Retrofit dry blown wall insulation - Anyone here with experience?

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#1828824 25-Jul-2017 09:42

And thinking about it further. If I understand right, the insulation will be contained on one side by brick, the other by gib board (?) with the studs in between? The worst case scenario is that it does block up the cavity and you get moisture retained inside the walls. I would have thought that the gib would go mushy well before any of the studs started to rot? Cold comfort I guess, but it's relatively easy to replace gib and pull all the stuff out if you notice a problem. Reframing an entire house, not so much.

Wheelbarrow01

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#1830451 26-Jul-2017 08:01

mdf:

And thinking about it further. If I understand right, the insulation will be contained on one side by brick, the other by gib board (?) with the studs in between? The worst case scenario is that it does block up the cavity and you get moisture retained inside the walls. I would have thought that the gib would go mushy well before any of the studs started to rot? Cold comfort I guess, but it's relatively easy to replace gib and pull all the stuff out if you notice a problem. Reframing an entire house, not so much.

Yes your understanding is correct - this product fills the entire space between the gib and the brick cladding. Initially I was concerned about moisture retention, but they assure me the product is fully breathable and due to the fact that the product repels water and will not hold it, I am starting to feel pretty optimistic, especially after playing around with the sample they left me. After watching it float on top of a glass of water for over a week, I removed it and gave it a squeeze. No water came out of it. This makes me pretty confident that if any water vapour were to get into the product, it would naturally disperse, and if any actual water were to come into contact on the cladding side, gravity would assist it to drop vertically rather than it spreading laterally to the framework. The demo video on their website appeared to conclusively show this as well.

Before I make a decision, I am going to ask the company if they can refer me to a previous customer so I can see the results of the installation - ie I want to see a brick veneer house that they have insulated, as I want to check just how 'invisible' the installation really is. My repointed and painted brickwork is immaculate so I just want to ensure that where they drill, fill and paint is not going to be too noticeable.

The quoted price of just over $5k is within my budget, and with every morning in my house feeling colder than the last, I am keen to sort my heat retention issues out once and for all.

nickb800

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#1832892 28-Jul-2017 13:59

The impact on your electrical wiring is worth considering too - both reducing the safe capacity of cables in the wall, and getting into the back of switches/sockets

https://www.electricalforum.co.nz/index.php?action=more_details&id=1500977096

mattwnz

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#1832935 28-Jul-2017 14:53

nickb800:

mattwnz:

I think there is a bit of confusion here. Are they wanting to install it in the actual framing cavity (where normally insulation should go). Or are they wanting to install in the cavity between the back of the brick, and the front of the framing, which is infront of the building wrap? The retrofit systems I have seem always go in the actual framing, which will also provide a far thicker insulation layer. Usually the problem with systems that are loose, is they can compact down over time, leaving uninsulated patches at the top. You can get the same problem with normal wool insulation too.

It goes in both the framing cavity and the brick cavity - they are effectively one cavity as there is no building paper or wrap in houses of this type from this era

In that case I wonder if it is suitable for that type of construction, as the brick relies on the cavity at the back to drain? The other think IMO is that it could bridge the cavity meaning water such as condensation from the brick inner surface, could come in contact with timber by capillary action across the cavity. Has there been a branz report, or test for that particular situation, and to see how it performs over time?

Fred99

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#1832941 28-Jul-2017 15:07

mattwnz:

nickb800:

mattwnz:

I think there is a bit of confusion here. Are they wanting to install it in the actual framing cavity (where normally insulation should go). Or are they wanting to install in the cavity between the back of the brick, and the front of the framing, which is infront of the building wrap? The retrofit systems I have seem always go in the actual framing, which will also provide a far thicker insulation layer. Usually the problem with systems that are loose, is they can compact down over time, leaving uninsulated patches at the top. You can get the same problem with normal wool insulation too.

