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Insulation advice for brick veneer upper level

(19 posts) (11 voices)

Started 5 months ago by mboy
Latest reply from jdaley

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mboy
Member

Hi all
I need some advice please?
Going through the process of building design for new home (Vic)
We come from an existing home with brick veneer downstairs and lightweight upstairs (polystyrene 100mm wallboard : according to previous owner ). I think upstairs has been well insulated

We have decided to go for complete brick veneer finish both upstairs and downstairs this time.

I read that from an insulation point of view, polystyrene wallboard is better than brick veneer.

Therefore what steps should I take to maximise brick veneer wall insulation?
1. Timber frame stud size: 90mm stud depth the minimum? Go for 140mm -more cost?
2. R2.5 batts in wall - go higher?
3. Anything extra products inside the wall - sisilation wrap? anything else?

Many thanks in advance
MB

PS - It will be too expensive for me to do cavity brick/double brick

Posted Friday 17 Nov 2017 @ 8:34:42 pm from IP #
Morbo
Member

the only function of the brick veneer is to look good. So why bother?

Posted Sunday 19 Nov 2017 @ 2:25:01 am from IP #
Annette
Member

Hi Mboy

I would ask your architect about this.

At what stage is the design - just concept or further?

Posted Sunday 19 Nov 2017 @ 10:01:12 am from IP #
Morbo
Member

timber frame doesall the work in conventional design.Including bracing the bricks from sideways movement. Bricks are just there so you dont have to paint. And if you have plenty eastern/western exposure they get up to 50+ degrees.

Posted Sunday 19 Nov 2017 @ 11:30:34 am from IP #
d.darroch
Member

Yep, brick is a high thermal mass material. Meaning it can store a lot of heat, releasing that heat once the ambient temperature cools down. So, not a good idea for the upper level, as it inhibits the upstairs bedrooms cooling off on summer evenings.

Posted Monday 20 Nov 2017 @ 12:48:06 pm from IP #
David
Member

mboy said:
I read that from an insulation point of view, polystyrene wallboard is better than brick veneer.

if it's on the outside technically it is, but you are better off going considerably thicker 150mm, 200mm and then cladding in metal is much better than rendering over it will last way longer, with much less long term issues, or other options that will out perform and last better.

mboy said:
Therefore what steps should I take to maximise brick veneer wall insulation?
1. Timber frame stud size: 90mm stud depth the minimum? Go for 140mm -more cost?
2. R2.5 batts in wall - go higher?
3. Anything extra products inside the wall - sisilation wrap? anything else?

1. Skip brick veneer altogether for the whole building, do the walls at least 250mm+ in thickness clad it in sheet metal with a decently sized eves, add R6-batts (glass type which are classed as life of the building) along with applicable wrap and then thin metal battens gives a small gap between the wrap and the metal cladding. Virtually maintenance free.

2. R2.5 in the walls good for interior walls and worth doing, for interior walls. No eaves basically offsets the lack of eves and reduces heat loss in winter, otherwise quite poor in performance. For exterior walls you really want much thicker particularly a BV house to offset heat soak. We are hot country and need to ensure we design buildings properly for heat resistance, high levels of insulation is one way that is not OTT to do this, will also reduce cooling demands, now one the highest power costs we have to the home owners pocket.

3. Wall wrap and insulation and ensure that any penetrations are sealed up and properly around the reason for the penetration. They offer considerable heat soak in both directions depending on the temps outside/inside and ruin the "star" rating if this is not done.

Bricks are a weather protection system for the outside of a building they do not support the building in a brick veneer house and they do not support the roof.

Avoid a tile roof, design the roof to be ideal to install solar PV on it, install at least R6 or higher rating insulation in the roof cavity, make the roof solar installation friendly means large areas without all sorts of angles/corners on it, that severely limits the installation of solar ensure you orient the house/roof to optimize the install of it, hip rooves can potentially limit the installation of a decent amount of solar unless they are big enough. Ensure the angle of the roof areas is steep enough ie at least 25 degree or preferably more, or do a flat roof and use tilt framing for solar on it, go for white roof ideally, good coverage with Solar can also reduce the amount of heat that soaks into house if the house is designed correctly it can reduce heat soak into the building by upto 10C compared to not having it in place.

The way houses are designed ATM for most "spec builders" is to a price, then easy to meet council often silly aesthetics rules, then the star rating. If you are bold go for really smart design, you don't have to have an architect, but you do have understand what a house really should have to be cool in our hot climate and warm in our mild winters to be a really great house. High thermal mass on the outside (bricks) is not ideal, designed well might be a bit more expensive but it does not have to cost the earth.

