300mm Insulation Installed but appears ineffective.

[RobinFDIY]

Hi All,

I'm looking for a bit of on advice. My house (1920's bungalow) is notoriously cold and had condensation issues. I've replace the floors due to wood worm(suspended floor, strip foundation) and insulated with rock wool as I went - this doesn't seem to have made a huge difference to getting the house warm.

My next port of call was to improve the insulation in the loft as the neighbours house attached to mine, who recently had spray insulation installed, would have a frosty roof much longer than mine on cold mornings. (see attached picture).

However when I went to measure how much insulation I needed I discovered that there was already 300mm of fresh insulation installed (I've only been in a year so always finding surprises). I did discover that the attic is unvented and identified signs of condensation wood but will that render the insulation ineffective? The insulation did appear dry and not damp. I will be getting vents installed.

At present, we've had a cold spell (sub zero) for over a week and its been very difficult to heat the house above 18C. Worse is heat seems to leave rooms very quickly and having redone them, they aren't overly drafty.

The loft has been partially converted, and insulated between the plasterboard and the roof. You can see on the picture that the top half of the roof is still frost and the melt line start half way down. Its typical for top half to still be frosty and the whole bottom of the roof to be melted.

Can anyone shed some light on this?

 

[Notch7]

I would start by checking for air leaks into the loft - is the loft hatch sealed and ventilated?

Do you have an airing cupboard that might be pumping heat into the roof

you might have gaps in insulation at eves - it’s tricky as you don’t want to stuff insulation into the eves as it might block ventilation, yet at same time leaving gaps for heat to get through from ceiling below

you could add another 150 mm of insulation -and is current insulation done correctly, it needs to be not squashed down.


Is your central heating in good shape - maybe it’s suffering sludge build up or TRV are partly seized and rads are not heating fast or evenly. Is the system balanced?

 

[Loofah]

What wall construction is it? My bungalow of similar age has single skin so we've lined the walls (50mm celotex I think) and it makes a huge difference

 

[freddiemercurystwin]

Do not ever get tempted by spray foam insulation.

 

[JohnD]

At present, we've had a cold spell (sub zero) for over a week and its been very difficult to heat the house above 18C. Worse is heat seems to leave rooms very quickly and having redone them, they aren't overly drafty.

How much gas (or electricity) did your heating use per day in the cold spell?

 

[JohnD]

As for the roof, the position of the hot patch suggests a source at the party wall, perhaps a loft lamp or a gap in the insulation or a hot pipe or heat escaping from the neighbour.