Roof insulation.

[artie]

I am going to put 3 by 2 laths on top of my old corrugated tin roof, then apply roll inslaution between them and finally cover again with new tin.

I can't seem to find 50 mm insulation locally is there any advantage to compressing 100 mm into the space.?

 

[Myfordman]

Never compress insulation. It will ruin its effectiveness. Use ready insulated roof panels designed for the job.

 

[artie]

I just got off the phone with an insulation company.

The guy told me I would be as well or better off if I left the gap between the two tins empty.

 

[Eric The Viking]

I've got a second roof on the garage/workshop -

tin roof | insulation | tin roof

The new one has some sort of anti-condensation coating too, but that was really unnecessary as it's not the lower one!

It works well.

At a guess, I'd say it won't be a fraction as effective without the insulation. Can you use 2x4 instead, or even rip them to 2x1 (minus the kerf)? You ought to be able to find something that works at 4". Worst case, if the area is small, can you use Kingspan or similar (comes in a choice of sheet thickness).

I say 'small area' because it's expensive. Mine's done with metal 'rafters' and roll insulation between (4" thickness). It's made a big difference to the condensation problem, and it's now usable in the height of summer, too. but as I haven't been able to insulate the concrete walls or the up'n'over, it's not a complete solution.

I think it's worth the effort for comfort, but as Myfordman says, try to find something that will work in the space.

 

[artie]

The guy at the insulation company reckoned There would be condensation between the tins and not enough air circulation to dry it out.

It's 130 m2 so I don't want to spend on Kingspan..

50mm of free space between the tins would mean that the warm and cold air were not meeting "head on " for want of a better word.

 

[Eric The Viking]

I forgot to say: I now also have a roof I can walk on - the old roof is too thin.

As for condensation: If it's not leaking, and the new one doesn't either, where's the condensation going to come from if you seal up the lower roof?

And I meant rip to 1x4 (not 1x2 d'oh!).