Posted Monday 20 Nov 2017 @ 8:31:54 pm from IP #
Johnnojack
Member

I'd advise strongly against brick veneer upstairs at least. Useless as insulation, good for transferring heat to the inside after dark on hot nights. You will need bigger footing and heavy steel lintels above the lower windows to support the brickwork. Why don't you want to use the rendered polystyrene again? Wasn't it done very well on the existing house? To get the equivalent insulation value you'd need 140mm stud work plus sisalation wrap at least. That said I have yet to see thicker studs done properly, 120mm studs with 140mm batts forced in is not the way to go. I agree with what David has said however you could use cement based cladding such as Matrix, Scyon or similar products to get a low maintenance cladding instead of steel.

Posted Monday 20 Nov 2017 @ 10:56:28 pm from IP #
mboy
Member

Thanks all for your help, I love the 1st Morbo comment that sums it all up.
I am the design phase so wanting to equip myself with knowledge with the designer

I guess I have to let go of my desire for brick, based very much on growing up with brick being the cladding back in 1970s to 1990s.

My land is east-west facing so the the majority surface area of walls will be N-S.

I really appreciate the opinions of at least no brick upstairs and the thermal mass slowing down cooling of a summer day. I admit the upstairs of our current house which is polystyrene is quite comfortable in the summer nights.

My initial fears/concerns about doing polystyrene again stem from what I have seen in our house - granted, it could all be due to time and weather worn. Our current house is 12 years old, I can see the seam tape showing the gaps, the render looking different when it transitions from brick to polystyrene, chips of render at the edges/corners, the large gaps present at the interface with the 1st floor polystyrene walls and roofing. Maybe its the poor install, poor render material and northern walls show most effect given prolonged sun-exposure. Also having to accept needing higher maintenance with render, and re-rendering again - seems so soon at 12 years.

Thanks David for some of the suggestions regarding passive design, especially advice on roof design and solar installation friendly.

Johnno: your comment about getting 'equivalent insulation' for brick veneer: if you could get 140mm studs with 140mm batts, with wrap: that still wont be ideal to insulation internally when the thermal mass has accrued heat in the bricks during the day?

Thanks all!

Posted Tuesday 21 Nov 2017 @ 11:32:55 am from IP #
dave lawrence
Member

I can understand your reluctance to not use brick upstairs.
It is expensive ,if not installed and detailed well it is not useful for energy efficiency purposes ,but it does have many attributes that other more popular and trendy building systems lack , namely extreme durability and low maintenance over many years .
I am not a great fan of brick houses myself , I am aware of their insulation limitations and heat sink liabilities.. but with intelligent design these issues can be minimised.
But I would never contemplate using polystyrene for building a house. durability - minimal . flammability - extreme. eco-credentials ... dubious .
It will be interesting to see how long the trend of those products last .
brick houses have been around a very long time... there is a reason for that... they last .

Posted Tuesday 21 Nov 2017 @ 7:43:24 pm from IP #
mboy
Member

Dave, thanks for providing an alternative view on brick. Your comment about intelligent design to compensate for the insulation limitations of brick/thermal mass/heat sink is some hope that brick is not all bad from passive design point of view.

I found this weblink, http://www.ttarchitecture.com.au/advice/externalWalls.html
and if I read correctly:
1. brick veneer with insulation R value: 2-3.5
2. polystyrene foam ~ R 3.5
3. hebel R 2.5

so the extra performance of say hebel is slightly more than the worst case insulation brick veneer.

I wonder if there are any ways to minimise the heatsink effect of brick in summer by putting in extra materials in the wall space : theremo-reflective insulation. The day-night temperature difference in spring/summer can be dramatic

Thanks again
MB

Posted Wednesday 22 Nov 2017 @ 11:13:26 am from IP #
dave lawrence
Member

Hi MB , yes there are purpose designed sarking insulating materials ... look at aircell for cavity brick . But as always with building design, you should not rely on just one line of defence ,and still have appropriate eaves, shading devices and bulk insulation to stud frame as well.
Personally I would not recommend brick at two storey level , but feel it is often maligned by the anti brick brigade without their really understanding the whole story .

Posted Wednesday 22 Nov 2017 @ 7:43:26 pm from IP #
Ruffy
Member

As already mentioned, brick veneer is just for the look (thus 'veneer'). Also, the thermal mass properties of the brick are effectively lost as they are on the exterior building surface and thus conductively insulated from the building envelope by the R2.5 batts in the stud frame, and radiatively insulated by the sarking. It's more expensive and not many builders do it, but reverse brick veneer makes a lot more sense as you encapsulate the thermal mass properties of the bricks inside the building envelope and insulate them from the environment outside.

