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Brick without visible mortar joints - Alternative to Vandersanden Group - Zero® brick,


squealeyhealey

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25 minutes ago, Triassic said:

This is nothing new, the Victorians were doing it and you can buy thin joint mortar. So why not choose a standard brick and buy the thin joint mortar and you away! No need for expensive special bricks.

 

https://www.pozament.co.uk/products/thin-joint-mortar/

 

 

 

From memory you also need to use stainless fish tail ties as they will fit in the joints. It does make coursing a bit of fun but works better when you use old imperial size bricks as they take up the gaps that would be mortar joints. 

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On 26/09/2018 at 07:57, PeterW said:

 

From memory you also need to use stainless fish tail ties as they will fit in the joints. It does make coursing a bit of fun but works better when you use old imperial size bricks as they take up the gaps that would be mortar joints. 

 

Thanks Guys -Yeah I suspect tin joint mortar would be more cost effective.

 

Do you have more details of how stainless fish tail ties will fit in the joints, the concerns with coursing and how imperial size bricks help.  Unfortunately I've not the knowlege / experience to appreciate how your suggestion will work.

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It’s to do with block sizes. 

 

A block is 215mm tall, 225mm with a mortar joint. A standard brick is 65mm tall, 75mm with a mortar joint. That means a block equals 3 bricks. 

 

Imperials are 73-76mm tall so with a  thin joint of 2mm you will end up at 75-78mm, or 225-235mm per 3 brick courses so that is roughly similar. 

 

You would probably need something like this but the manufacturer would need to confirm - not cheap !

 

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On 11/10/2018 at 21:14, PeterW said:

You would probably need something like this but the manufacturer would need to confirm - not cheap !

 

Thanks for the explination, unfortunately the thin wall ties that you sugget would form cold bridges.  I'm planning a passive house using basalt low thermal conductivity wall ties (Really not cheap) - Zero® bricks have a recess which will accomodate thicker wall ties. 

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Ok .... wall ties at 4/m2 would take up 0.0036% of a wall, so using something 100 times more conductive would mean that in a wall with a total u Value of 0.1 W/mK, the use of stainless vs basalt would take about 800-1000 years to repay the difference in cost...

 

There are bigger problems than what a wall tie is made of - air permeability being the major one that is easy to design out and has significant benefit overall. 

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23 hours ago, PeterW said:

Ok .... wall ties at 4/m2 would take up 0.0036% of a wall, so using something 100 times more conductive would mean that in a wall with a total u Value of 0.1 W/mK, the use of stainless vs basalt would take about 800-1000 years to repay the difference in cost...

There are bigger problems than what a wall tie is made of - air permeability being the major one that is easy to design out and has significant benefit overall. 

Yeah, I accept that some individual items to achieve passive are expensive, but I'm thinking that;- The benefits achieved from the building as a whole will be geater than the individual parts & The value of the building will be enhanced by the passive acreditation.  Denby Dale / Green building store passive houses seem to be cost effective overall. But I'm also aware of critisims of the cost effectiveness of passive standards.

Agree entirely about air permeability and as mentioned previously I'm planning breathable walls comprising Brick outter skin, air gap, breathable membrane, rock wool insulation, block inner walls & lime plaster.

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Our house slightly exceeds the PassivHaus standard, but isn't a certificated PassivHaus; I just used the same principles and didn't bother to pay the significant premium for accreditation.  We have had it valued and the valuer knocked 5% off the normal market value because it was a passive house and so unlikely to appeal to as wide a market.  When I questioned him about this he said that most people aren't interested in a house with low running cost, they are more interested in the bling in the kitchen and would be put off by there not being a "proper boiler and heating system".

 

Overall, the fabric build cost of building to a passive standard was around 10% less than a traditional block and brick house, according to one architect who came to see the house and asked me if he could have the cost breakdown.  Most of that saving was from the reduced labour cost in choosing a build system that went up very quickly and was weatherproof within a few days of starting.

 

There is very definitely a law of diminishing returns when it comes to improving thermal efficiency.  In our case we opted to accept wall U values of 0.12 W/m².K, rather than try and reach my goal of 0.1 W/m².K, as the difference was so tiny as to not be worth worrying about; the house still exceeded the PassivHaus requirements, as things like the doors and windows had a massively greater impact on heat loss.  Good airtightness is definitely critical, though, but doors and windows will most probably be the single greatest source of heat loss by a significant margin.  Our ventilation heat loss (better than PH airtightness and MVHR) is around half the heat loss from the windows, and that's with windows that have a Uw of around 0.7 W/m².K.  The heat loss through all our walls is around 30% higher than the window heat loss, but even if we had opted to get the walls down to the target of 0.1 W/m².K then they would still have had a leat loss of around 10% greater than the windows, and we were clearly into the law of diminishing returns from the loss of internal volume we'd have had from making the walls any thicker.

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@JSHarris, and you were fortunate in being able to design a home with a good low form factor*. Form factor is a crucial factor if Passive House is the goal and can be over looked.

 

(The form factor of the house I am planning, a bungalow because of site constraints, will make achieving Passive House more of a challenge. But I still consider it worthwhile. For me, the Passive-House approach is for comfort before efficiency.)

 

* form factor is the ratio of floor area to external surface area.

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7 minutes ago, Dreadnaught said:

@JSHarris, and you were fortunate in being able to design a home with a good low form factor*. Form factor is a crucial factor if Passive House is the goal and can be over looked.

 

(The form factor of the house I am planning, a bungalow because of site constraints, will make achieving Passive House more of a challenge. But I still consider it worthwhile. For me, the Passive-House approach is for comfort before efficiency.)

 

* form factor is the ratio of floor area to external surface area.

 

Not really that good, as being room in roof with a big gable sticking out the middle we ended up with a fair bit more ceiling and wall area than we  could have had if we had been able to build a conventional two storey house on the same footprint, plus the first floor area is smaller than the ground floor.  Planning constraints on ridge height ruled that out, as the planners had originally approved a bungalow for the plot. 

 

I agree that single storey houses do present more of a challenge, but to balance that it's often easier to incorporate more ceiling/loft insulation than it is to use more wall insulation, in terms of lost living space.  Being single storey needn't be that much of a disadvantage, as long as the area/perimeter ratio is reasonable.

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