Is Your House Sporting A Beret? It’s That Time Of Year. Keep Looking Up.
It is that time of year. Snow does build up on roofs. You even get snow drifts on roofs with windy conditions.
You also get what I like to call snowbrows. Which may look like your roof is wearing a snow beret.
The right conditions can create built-up overhangs, or ‘brows’ at eves and other roof edges. They often get heavy enough to break of and fall with a big ‘whump’ sound as this pile of snow hits the ground or a lower roof.
Sometimes this happens while it is still snowing. But if the conditions are right they can ‘hang’ there for days, even weeks. They can look ominous but some people think ‘it’s only snow so it’s not a danger’. But that’s not right.
It’s a lot of snow. If it drops on you, you’re going to know it. Remember; a ton of bricks sounds heavy and a ton of feathers (or snow) doesen’t conjure up the same weighty image. But a ton is a ton. You don’t want to be under it.
The second factor here is ice. Did you notice the icicles present? There’s lots of them and they are big. That means something is happening under that snow.
Because snow is cold to the touch, few people think of it as functioning as an insulation, but a thick snow layer is very effective insulation because it is light and airy, it does not allow much heat transfer by conduction. (Igloo and Ice Hotel builders use that to their advantage.)
So when we have deep snow cover on roofs the insulating effect allows heat (loss from the house or solar heat gains from other surfaces) to warm up the roof surfaces. Snow in contact with the roof melts, the water runs down to the cold eve edges and refreezes. This causes the big icicles and ice dams. Those ice dams can back up water till the point that it may run under the shingles and sometimes leak into the interior.
Even if you don’t get interior water, the ice dams build up deeper and thicker and heavier. All or mosly out of sight under the deep snow and snowbrows.
So now if when they fall they will be heavier, harder and pack more punch. Their impact will feel like bricks.
So don’t slam that door!
This front entry door is right under this brow!
Ever when there are no snowbrow buildups, the weight of the snow and ice accumulation can be considerable.
Add rain into that deep snow layer. What do you think happens.? No it does not drain off or melt the snow. The snow soaks it up like a sponge and holds it there. It all stays on the roof.
Was your roof designed for that? Most likely not.
Construction costs usually dictate code minimums designed for average conditions, plus a certain safety factor. The roof should not fail structurally, but it can still be damaged (shingles, sheathing, gutters, water entry, etc.).
It is a good maintenance practice to knock off all over hanging ‘brows’ as soon as they are formed and befor large ice buid-ups can occur.
Big snow accumulations on roof edges are better removed, also early – before ice is allowed to buildup. But this is not cause for panic or drastic action every time you have a big snow fall.
Once you’ve cleared your driveway and walks, have a look at how much is on the roof. The most important areas to clear are the lower half of the sloped roofs.
We recommend using a roof rake (with pole handle extensions) from the ground. Don’t try to remove ice that is too big to break off easily. We do not recommend ice removal. It is to easy to damage roofs, walls and windows this way.
Ice left in place, with no snow cover, will safely freeze to the spot, generally till spring weather gradually reduces them.
If ice mass has to be removed because of damage or water entry problems, have it professionally done. They have the safety equipment, the experience and usually the capability to repair any damaged they may cause.
Avoid slamming the door on winter mornings and remember to “keep looking up”.
Original blog post on ActiveRain: Link to Blog Post