"brugnospamsia" wrote in message
. uk...
Dear group,

It is my intention to replace my upstairs floors with chipboard,
enabling
me
to re-use the boards downstairs for a sanded floor. As I will be
improving
the ventilation under the ground floor, I hope to staple netting
between
the
joists and insulate with 50mm of mineral wool.

I Googled for info on sealing draughts in non-tongue_and_groove and
mostly
found the usual papier mache and solid wood fillets solutions.

I'm wondering if breathable roofing membrane directly under the boards
might
be a better solution
(or maybe used in place of netting to suspend the mineral wool ?)

I've used the foil covered Airtec stuff Screwfix sell as it forms a
condensation barrier as well. Also I used Kingspan instead of mineral
wool
(second quality is fine in this application) rammed between the
floorboards
as it insulates better.


Sorry to be dense, but is this what you mean ?

http://uk.geocities.com/gentlegreengiant/floor.JPG


Not quite. I thought you said you had the floor up and so I would run the
Airtec over the top of the Kingspan and over the top of the joists so that
before you lay the floor all you can see is Airtec.

If the floor has been fitted then you could instead run the Airtec under the
bottom of the joists as well as under or on top of the Kingspan. The
problem with this method is moisture could be retained against the joists so
you need to build in some slack so that any condensation drains away from
the joists, not towards them.

Either way gives you want one continuous run across all the joists, then
taped up in parallel to give a complete impervious sheet.