R6 in the walls would be great, but it's a bit of overkill in this climate IMO, especially if you are having to over-engineer the structure to fit the 25cm+ thick batts. R5 ceiling system value and R3 wall and floors (brick veneer wall + R2.5 batts + other wall system elements has a total system value of R3.0-3.4) will do the job in Aus as we don't get the extreme delta-Ts of colder climates. Typically our delta-Ts don't exceed 25C in winter (eg. -5C outside, 20C inside or 20C inside 45C outside - and these are extremes not often encountered).

A comment on summer - 80%+ of heat gain to a properly insulated and sealed building will come as radiant heat through the windows, so shading of all east-west-north-facing windows to prevent sunlight ingress is crucial to address summer heat. When considering heat entering or leaving a building it is extremely important to understand the KIND of heat - is it radiant or conducted? If it's the former, mirror or shade, for the latter bulk insulate or double-glaze. And of course properly draught sealing the building helps in both seasons - its effect is often underestimated and poorly executed in Aus as we do not have compulsory leak testing.

Posted Tuesday 28 Nov 2017 @ 12:36:06 am from IP #
mboy
Member

Just continuing this post with some recent dealings I've had with a building designer.
He has designed and built many houses and feels that a brick veneer house which is well designed and very well insulated is comparable to many of the lightweight materials including Hebel and polystyrene foam, in terms of thermal insulation.

I did further press him on brick being a heatsink and dissipating heat inside the house during summer and he felt this could be minimised and comparable to lightweight.

Mb

Posted Saturday 16 Dec 2017 @ 8:24:50 pm from IP #
AndyG
Member

I do agree that polystyrene is rubbish as a cladding (excellent in theory, yet to see a system that is well thought out IMO), but I wouldn't go with B/V either.

Don't forget that the extra weight of the brickwork upstairs needs to be supported somehow (i.e. extra $'s) and brickwork is ridiculously sensitive to cracking with any kind of movement in its supporting structure (i.e. any deflection must be kept below span/1000)

I went with a composite aluminium cladding (fire retardant obviously!) that actually reflects the heat on the western walls of my bedrooms, and that along with R6 ceiling batts and R2.7 walls, plus a very well sealed construction means we have yet to swelter at night (been here almost 3 years) and normally even the ceiling fans make it a bit too cool even in summer when you're trying to sleep.

Posted Saturday 23 Dec 2017 @ 7:05:34 am from IP #
mboy
Member

I've been around to so many builders, and even the high end will still use polystyrene upstairs, so it can't be that bad or wrong to use.
I agree brick veneer upstairs is more sensitive to cracking: probably very obvious if you rendered brick upstairs.
How nice to get a house design that is well insulated that you dont get exposed to the outside extreme weather!

Posted Sunday 24 Dec 2017 @ 8:52:59 pm from IP #
Johnnojack
Member

Mboy the figures you quoted in your post on 22 Nov are misleading, that compares Hebel blocks with no extra insulation against brick veneer with insulation. Most builders use Hebel panel with an almost identical frame to brick veneer. (with the bulk insulation) so with Hebel rating at R1.1 and brick a R0.1 Hebel is clearly better.
Also foam is not really rubbish but some foam installations are rubbish. With rendered brick or Hebel on the ground floor and rendered foam above you can't get an invisible joint, the best way is to have horizontal board covering a wide expansion joint. Make sure that control joints are done properly and not left out. Insist on 75mm foam not 50mm.

Posted Monday 25 Dec 2017 @ 7:18:18 am from IP #
decerebrated
Member

We have 100mm Unitex polystyrene upstairs and after 7 years it still looks like new. If the seam tape was showing on the house you have experience with then the installers didn't put enough render on.

Posted Tuesday 26 Dec 2017 @ 8:56:55 am from IP #
mboy
Member

Thanks JJ for correcting me. It didn't mesh right when hebel already has superior R value than brick, and the figures quoted didnt account for insulation of the cavity wall you can do with hebel. I wonder thought if you maxxed out the insulation in the cavity wall, how much extra benefit the thermal benefit of hebel has over brick.

Its interesting with our existing property. We do have the horizontal board hiding the seam between the downstairs brick and upstairs foam. When you look at one wall on the other side where the upper floor foam sits against the ground floor garage roof: there is a gap with foam edge exposed. Probably poor install and is consistent with the exposed seam tape we are seeing. In defence of the builder, this exposed seam tape wall is exposed to northern sun at its been 13 years so its due for a re-render anyway.

Posted Friday 29 Dec 2017 @ 4:55:30 am from IP #
jdaley
Member

The cracking and joints showing in these modern finishes IMO, should exclude them being used as the external finish.
But somehow and inferior finish seems acceptable. If as suggested you apply a steel or cement sheet product sheet over the poly wall strutter it should be perfect.
Davids suggestion is the best system to use today.
The technology works.

Posted Friday 29 Dec 2017 @ 11:37:47 pm from IP #

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