Insulated room losing heat

If you have the option of obtaining an IR thermometer try use it on a cold day when the room is well warmed up. You might find that the top of the wall just under the ceiling is a bigger loss (by surface-area) than the reveals. While the reveals can cause loss, they can be relined with insulated plasterboard, but it's not such an easy job if the loss is from the cavity closer at the top of the wall.

Good thread here:

What i got started years ago when rooms were getting done my brickwork on the inside got insulation boards fitted + the ceiling as old houses had paper boards with easy to put a hole in it. Windows are double glazed also. Rad beside bed not switched on.

I like a cool room to sleep in and even at -10c outside i am cosy inside. Drafts will cool rooms down quickly , check any vents are not cooling rooms down , attic trapdoor sealed? open chimneys?

I bought a cheap(ish) Black and Decker IR thermometer (that is marketed as a Thermal Leak Detector). You point it at the wall when you turn it on. It measures this point and this is the 'set point', and you get a green dot on the wall. You then move it around the wall and colder spots give a blue dot and hotter spots change to a red dot. It allows you scan a wall, window etc. and you can quickly highlight area where there is a temperature difference and hence areas where there is more heat loss than another. It's obviously not as good as a FLIR camera, but is a fraction of the cost.

My 50 year old house has non bonded beaded insulation in the cavity. I can see using this device that the insulation has 'sagged' and only extends to about the top of the window. When I move this device up the wall the dot changes from green to blue about level with the top of the window.

IR thermometerin Lidl at the moment for 17.99.

For that price worth a shot.

I have this and it's really useful.

Other than the obvious point about the area under the water tank, check for draughts coming in under the skirting or anywhere else there's a gap. Our kitchen is the only properly insulated room in the house but whenever the wind is coming from the east it's freezing, and it's because there are draughts coming in. Using the IR thermometer I've been able to find that the area behind the skirting is one of the problem areas but haven't tracked down where the air is actually getting in yet. The IR thermometer also allowed me to check that the walls, ceilings etc weren't cold so it's not missing insulation that's the problem.

Sounds like the floor IS a problem. Is this correct ??

In the house im in now, The walls are consrtructed of 9" thick cavity (hollow) block. The Joists for the upstairs floors are simply mounted on the top of the block, some cut off (read 'Hacked') solids are placed between the joists on the inside edge and outside edge of the cavity block, then the next course of cavity blocks are placed on top of this.

This forms a continous cavity from foundation to roof. The topmost blocks are not capped, so any air that gets into the cavity flows straight out the top. Heat rising of course sets up a draught as good as any chimney.

Now the problem is where the joists penetrate into the wall, the hacked off block leaves a gap. If there's 25 joists, and each joist has a 10mm gap each side of it, thats (25x 2 x 225 x 10)mm Thats a 0.11 square meter hole from the inside of your house to what is effectively the outside. Doesnt sound like a lot, but its 1/2 meter long by 1/4 high, or might sound more accurate if you say 200 Sq inches.

So the 60mm insulation should be extended under the upstairs floor to seal to the plasterboard ceiling below, and sealed to each joist.