cavity wall insulation exposed to weather

A friend is having an extension built and the cavity wall and
insulation is not yet completed and was open to the elements at the
top.

Due to the weather the builders have stopped work but did not cover
the top of the wall.

My friend was concerned that the insulation would get damp and he was
concerned whether it could cause problems once the wall was completed.

I said I didn't think it would be an issue as you could expect
dampness from the mortar etc and this would dry out over time. But
what do the group think? Should he get the builders to replace the
insulation.( probably easier said than done due to the wall ties.)

 

The builders won't replace the insulation unless the customer wants to pay
for it.
It will dry out within a few days - while it may look waterlogged, it's
actually not - it's treated with a waterproofing chemical, which is why
penetrating damp/moisture doesn't track across it

 

Mine got sopping wet..it dries out eventually.

Through the brickwork.

As long as it doesn't slump..

 

A good builder will cover the top of the wall while it is being built.

Not only to protect from frost, but to prevent the wall becoming
saturated by rain - which will then cause effloresence to the
brickwork as it dries out and brings salts to the face.

Moisture from soaked insulation will dry out through the brickwork -
again increasing chances of effloresence on the surface. In addition
the water repelant qualities of the insulation will be degraded or
removed - which may cause problems later if the external wall ever
gets saturated from a good downpour.

The top row of insulation should be changed, and it should be insisted
that the builder covers the top of the wall in future.

dg

 

That will happen anyway inmost cases..the ortta is wet and rain happens.
it goes away once the salts have all leached out.

I really don;t think its that critical to be honest.

 

The majority of cases of efflorescence are where the bricks were
saturated before laying, or get soaked from above/behind after laying.
I don't recall ever seeing efflorescence go away on its own or by
brushing - it is normally there for a very long time to spoil the
wall, and could have been prevented.

Wet mortar or the face of the wall is not a problem, it's when the
bricks are saturated through - which happens from the top, when it is
a problem.

Covering a simple thing to do and can the difference between a nice
and crap looking wall.

dg

 

Not in my house.

The majority was on exposed bricakwork *vhimey stacks only) and has all
gone.

The stacks were layed in blazing sunlight, and were covered over each
night, more to keep the sun off than the rain.

They effloresced for about a year, and then it wall eventually washed off.

Look up a few sites on efflorescence..its almost standard with new
brickwork and it almost always stops in time.

Well your experience must be either imaginary or extremely limited.

It is almost guaranteed to happen on new brickwork.

Actually that is precisly what causes efflorescence. Wet new brickwork.
From rain chiefly. To get to the outside, the salts have to be soluble.
Being soluble, they wash off eventually.


it's when the

Bollocks. What about garden walls with exposed tops? Or parapet walls.
Brick walls that get soaked - solid ones - are common as muck. You cant
tell me that a single line of laid brick is any different from a cavity
all that is wet inside..

Bricks should be soaked anyway - porous ones - before laying.

Its a simple thing to do, but it makes bugger all differnece to appearance.

You cover fresh blockwork to stop the rain washing the cement out of the
mortar before it sets, to stop they sun drying it out before it sets and
to stop the frost freezing it before it sets. NBy and large those are
mechanical issues, not aesthetic. Of course if you do get cement leaking
out, a stupid person might think it was efflorescence, and note that it
didn't come off of its own accord.

The rest of us use brick acid and a wire brush...