Can a detached, dormer bungalow ever be fully insulated and if so, how? We have had the walls pumped, insulated the attic (apex) floor and installed triple-glazed windows. Is there anything else we can do, especially for upstairs?
Your question is an interesting one. The uncomplicated answer is yes, because very many things are possible when it comes to buildings. With a nice pot of money, the right contractor, and the ability to accept invasive works, you can achieve full insulation.
You could externally insulate your walls, including door and window reveals, grub up your floors and put down upgraded floor insulation. You could remove your roof finishes and insulate your entire roof from the top side. You could open the dormer window cheeks and insulate from outside. Or you could pull down your internal plasterboard from the attic ceilings and walls and insulate and replaster. Or, where you have room, face the surfaces with an insulated plasterboard.
The reality is, however, that where you don’t have the budget or you don’t have somewhere to stay as your house gets a deep retrofit, a fully insulated dormer bungalow may be more elusive.
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So, I suggest that you look at what you can control. You refer to the upstairs, so we’ll concentrate here. You have gone a long way to improving your property, so it’s a matter of stepping back and looking at the detail from the top down. Let’s start with the attic ceiling. You mention insulating the apex of the attic, which I take to be that little flat section directly overhead. Dormer ceilings also have sloping sections.
It might be an idea to open a section of this to see if it is adequately insulated, and if not, consider taking the plasterboard down, insulating and then re-slabbing. This could be done one room at a time. Or, simply assume that there is no insulation and add on an insulated plaster slab to the face of the slope. Be careful not to reduce the head height significantly. Where you can, add an airtightness membrane.
Dormers usually have little crawl spaces or “dead spaces” behind the kneeler walls. These areas can be huge sources of heat loss. You might consider facing these with an insulated plaster slab or, where room is tight, you might have to make a hole in these knee walls to see what’s going on. Often these stud walls are faced with plasterboard but completely devoid of insulation, so you may need to add some.
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The joists in the kneeler space may also be devoid of insulation. Often people think that this is outside the dormer’s heated space because the kneeler walls should be the thermal line, but it’s important to look at the big picture. Devoid joists in kneeler spaces mean that the ground floor rooms are losing heat. Where this is the case, lay insulation between and overtop the floor joists of these voids. This will retain ground-floor heat, reducing heating bills and wasted energy.
Dormer cheeks (panelling creating the projecting dormer window) are notorious for heat loss. Often these are not properly quality checked at construction stage, and the preponderance of timber in a confined area means that insulation is minimal or even omitted. Again, a little opening up to examine and remediate these is suggested or, where there is room, add an insulated plasterboard. It is recommended to consult a chartered building surveyor before continuing with works. I hope this helps.
Brigid Browne is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland
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