Snow is here.. time to spot those houses with poor roof insulation

post your photos here

1 to 20 of 69 messages
Dark Vader    pirate
05/12/2012 at 10:10

This is a pet subject of mine...  here are some I spotted this morning..



Dark Vader    pirate
05/12/2012 at 10:11


Dark Vader    pirate
05/12/2012 at 10:13



05/12/2012 at 11:25

I think maybe you have too much time on your hands!

05/12/2012 at 11:42

I find those pictures strangely compelling... 

Dark Vader    pirate
05/12/2012 at 11:44

I'm a building surveyor...  I see houses every day and this issue of melting snow on roofs is always a good one to illustrate to people that money is literally being wasted through the roof.

Its very disappointing to see so many houses with roof conversions that have this problem.  Solid insulation boards used in conversions are really good products but so so often the workmanship in their installation is poor.  I see this over and over and also generally with modern houses.  Its such an easy bit of DIY to tackle, and not even very expensive.  Some energy companies give the stuff away for free!


Edited: 05/12/2012 at 11:46
Iron Pingu    pirate
05/12/2012 at 11:45

Wilkie, that's exactly what I thought, lol, still, an interesting thread.

05/12/2012 at 11:58

I did notice the houses with poor insulation from the train this morning, but I didn't take any photos.

cougie    pirate
05/12/2012 at 12:49

Our local council was doing free loft and cavity wall insulation last year so it seemed silly not to take them up on the offer.  Sadly no snow so I cant see if its working...

05/12/2012 at 12:51

As you said, on the whole it seems to be those with loft conversions that have the problem.

05/12/2012 at 13:04

As a building surveyor can I ask you about my house. Upstairs in winter all windows in the morning are covered with condensation so much you can't look out, there are puddles on the windowsill. They are all double glazed. I have heating low (18C) but then don't feel I need more. Not any other houses around have this problem. There is the same in the hallway and in the bathroom, downstairs is condensed at the bottom of the windows only but then we are mainly downstairs in winter. Also the frames of the windows upstairs have mould on, the surfaces that touch each other when closing or opening and the wall next to the window get mould on and I have to remove it every week or so. I can't get my head around it, is the heating too low or the windows are to blame. The window pane is so cold in winter. I remove all water daily, open windows and wipe up all condensation but by the time I go to bed it's back to being the same and I have to start over in the morning. Any ideas?

Dark Vader    pirate
05/12/2012 at 13:23

We get lots of enquiries about condensation issus every winter.  Its a common problem and can be made worse by the lifestyle of the occupier.

In simple science terms, condensation occurs when there is an imbalance between humidity, thermal insulation, ventilation and temperature.   As temperatures drop, the humidity will seek to condensate on cold surfaces.   Window are obviously vulnerable areas.  This is especially prone where ventilation is poor.  A common observation will be in your bathroom after you have had a shower.  The mirror and window may be steamed up.

Modern double-glazed windows, especially cheap ones, can be to blame too.  Older plastic framed double-glazing had frames that weren't insulated.  This means that as well as heat loss through the glass, you get heat loss through the frame itself.

Interestingly, you can get condensation on the OUTSIDE of the window if you have Pilkington K glass double-glazed windows and a north facing elevation.

Condensation will alos occur in roof spaces that have thermal insulation but poor natural ventilation.

A short-term fix is to use a de-humidifier.   Longer-term though you have to pay attention to natural ventilation, especially in poor heated (or low temperature) environments.  Another example is those with electric storage heaters and peple who dry damp washing internally.

So..  you need to raise the air temperature ensure natural ventilation occurs and particularly that you use externally vented extract fans in the bathroom and kitchen during and after use.  Thermal insulation will slow down heat loss and will encourage a warmer internal wall surface temperature.

Some types of construction (concrete for example) are just prone to it but in almost all cases it is fixable by amending your lifestyle and remembering to ventilate the house and keeping it warm.

In your case, the windows may well be to blame, but also you need to consider these other aspects I mentioned.


Dark Vader    pirate
05/12/2012 at 13:29


This is condensation within a roof.   That is actual water drops you can see on the roofing felt.  This roof is insulated but has no ventilation.  Installing ventilating roof tiles on the back and front slopes will fix this.


Dark Vader    pirate
05/12/2012 at 13:33


This is quite severe condensation on old 1970's Everest double-glazed windows...  this is entirely due to the lifestyle of the occupier.

05/12/2012 at 13:37

I have an extractor in the bathroom (but no window), but water condenses inside the pipe which goes up (and out), and drips back down (fortunately straight into the toilet).

This has also caused three extractor fan motors to blow over the years, as they get wet from the condensation getting in them.


Dark Vader    pirate
05/12/2012 at 13:38



This is very severe.  This is a bathroom with severe condensation.  The fan doesn't work.  Look closely though and you'll see a fungus on the wall.  It is called peziza and it occurs because the wall is saturated.   One of the risks is dealing with this is that as the structure dries out, the moisture content lowers to the range where dry rot can occur.  At the moment it is too wet.  Therefore, you can solve one problem and create another.   Fixing this needs to be handled very carefully.


05/12/2012 at 13:51

Mine's nothing like that, thankfully!  Just the dripping into the toilet.

05/12/2012 at 14:21

I don't have that issue.... the heating would have to be on for it to happen

seren nos    pirate
05/12/2012 at 14:26

the ones with snow on the roof could just have no heating on..........


Our loft conversion was done to planning permission and building regs....couldn't believe the amount of wood.insulating boards.chicken wire etc went to make it...........

the majority just seem to have a few boards put up

05/12/2012 at 14:36

Wilkie - I had a similar issue with a dripping extractor fan. Have you checked the hose that goes between the fan and the outside world? Mine had a loop in it, so the extracted air condensed and settled in the hose until it built up to a level where it started dripping.

In my case, I lifted the hose and about a pint of water poured back into the bathroom

I've since shortened the hose so that the air has a much shorter journey to the outside. Also, I leave the fan running for for a bit longer to dry any condensation.

Any use? 

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