Since locating our new central heating boiler into the loft I find I
need to convert from cold loft to warm loft to limit excessive gas
bills in the winter from the frost thermostat being constantly on.

The question is - what would be the best way to achieve this?

The house is a 1950's semi with no sarking under the tiles (tiles
visible from inside loft). Present insulation is 200mm glass fibre on
loft floor.

Most loft insulation manufacturer websites I have visited assume
sarking is present.

Thanks in advance for any advice.




--
Big G

On Tue, 4 Jul 2006 22:07:47 +0100, Big G
wrote:


Since locating our new central heating boiler into the loft I find I
need to convert from cold loft to warm loft to limit excessive gas
bills in the winter from the frost thermostat being constantly on.

The question is - what would be the best way to achieve this?

The house is a 1950's semi with no sarking under the tiles (tiles
visible from inside loft). Present insulation is 200mm glass fibre on
loft floor.

Most loft insulation manufacturer websites I have visited assume
sarking is present.

Thanks in advance for any advice.

How often does your loft freeze in winter? Even if it did occassionaly
freeze the boiler wouldnt be using much gas as its not heating the
house.

I wouldnt bother.

Most loft insulation manufacturer websites I have visited assume
sarking is present.

Lack of sarking makes it easier. Think of it as a VERY breathable membrane.

You can fully fill between the rafters with K7 Kingspan and then lay K18
boards underneath, tightly butted.

http://www.insulation.kingspan.com/newdiv/pdf/k7.pdf

Your will be the first method described in Figure 1a "Unventilated
Insulation Between & Under Rafters).

If you have 75mm rafters, this will give you a u-Value of 0.24. If you have
100mm rafters, this will give you a u-Value of 0.20.

If using this method on an unsarked roof, you should note that you are
effectively using the foil facing as an imperfect retrofit sarking. Take
care at the bottom of the boards to ensure that any water moving down the
surface will go outside, rather than through the bedroom ceiling.

Christian.

Big G wrote:

Since locating our new central heating boiler into the loft I find I
need to convert from cold loft to warm loft to limit excessive gas
bills in the winter from the frost thermostat being constantly on.

The question is - what would be the best way to achieve this?

Build a frame round the boiler and insulate that, sod the rest of the
loft! ;-)



--
Cheers,

John.

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