Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch help
to melt the snown and keep the weight / depth down?

--
---
zaax
Frustration casues accidents: allow faster traffic to overtake.

zaax wrote:
Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch
help to melt the snown and keep the weight / depth down?

It could add to the roof's burdon! The heat could cause snow to melt and
compact without leaving the roof allowing more to be added! If you wish to
use a lot of fuel then turn the heating up, remove the hatch add make sure
it melts quickly.

Overall, my take is that it would not be of benefit.

zaax wrote:
Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch help
to melt the snown and keep the weight / depth down?

In 1963, the roof on our house survived, but the gutters were brought
down when the snow started to melt and slide over them.

Colin Bignell

Nightjar "cpb"@ insertmysurnamehere wrote:
zaax wrote:
Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch help
to melt the snown and keep the weight / depth down?

In 1963, the roof on our house survived, but the gutters were brought
down when the snow started to melt and slide over them.

Colin Bignell
a typical TILED or SLATED rod is massively heavier than any snow its
likely to collect this side of Novosibirsk.

The same cannot be said of shed felted rooves...

On Sat, 09 Jan 2010 01:16:32 GMT, "zaax"
wrote:

Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch help
to melt the snown and keep the weight / depth down?

On this morning's Farming Today This Week (6:30 am) a farmer
interviewed said several barn roofs had collapsed due to the weight of
snow, crushing and killing some sheep in one instance.

MM

On Sat, 09 Jan 2010 10:14:53 +0000, MM wrote:

On Sat, 09 Jan 2010 01:16:32 GMT, "zaax"
wrote:

Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch help
to melt the snown and keep the weight / depth down?

On this morning's Farming Today This Week (6:30 am) a farmer interviewed
said several barn roofs had collapsed due to the weight of snow,
crushing and killing some sheep in one instance.

When we bought this house, the surveyor had some comments about the roof.

Originally slate, it had been tiled, tiles being a lot heavier. He said
it was fine, but could have problems with much extra weight (e.g. snow).
He suggested some extra support, which was cheap and easy to fit. Glad we
did!




--
Use the BIG mirror service in the UK:
http://www.mirrorservice.org

On Sat, 09 Jan 2010 09:30:42 +0000, Nightjar "cpb"@ wrote:
zaax wrote:
Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch help
to melt the snown and keep the weight / depth down?

In 1963, the roof on our house survived, but the gutters were brought
down when the snow started to melt and slide over them.

I've got some scarey large icicles forming from my gutter (which is frozen
and full of ice). Some are hanging over the front door - so it has to be
closed gently to prevent the risk of getting skewered :-)

In article ,
"Nightjar \"cpb\"@" "insertmysurnamehere writes:
zaax wrote:
Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch help
to melt the snown and keep the weight / depth down?

In 1963, the roof on our house survived, but the gutters were brought
down when the snow started to melt and slide over them.

Looks like that's happening to neighbour's (new) roof.
Also saw some in the high street where gutters are
twisted right round, but snow has now gone (presumably
no loft insulation). These are all slates - doesn't seem
to be slipping down tiled roofs so much.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

[Default] On Sat, 09 Jan 2010 01:16:32 GMT, a certain chimpanzee,
"zaax" , randomly hit the keyboard and
wrote:

Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch help
to melt the snown and keep the weight / depth down?

The rafters and other members are designed to support a load of
0.6-0.75kN/m^2 (& 1.0kN/m^2 for roofs in the North of England over
100m above sea level). My maths and a trawl through Wikipedia suggests
that this is about 750mm of powdery snow. If it were to 'settle' on
the roof, that could be about 200mm of snow.

Within the design code there is a factor of safety of about 1.6 for
imposed loads. Also, the main limit on timber sizing tends to be
deflection, which will usually manifest itself before bending forces
are exceeded. In addition, there are further safety factors included
in the strength classes of the timber and the calculations.

A modern trussed roof is generally designed to the limit with no
additional factors of safety, other than those required by the codes.
A modern roof to a more traditional design, whilst more reliant on
individual members (purlins, hips, etc), is more likely to be
'over-designed'.

In other words, don't worry.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have I strayed"?

[Default] On 9 Jan 2010 10:57:30 GMT, a certain chimpanzee, Bob Eager
, randomly hit the keyboard and wrote:

When we bought this house, the surveyor had some comments about the roof.

Originally slate, it had been tiled, tiles being a lot heavier. He said
it was fine, but could have problems with much extra weight (e.g. snow).
He suggested some extra support, which was cheap and easy to fit. Glad we
did!

I sold a house like that. I managed to prove that, with extreme snow
load, the bending forces on the purlins wouldn't be exceeded, but that
there might be about 50mm deflection in them. As there were no brittle
finishes attached to them, that wouldn't matter.
--
Hugo Nebula
"If no-one on the internet wants a piece of this,
just how far from the pack have I strayed"?

"dave" wrote in message
...
On Sun, 10 Jan 2010 15:58:37 +0000, Hugo Nebula abuse@localhost
wrote:

[Default] On 9 Jan 2010 10:57:30 GMT, a certain chimpanzee, Bob Eager
, randomly hit the keyboard and wrote:

When we bought this house, the surveyor had some comments about the roof.

Originally slate, it had been tiled, tiles being a lot heavier. He said
it was fine, but could have problems with much extra weight (e.g. snow).
He suggested some extra support, which was cheap and easy to fit. Glad we
did!