It goes in both the framing cavity and the brick cavity - they are effectively one cavity as there is no building paper or wrap in houses of this type from this era

In that case I wonder if it is suitable for that type of construction, as the brick relies on the cavity at the back to drain? The other think IMO is that it could bridge the cavity meaning water such as condensation from the brick inner surface, could come in contact with timber by capillary action across the cavity. Has there been a branz report, or test for that particular situation, and to see how it performs over time?

That's discussed in the MBIE determination I linked to above in this thread, where in that case they accepted that the product wouldn't wick water from the brick through to the framing.

From what little information I could find, the water-repellent properties of the mineral wool are imparted by treatment with a silicone polymer. I have no idea how durable that treatment would be - whether it would break down over time or whether dust etc setting on or in it would affect it.

The maker makes claims about the product being used for retrofitting insulation in Europe. Some more information on that would be nice - ie where in Europe, and to retrofit insulation to brick-veneer / timber framed structures - filling the entire cavity as above - or as common in Europe, filling the cavity in old double-brick construction.

Fred99

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#1832942 28-Jul-2017 15:08

How much does it cost?

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mattwnz

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#1832952 28-Jul-2017 15:36

I was referring more to brick veneer that isn't painted and sealed because most won't be.

I wasn't referring to wicking of moisture, but it actually traveling down and between the material. Because it is an obstruction I don't think iwater will fall straight down. A bit like those gravity games with pins where the ball dropped in the top potentially can get moved across sideways by the obstructing pins.

Wheelbarrow01

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#1832956 28-Jul-2017 15:46

mattwnz:

nickb800:

mattwnz:

I think there is a bit of confusion here. Are they wanting to install it in the actual framing cavity (where normally insulation should go). Or are they wanting to install in the cavity between the back of the brick, and the front of the framing, which is infront of the building wrap? The retrofit systems I have seem always go in the actual framing, which will also provide a far thicker insulation layer. Usually the problem with systems that are loose, is they can compact down over time, leaving uninsulated patches at the top. You can get the same problem with normal wool insulation too.

It goes in both the framing cavity and the brick cavity - they are effectively one cavity as there is no building paper or wrap in houses of this type from this era

In that case I wonder if it is suitable for that type of construction, as the brick relies on the cavity at the back to drain? The other think IMO is that it could bridge the cavity meaning water such as condensation from the brick inner surface, could come in contact with timber by capillary action across the cavity. Has there been a branz report, or test for that particular situation, and to see how it performs over time?

The insulation being offered to me is Supafil 40 by Knauf. This product is covered by British Board of Agrément Certificate 88/2033:

Moisture resistance

Tests by the British Board of Agrément confirm that Supafil® 40 Cavity Wall Insulation will not transmit water to the inner leaf. Nor will it transmit moisture by capillary action across the cavity or from below damp proof course level. This has been confirmed by independent research conducted for the Energy Saving Trust which shows that this cavity wall insulation does not add to the risk of water penetration.

Vapour resistivity

Supafil® 40 Cavity Wall Insulation offers negligible resistance to the passage of water vapour and has a water vapour resistivity of 5.00 MN.s.g.m.

I know these are not NZ standards or testing authorities, but it is enough for me to be satisfied that there is no threat to the building envelope. As I have said in previous posts, I had a sample of the product in a glass of water on my bench for a week. It did not absorb water even when I tried to forcibly immerse it, and it floated on top of the water for an entire week. When I took it out and squeezed it, there was no water in it.

Fred99

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#1832957 28-Jul-2017 15:46

mattwnz: I want referring to wicking of moisture but it actually traveling between the material.

I think that's kind of covered in the data. It surprises me a bit that water couldn't track. Also if the inside of the brick was damp, then as airflow must be reduced, condensation could form on the framing. There's not a huge margin between moisture content in dry timber - and the point at which decay can start.

Fred99

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#1832959 28-Jul-2017 15:55

OK - so now we know something about the product:

Note that UK approval is for masonry cavity walls - not the cavity in timber-frame brick veneer construction.

