Roof pitch insulation

Since locating our new central heating boiler into the loft I find

need to convert from cold loft to warm loft to limit excessive ga 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 (tile visible from inside loft). Present insulation is 200mm glass fibre o loft floor.

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

Thanks in advance for any advice

-- Big G

Reply to
Big G
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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.

Reply to
marvelus

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.

formatting link
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.

Reply to
Christian McArdle

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

Reply to
John Rumm

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