Spike <aero.spike@mail.com> wrote:
> Theo <theom+news@chiark.greenend.org.uk> wrote:
> > Spike <aero.spike@mail.com> wrote:
> >> There are a number of firms that specialise in cavity-wall insulation
> >> removal, which isn’t a cheap exercise, and there’s also the Cavity
> >> Insulation Victims Alliance who try to get some form of justice for
> >> sufferers of mis-sold CWI.
> >>
> >> CWI is not a universally-acceptable procedure.
> >
> > Agreed it's not an panacaea, but I'd have thought a 1970s brick+block
> > construction would be relatively uncomplicated? It's not into lime mortar
> > and breatheable paints territory.
>
> I did see a map somewhere that showed that large parts of the UK were
> unsuitable for CWI due to the threat posed by heavy driving rain. IIRC the
> whole of Wales and the South West were one such area.

I'd have thought that could be addressed by sealing the bricks from the
outside, so there's no water penetration by the rain. A lot of properties
in eg Wales and Scotland are painted or rendered which takes care of the
sealing.

This is Ireland, which is known for being moist:
https://www.nsai.ie/images/uploads/certification-agrement/IAB050222.pdf

"3.5.2.1.2 Severe Exposure
Severe exposure to wind-driven rain applies in
districts where the driving rain index is
5m²/sec/year or greater (see Figure 2).
In severe exposure areas the type of outer leaf
masonry finish where the Rockwool Blown Cavity
Wall Insulation System is suitable is:
* Impervious cladding and rendered walls with a
minimum cavity width of 50 mm and up to
12m in height.
* Walls must be in a good state of repair with
no evidence of frost damage and no evidence
of damage which would cause water ingress.
Unrendered brickwork is not suitable for full-fill
cavity wall insulation in the severe exposure
zones"

(in other words, sounds like the usual story of cowboy installers and then
ambulance-chasing removals firms)

Theo

Theo <theom+news@chiark.greenend.org.uk> wrote:
> Spike <aero.spike@mail.com> wrote:
>> Theo <theom+news@chiark.greenend.org.uk> wrote:
>>> Spike <aero.spike@mail.com> wrote:
>>>> There are a number of firms that specialise in cavity-wall insulation
>>>> removal, which isn’t a cheap exercise, and there’s also the Cavity
>>>> Insulation Victims Alliance who try to get some form of justice for
>>>> sufferers of mis-sold CWI.
>>>>
>>>> CWI is not a universally-acceptable procedure.
>>>
>>> Agreed it's not an panacaea, but I'd have thought a 1970s brick+block
>>> construction would be relatively uncomplicated? It's not into lime mortar
>>> and breatheable paints territory.
>>
>> I did see a map somewhere that showed that large parts of the UK were
>> unsuitable for CWI due to the threat posed by heavy driving rain. IIRC the
>> whole of Wales and the South West were one such area.
>
> I'd have thought that could be addressed by sealing the bricks from the
> outside, so there's no water penetration by the rain. A lot of properties
> in eg Wales and Scotland are painted or rendered which takes care of the
> sealing.
>
> This is Ireland, which is known for being moist:
> https://www.nsai.ie/images/uploads/certification-agrement/IAB050222.pdf
>
> "3.5.2.1.2 Severe Exposure
> Severe exposure to wind-driven rain applies in
> districts where the driving rain index is
> 5m²/sec/year or greater (see Figure 2).
> In severe exposure areas the type of outer leaf
> masonry finish where the Rockwool Blown Cavity
> Wall Insulation System is suitable is:
> * Impervious cladding and rendered walls with a
> minimum cavity width of 50 mm and up to
> 12m in height.
> * Walls must be in a good state of repair with
> no evidence of frost damage and no evidence
> of damage which would cause water ingress.
> Unrendered brickwork is not suitable for full-fill
> cavity wall insulation in the severe exposure
> zones"
>
> (in other words, sounds like the usual story of cowboy installers and then
> ambulance-chasing removals firms)

Ah…the map I mentioned can be found here:

<https://www.labc.co.uk/news/full-fill-masonry-cavity-walls-and-exposure-wind-driven-rain>

--
Spike

Spike <aero.spike@mail.com> wrote:
> Theo <theom+news@chiark.greenend.org.uk> wrote:
> > I'd have thought that could be addressed by sealing the bricks from the
> > outside, so there's no water penetration by the rain. A lot of properties
> > in eg Wales and Scotland are painted or rendered which takes care of the
> > sealing.
> >
> > This is Ireland, which is known for being moist:
> > https://www.nsai.ie/images/uploads/certification-agrement/IAB050222.pdf
> >
> > "3.5.2.1.2 Severe Exposure
> > Severe exposure to wind-driven rain applies in
> > districts where the driving rain index is
> > 5m²/sec/year or greater (see Figure 2).
> > In severe exposure areas the type of outer leaf
> > masonry finish where the Rockwool Blown Cavity
> > Wall Insulation System is suitable is:
> > * Impervious cladding and rendered walls with a
> > minimum cavity width of 50 mm and up to
> > 12m in height.
> > * Walls must be in a good state of repair with
> > no evidence of frost damage and no evidence
> > of damage which would cause water ingress.
> > Unrendered brickwork is not suitable for full-fill
> > cavity wall insulation in the severe exposure
> > zones"
> >
> > (in other words, sounds like the usual story of cowboy installers and then
> > ambulance-chasing removals firms)
>
> Ah…the map I mentioned can be found here:
>
> <https://www.labc.co.uk/news/full-fill-masonry-cavity-walls-and-exposure-wind-driven-rain>

Yep, that page is talking about new builds rather than retrofits (hence
cavity sizes are something you can control at design time), but it does make
the point that rendering or cladding can allow you to have a full cavity
because there's now an impervious layer to stop the bricks getting wet, and
so the drying function of the cavity isn't needed any more.

(in other words bricks are a poor rainscreen and better to have a rainscreen
which is designed for that job in front of the bricks)

Theo