I sold a house like that. I managed to prove that, with extreme snow
load, the bending forces on the purlins wouldn't be exceeded, but that
there might be about 50mm deflection in them. As there were no brittle
finishes attached to them, that wouldn't matter.

Ask David Cameron - he's always on about fixing roofs while the Sun
shines :-)
Sorry, political, will get my...

That bunch of Hurray Henry Old schoolboys (mainly from Eton) are out to line
their own pockets. Not changed since the wicked witch was in power:

Extract from Ricardo's Law: House Prices and the Great Tax Clawback Scam by
economist Fred Harrison ..........

In the 1980s Hesseltine led the Thatcher government's attempt to deal with
the aftermath of the Toxteth riots. Hesseltine decide that inner-cities
should be rehabilitated. Within a mile of Liverpool's city centre and
Toxteth were 1,000 acres of of abandoned industrial wasteland. In London
6,000 of abandoned acres were in Docklands.

His twofold solution:

1.. Invest taxpayers' money in infrastructure to attract private
enterprise. This delivered windfall gains to owners of adjoining land and
raised the cost of rented accommodation to low income families.
2.. Exempt real estate from property tax. This attracted warehouse type
of investment with low labour content to areas of high unemployment - of
little help to the marginalised dwellers of the decaying hearts of Liverpool
and London.
Hesseltine did not understand that private landowners were as responsible
for the dereliction which he observed as was 'the large-scale hoarding of
land in the public sector'. When he was escorted back to Liverpool in 2006
by Cameron, it appeared that a future Tory government would repeat the
mistakes of the Thatcher years. Hesseltine commended investment in
capital-intense infrastructure that would make their assets highly valuable.
...
...
The Thatcher government decided in 1980 that London's Docklands should be
redeveloped. Its primary tool stood justice on its head. Instead of imposing
public charge on vacant land - to force it into new uses [this also stops
land speculating] - the government created an enterprise zone. One of the
privileges was exemption from property taxation.

The result was predictable. Tax relief was capitalised into higher land
values, and families which for generations had made Docklands their homes
were pressurised out of the area. Those who did not own land were the
losers. The windfall gains did enrich some people. Arnold Fulton purchased a
plot of land in a derelict corner of Docklands for £650,000. Developers
pursued him fending off their offers until he took £30 million.

Hugo Nebula wrote:

[Default] On Sat, 09 Jan 2010 01:16:32 GMT, a certain chimpanzee,
"zaax" , randomly hit the keyboard and
wrote:

Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch
help to melt the snown and keep the weight / depth down?

The rafters and other members are designed to support a load of
0.6-0.75kN/m^2 (& 1.0kN/m^2 for roofs in the North of England over
100m above sea level). My maths and a trawl through Wikipedia suggests
that this is about 750mm of powdery snow. If it were to 'settle' on
the roof, that could be about 200mm of snow.

Within the design code there is a factor of safety of about 1.6 for
imposed loads. Also, the main limit on timber sizing tends to be
deflection, which will usually manifest itself before bending forces
are exceeded. In addition, there are further safety factors included
in the strength classes of the timber and the calculations.

A modern trussed roof is generally designed to the limit with no
additional factors of safety, other than those required by the codes.
A modern roof to a more traditional design, whilst more reliant on
individual members (purlins, hips, etc), is more likely to be
'over-designed'.

In other words, don't worry.

thanks for that, I was when I saw a foot of snow on the roof opposite

--
---
zaax
Frustration casues accidents: allow faster traffic to overtake.

On 12 Jan, 00:12, "zaax" wrote:
Hugo Nebula wrote:
[Default] On Sat, 09 Jan 2010 01:16:32 GMT, a certain chimpanzee,
"zaax" , randomly hit the keyboard and
wrote:

Theres seems to be about a foot of snow on local roofs

How much snow can a modern roof take? Would opening the loft hatch
help to melt the snown and keep the weight / depth down?

The rafters and other members are designed to support a load of
0.6-0.75kN/m^2 (& 1.0kN/m^2 for roofs in the North of England over
100m above sea level). My maths and a trawl through Wikipedia suggests
that this is about 750mm of powdery snow. If it were to 'settle' on
the roof, that could be about 200mm of snow.

Within the design code there is a factor of safety of about 1.6 for
imposed loads. Also, the main limit on timber sizing tends to be
deflection, which will usually manifest itself before bending forces
are exceeded. In addition, there are further safety factors included
in the strength classes of the timber and the calculations.

A modern trussed roof is generally designed to the limit with no
additional factors of safety, other than those required by the codes.
A modern roof to a more traditional design, whilst more reliant on
individual members (purlins, hips, etc), is more likely to be
'over-designed'.

In other words, don't worry.

thanks for that, I was when I saw a foot of snow on the roof opposite

--
---
zaax
Frustration casues accidents: allow faster traffic to overtake.

My under-timbered, shallow pitched, corrugated light plastic lean-to
roof at the side of the garage gave me a warning yesterday evening
when it started to drip through.

One of the roof panels was a recycled one and had the odd nail hole in
the top of the corrugation, which is obviously not a problem with
rain, but is one with melting snow. So at 7pm yesterday evening I was
togged in full waterproof gear and shovelling the snow I could reach
off this roof from a ladder. The dripping at least stopped.

One of this summer's jobs will be to replace this roof - bearing in
mind the weight of wet snow, not that this is likely to be a problem
now for another 30 years!

Rob