"Andy Hall" wrote in message
...
On Tue, 29 Mar 2005 01:09:55 +0100, "Doctor Evil"
wrote:


"Andy Hall" wrote in message
.. .



Given the age of the house, it presumably has solid walls. WIth the
height involved, unless you lowered the ceilings and insulated
immediately above them to create a cold area above, a considerable
amount of heat will go through the walls.

It's certainly worth insulating the loft because that will be a
considerable heatloss in a mid terraced house, but it is not worth
using more than about 150-200mm of insulating material. The
difference you would make would pale into insignificance compared with
losses through the walls and through draughts.

Two wrongs make a right then.

No, I am simply pointing out that
there is no point in going to
extremes on loft insulation

Lord Hall, 12" is not extreme. In fact, there is no such thing as extreme
in insulation. Put is as much as you can, with 12" being the minimum.

as opposed to a reasonable provisioning
when in comparison large amounts of heat
are going out through the
walls.

It is terraced. At least half the walls is not outside wall.

We had this discussion before

...and you got it wrong then too.

and I gave worked examples with numbers
to illustrate that there was no point in going
above 150mm or so.

With no idea of practical reality.

Yes there was a small amount to
be gained,

There was a lot to be gained in the bedrooms, as the ceiling forms a large
part of the room surfaces. It also works the other way around. The 12" of
loft insulation keeps the heat out of the bedrooms in summer.

In a bungalow the ceiling forms the largest surface area of the house.
Think of the upstairs as a bungalow.

but it was a tiny fraction
of the heat loss through the
walls. Perhaps you have a
short memory or like spending
other people's money.

See above.

It is mid terraced with a small area of
outside wall.

You don't know that the area of outside
wall is small.

It ios not a detached house, that is for certain.

For one thing
the ceilings are very high in comparison
to many properties so loss
through them is greater in proportion.

...in proportion to what?

Most wall area most probably
will be party wall.

It may or may not be.

You have an odd idea of how terraced houses are built.

This doesn't alter the amount going
out through the front and back walls
which is likely to be an order of magnitude
greater than that through the roof even
if you were to only put 100mm
of insulation there.

Because more is going out through the outside wall the roof should neglected
then. What logic.

It is best to
make the ceiling air-tight by using
silicon to block any holes and have an
insulated and sealed trap door, and
12" of Rockwool.

It would be if it were a more modern house.
This property is over 150 years old and
unless one were to implement modern insulation
standards on it comprehensively, there is little
or no value in going mad as you are suggesting
on one aspect.

Mad about what? Insulating the loft to 12" is hardly going mad. The house
will be reasonably air-tight as two sides are not outsides walls. When
replacing windows and doors obviously install sealed units to make the house
more air-tight. The walls will not be cavity, so pretty well air tight
there too. It is air leakages that cost in heating fuel. It is well worth
having sealed doors and windows and ensuring the ceiling is air-tight too.
Then the 12" of insulation will have a great effect.

So, in time new sealed windows would be installed. Having the sealed loft
ceiling and 12" of insulation would compliment that and already be in place.

Irrespective of ceiling
height heat will be lost through
the ceiling at a rapid rate with a thin
layer of Rockwool. Insulating a loft is
easy and cheap.

Nobody was suggesting using a thin layer.
150mm is a very adequate level of insulation
in the context of this property.

It isn't and thin in any property.

If we were talking about a modern
house with cavity walls, cavity
insulation and double glazing, then
there is a marginal case for going
to thicker insulation.

You really don't know do you.

Insulation material is reasonably
cheap but it isn't free. In this
case 300mm is overkill.

Highly cost effective and it will pay for iteself very quickly as oil (fuel)
prices rise in future. They NEVER go cdown.

The case you are making is equivalent
to arguing for a 40W bulb rather
than a 60W bulb when there is a 3kW
fire in the room.

What a mad analogy.



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