Loft conversion - low pitch roof

[mayurw]

Hi guys

So I have made an PD application for a loft conversion to my local council recently. Talking to my architect, the one issue I’m going to be faced with is the height. So I’ve agreed to drop the ceilings on the 1st floor down 200mm but with even doing that, I’m still looking at only getting a max of 1.9m headroom in the loft. The architect is going to try and play with the figures but he mentioned that I will be having a cold deck flat roof and we’ll need to use 150x50mm rafters for the span. Now to achieve the 0.18W/m2K required, he said we’ll need to use 100m insulation between the rafters – he said something about leaving a 50mm air gap plus a further 50mm on the underside. I know 50mm doesn’t sound a lot but would there be something on the market that would allow me not to have that additional insulation?


Any advice would be grateful


Thanks

 

[freddiemercurystwin]

No. But you may be able to reduce it to say 20mm by adding additional insulation elsewhere eg in the dormer walls. But your BCO may expect calculations to prove one solution will match the other overall which coud be cost some cash, prolly £100 or thereabouts. Sounds like your lofty is not really viable. Lets hope your designers survey was absolutely spot on, 50mm out and you'll be banging your head!

 

[^woody^]

Get a different architect from the market. One that knows what he is doing and does not need to play about with figures.

He might just play a different game to the builder, and your loft will be like one from the Shires.

 

[Ian H]

How high are your 1st floor ceilings? And are you terraced/semi?

 

[tony1851]

Get a private inspector in instead of the council; the one we use lets us put just 100 between the rafters - and that's it.

 

[noseall]

Another reason why private inspectors are gash.

 

[tony1851]

Another reason why private inspectors are gash.

Not if it makes the loft more useable, and the OP is prepared to forgoe just a little insulation.
It's all down to reasonableness.
On the other hand, if saving the planet is more important to the OP than him having an extra bedroom..............?

 

[mayurw]

How high are your 1st floor ceilings? And are you terraced/semi?

we've got around 2.4m