Can I use Polythene Vapour Barrier
(http://www.wickes.co.uk/red-plastic-...s/invt/153230/)

instead of building paper before I put down insulation in the loft (only
has 5mm of foam beads at present and no ventilaton)


--
zaax
My weather: http://tinyurl.com/ch6krz

in 1097460 20120115 233618 zaax wrote:
Can I use Polythene Vapour Barrier
(http://www.wickes.co.uk/red-plastic-...s/invt/153230/)

instead of building paper before I put down insulation in the loft (only
has 5mm of foam beads at present and no ventilaton)



zaax
My weather: http://tinyurl.com/ch6krz

Your weather stopped over 2 days ago :-)

On Mon, 16 Jan 2012 07:49:44 GMT, Bob Martin wrote:

in 1097460 20120115 233618 zaax wrote:
Can I use Polythene Vapour Barrier
(http://www.wickes.co.uk/red-plastic-...s/invt/153230/)

instead of building paper before I put down insulation in the loft (only
has 5mm of foam beads at present and no ventilaton)



zaax
My weather: http://tinyurl.com/ch6krz

Your weather stopped over 2 days ago :-)

Site's frozen.
--
Peter.
The gods will stay away
whilst religions hold sway

On Jan 15, 11:36*pm, zaax wrote:
Can I use Polythene Vapour Barrier
(http://www.wickes.co.uk/red-plastic-...s/invt/153230/)

instead of building paper before I put down insulation in the loft (only
has 5mm of foam beads at present and no ventilaton)

--
zaax
My weather:http://tinyurl.com/ch6krz


These two products are at opposite ends of the spectrum.

Building paper is vapour permeable/breathable. In theory, it will let
water vapour through but not liquid water

Vapour barrier is completely impermeable.

In the application under discussion,
Vapour barrier is intended to go on the warm side of your insulation.
Building paper might be used on the cold side. (but probaly not in the
loft)

This is to prevent condensation occuring within the insulation from
warm moist air from inside the house.

And if it does, the permeable barrier lets it escape.

5mm of beads? You may as well throw them away.

On Jan 16, 8:49*am, harry wrote:
On Jan 15, 11:36*pm, zaax wrote:

Can I use Polythene Vapour Barrier
(http://www.wickes.co.uk/red-plastic-...s/invt/153230/)

instead of building paper before I put down insulation in the loft (only
has 5mm of foam beads at present and no ventilaton)

--
zaax
My weather:http://tinyurl.com/ch6krz

These two products are at opposite ends of the spectrum.

Building paper is vapour permeable/breathable. In theory, it will let
water vapour through but not liquid water

Vapour barrier is completely impermeable.

In the application under discussion,
Vapour barrier is intended to go on the warm side of your insulation.
Building paper might be used on the cold side. (but probaly not in the
loft)

This is to prevent condensation occuring within the insulation from
warm moist air from inside the house.

And if it does, the permeable barrier lets it escape.

5mm of beads? *You may as well throw them away.

very roughly equivalent to around 3mm solid insulation, which does
make a useful difference. But nowhere remotely near enough by modern
standards.


NT

On 16/01/2012 08:49, harry wrote:

These two products are at opposite ends of the spectrum.

Not necessarily.

Building paper is vapour permeable/breathable. In theory, it will let
water vapour through but not liquid water

That describes a 'breather paper' but you should know that there are
many grades of building paper (see BS 1521), some of which are intended
for use as vapour barriers.

http://www.bsk-laminating.com/sisalkraft.htm refers.

Vapour barrier is completely impermeable.

Nothing is completely impermeable.

--
Andy

Andy Wade wrote:
On 16/01/2012 08:49, harry wrote:

These two products are at opposite ends of the spectrum.

Not necessarily.

Building paper is vapour permeable/breathable. In theory, it will let
water vapour through but not liquid water

That describes a 'breather paper' but you should know that there are
many grades of building paper (see BS 1521), some of which are intended
for use as vapour barriers.

http://www.bsk-laminating.com/sisalkraft.htm refers.

Vapour barrier is completely impermeable.

Nothing is completely impermeable.

Many things are so impermeable to some substances that you might as well
say that..

Air does not leak into mercury/glass barometters for example.