The UK certification really isn't relevant to the proposed use in NZ - it would be better if the seller of the system didn't use it in sales literature, in my somewhat pedantic opinion.

Wheelbarrow01

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#1832960 28-Jul-2017 15:57

Fred99:

How much does it cost?

The don't give out a rate per square/cubic metre, but my house is around 105 square metres with a 150mm cavity (plus the width of the framing). The quote for my house is $5700 inc gst, and includes the cost of painting over the exterior holes in my brick cladding after they have sealed them (my bricks are already painted with white elastomeric paint and I have some left over).

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Fred99

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#1832963 28-Jul-2017 16:04

OK - is the brickwork in good condition - and the same for internal wall linings?

If either needed attention, then I'd be wondering if insulating using that system now could be false economy - if either re-gibbing or re-cladding was something coming up.

Does the $5700 estimate include cost for consent, inspection, CCC etc. ?

mattwnz

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#1832984 28-Jul-2017 16:38

Fred99:

Note that UK approval is for masonry cavity walls - not the cavity in timber-frame brick veneer construction.

The UK certification really isn't relevant to the proposed use in NZ - it would be better if the seller of the system didn't use it in sales literature, in my somewhat pedantic opinion.

NZ does have some houses with double wall brick houses, but they will be very old, and those are the type that fell down in the quakes, as they have very little EQ resistance. These days brick is purely a skin that goes over a timber a frame with drainage cavity inbetween. With newer houses, the timber should have H3 or better protection. Old houses from 50's can have rimu framing, which may not offer the same protection.. However the brick veneer on some of these older houses isn't actually tied to the framing like it is on newer houses, so in a earthquake, the cladding can just came away from the walls. The Edgecome earthquake I beleive resulted ina lot of changes to brick veneer building after many failed. So I would find out whether that is the case or not with your walls. If something is forced in, it potentially could force the brick wall outwards if there is enough pressure, and the brick isn't tied back.

I think it largely comes down to the council, and whether they are comfortable with the system being installed, as they are the ones who will have to sign it off.

Also I think if anyone is drilling holes in bricks to install it,, the should angle the drilling upwards. So if the mortar fill does crack, the water then has to travel upwards, which isn't as easy as sideways. Although capillary action from a crack can still pull water upwards.

mattwnz

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#1833009 28-Jul-2017 16:47

Fred99:

OK - is the brickwork in good condition - and the same for internal wall linings?

If either needed attention, then I'd be wondering if insulating using that system now could be false economy - if either re-gibbing or re-cladding was something coming up.

Does the $5700 estimate include cost for consent, inspection, CCC etc. ?

Regibbing does also mean that potentially they could install insulation with a better R value in the walls, and means they can install building paper and something behind it to stop the cavity being compromised. Although insulating in the cavity with this system potentially does allow for a thicker insulation with a higher R value.

The system does look to have a Codemark in NZ

Fred99

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#1833020 28-Jul-2017 16:58

mattwnz:

However the brick veneer on some of these older houses isn't actually tied to the framing like it is on newer houses, so in a earthquake, the cladding can just came away from the walls. The Edgecome earthquake I beleive resulted ina lot of changes to brick veneer building after many failed.

Our place (1962) had brick veneer cladding, the old 4 1/4 inch red brick type, though it also had good cement mortar and plenty of tiebacks. Like anything brick in our neighbourhood, it was an abject disaster when tested by the Chch quakes. The tiebacks actually didn't fail and the bricks didn't fail only on mortar lines, but cracked straight through the face of the bricks - so we had a house clad in wobbly panels of fractured brick, with bits falling off with each aftershock.

It might have fared a bit better with modern 70mm brick and the metal strap tiebacks they use now, but IMO primarily because of the much lower mass of modern bricks. EQC and insurer wanted to re-brick it. I didn't - once bitten twice shy as they say. I cash-settled with them - and that was the main reason - there's no way I wanted it re-clad in brick.

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