Snow time like the present (to look at your roof)

We’ve had snow over most of the UK this week, and media and social-media have been saturated with it. So get out in it and take some pretty pictures, and whilst you are at it, take a look at your roof.

Why? To see how much snow is on it! Why? Because it will give you a good guide to how much heat is escaping through your roof, and thus how much money you are wasting.

Given that it’s only just below freezing at the moment, it doesn’t take much to melt snow; you may notice that some of the man-hole covers in your street are snow-free: that’s due to the energy we flush down the drain when we bathe or otherwise use hot-water. A similar thing may be happening on your roof.

A well insulated loft or roof will have a nice coating of snow that will last all day, a poorly insulated roof may have no snow at all and look wet. Here’s some examples from my walk about today:

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The front roof on the centre house is completely snow-free, and very wet looking: in comparison the roofs on either side are nicely coated in snow. There’s either some major tropical heating going on up there (which is incidentally how the police often spot cannabis farms!), or there’s zero insulation in this loft. The ironic thing is that the windows look like decent double-glazing, which is relatively expensive, but nearly as much heat escapes through an uninsulated roof as a single-glazed window, and insulating the loft is much cheaper than new windows!

Another example:

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These houses are basically identical; which has the better loft insulation? No prizes for guessing that the right one is either completely unheated, or has some decent insulation; the left one may have some insulation, but escaping heat is rising to the apex and melting the snow. I’d top it up, if that were my place, and make sure the loft-hatch is sealed and insulated.

Finally, my house 🙂

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Mine’s the roof on the right. No slush here! I’ve got about 400mm (1’6″) of fibreglass insulation, and I also insulated under my loft-storage area with polyurethane boarding so it didn’t have less insulation than the rest of the loft. The loft-hatch is also insulated with a couple of layers of foil-backed bubble-wrap, and sealed with draft-excluder tape.

Next door has a loft-extension, which must have been well done, since it’s also thaw free; I see a lot of loft-extensions in Ealing, and very few of them seem to have been well insulated, judging by the amount of melt!

Apologies for following my winter obsession, but properly insulating your loft is one of the cheapest and best value DIY jobs you can do, and you don’t need anyone to come and do a survey with a fancy infra-red camera to see if you need it, just a little bit of snow.

2 thoughts on “Snow time like the present (to look at your roof)”

  1. Hey There Ellispritchard,
    This might be off topic, however, How does the solar panel PV system works in the Canadian winter during the snows. Will snow melt off by itself from the solar panels or certain angles I have to look into during installation. Do I have to bush off snow if I install it on the roof in the winter time.
    BTW great blogpost

    1. Hi Dakgrind,

      Generally, if the snow is thick and covering the panel(s) then they won’t work at all, and remember that you’ll get much less solar energy in the winter, at our high latitudes (lower-sun, shorter days), so output will be low even with snow-free panels.

      To maximize output, a steeper angle than normal will both help snow to slide off, and maximize winter generation, so in your climate, being able to alter the panel’s angle depending on the season would definitely be an advantage.

      In the UK our snow doesn’t tend to stick around long, is often quite wet, and slides off of panels as soon as it warms up a bit. Despite your more reliable snow, and longer colder periods, you probably get more clear, bright days in Canada than here in the UK, where we tend to get very dull, overcast days for most of the winter, so solar is potentially better in Canada, if you can keep the panels clear.

      I found this article on the subject which covers pretty much all this: http://homeenergypros.lbl.gov/profiles/blogs/what-happens-when-you-get-snow-on-solar-panels

      Ellis.

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