradesperson do you need? You’re looking for someone experienced in internal roof insulation / warm roof upgrades, not a solar sales company. Ideally: A carpenter/loft insulation installer used to retrofit work, or A builder familiar with dormer/attic thermal upgrades This is very typical retrofit work now because of energy performance changes. 4️⃣ What’s the usual method? The standard best practice is: Rigid insulation board fitted to underside of rafters Boards taped/foamed to create an airtight layer New plasterboard over the top and skimmed This stops radiant heat in summer, and heat loss in winter. If you’d like, I can assess the thickness of the rafters and voids for you and advise the most suitable system and depth — happy to help with a survey and options if you decide to move forward.