Help! Snow melting on newly insulated roof

[Airframe]

Hi all,

I dont know what to do. We had 8 inches of snow 2 days ago. The roof of my 1930's semi is the only house in the street where the snow has totally melted from the roof. We had a new roof (clay rosemary tile) 6 month ago. We had a professional company in 2 month ago to insulate the loft. The insulation looked good to me, in line with regulations for thickness and an assessor from the company came to check the quality of the job. Not only has most of the snow melted there appears to be considerable damage to the aluminium seamless gutter.

So I am left wondering why this has happened. See photo's (my house is the one on the right).

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• Airframe
• 19 Dec 2010
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• Airframe
• 19 Dec 2010
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Can anyone offer any advice?

Thanks in anticipation

 

[htgeng]

So I am left wondering why this has happened. See photo's (my house is the one on the right).

Can anyone offer any advice?

Pictures showing inside the loft?

 

[Airframe]

Leave it with me, on my way up now

 

[freddiemercurystwin]

Maybe your sparkling new tiles have none of the corrosion or gunk that begins to coat roof tiles after time and as such the snow is just slipping off as it cant grip?

 

[anchorbay]

yeah could be that the finish on your tiles is slippery enough for the snow to just slide of as shown on the rear of your house
rosemary tiles have a resin coating ,if you try using a diamond blade grinder on em you find the blade will only cut a few tiles and then its clogged with resin gunk around the blade

 

[Airframe]

Some photo's inside the loft...and it's not that cold up there!

The insulation was put down in October by one of the regions bigger insulation companies. I raised the joists in the boarded area (3mx3m) to give 200mm prior to insulation being layed. The height of insulation hardly compromised under boards, I made sure of it. The loft is approx 80sq metres.

The uninsulated loft hatch is an obvious leak point but surely not to this extent.

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• 19 Dec 2010
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[alittlerespect]

Hi

Have to ask - whats under the chipboard in the centre of the loft space, whatever it is that area of the loft is going to be losing significantly more heat from the rooms below than the rest of the loft space.

This slight detail may have caused the roof tiles to warm up sufficiently to take the outside temperature of the tiles above freezing point causing the ice covering the surface of the tiles to melt and create a slip plane which has allowed the snow to basically slide off the roof, which is indicated in the photo's that you have provided.

Regards

 

[Airframe]

Hi

Have to ask - whats under the chipboard in the centre of the loft space, whatever it is that area of the loft is going to be losing significantly more heat from the rooms below than the rest of the loft space.

This slight detail may have caused the roof tiles to warm up sufficiently to take the outside temperature of the tiles above freezing point causing the ice covering the surface of the tiles to melt and create a slip plane which has allowed the snow to basically slide off the roof, which is indicated in the photo's that you have provided.

Regards

Hi,

Aprox 200mm of insulation. I raised the joists. I also did not compress the insulation, just removed the top 50mm.

 

[htgeng]

First, what does the loft hatch look like? They usually staple rockwool in a bin bag to the back of it. If thats what they've done then you can remove the rockwool. Buy a sheet of 50mm celotex and saw it in four pieces and stack/glue to the back of the hatch.

Also another area which is harder to photograph is the area close to the eaves. If you can carefully crawl to near the edge of the roof and peel back the the top layers of insulation, the insulate between the joists should go right to the very top edge of the wall. If if doesn't, heat from downstairs can leak up and heat the roof that way. My money would be on that cause.... but photos would prove it.

 

[Airframe]

First, what does the loft hatch look like? They usually staple rockwool in a bin bag to the back of it. If thats what they've done then you can remove the rockwool. Buy a sheet of 50mm celotex and saw it in four pieces and stack/glue to the back of the hatch.

Also another area which is harder to photograph is the area close to the eaves. If you can carefully crawl to near the edge of the roof and peel back the the top layers of insulation, the insulate between the joists should go right to the very top edge of the wall. If if doesn't, heat from downstairs can leak up and heat the roof that way. My money would be on that cause.... but photos would prove it.

Hi, the loft hatch has no insulation, could that alone be responsible?

I will get up tomorrow for a photo near the eaves. When you refer to the wool reaching the very top edge of the wall, do you mean bridging the cavity to the outer brick skin. I read the following on the energy trust website and made me wonder if the problem is lack of ventilation.

When you add insulation to attic rafters and attic floors, it’s important to maintain at least a 1-in. continuous air space between insulation and roof sheathing, from eaves to ridge. This air space flushes out moisture. It also helps maintain a “cold roof,” which prevents ice dams from forming in the winter.

And this picture of an 'Ice Dam' is identical to what I see at the back of the house (photo 2)........

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• Airframe
• 20 Dec 2010
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[Nige F]

Maybe your sparkling new tiles have none of the corrosion or gunk that begins to coat roof tiles after time and as such the snow is just slipping off as it cant grip?

Right with you on that Freddy Just looked @ hundreds of rosemarys - salvage from local asylum - clean as when they were laid in 1900 No good as a repair for my skanky discoloured coverwells - shame because they were selling cheap. So those Victorian builders deliberately chose a tile that wouldn`t discolour/grow moss

 

[smashngrab]

Same here,all the old clay double roman tiles are holding the snow ,where as the the new concrete are clearing quicker.