Composite Wall Ties - Worth the extra cost?

[Matt60]

Hi,

 

I have calculated that I will need roughly 1500 wall ties and have been looking at composite ones to avoid thermal bridging. The cost difference is £2430 verses £555 for stainless steel versions. That price seems crazy to me but the house is a keeper and I'm trying to do the fabric of the build to a good spec.

 

I'm building a 150mm cavity with full fill Dritherm 32 insulation, good air-tightness and a MVHR.

 

1500 pieces of steel that span from inner or outer cavity sounds a lot but then, the total surface area is not that big.

 

Does anyone know if these are worth pursuing for near 5 times the cost of steel, near £1900 extra?

 

Thanks in advance.

[PeterW]

What is your overall wall build up..? Inside to outside ..?

[Dudda]

In you're case no. What's the build up of the walls? See below example I've done for you.

 

[saveasteading]

It had never occurred to me that wall tie conduction was significant. Now seeing the extra cost it would take a lot of lost energy to recover that  cost.

 

So I wouldn't change from the norm.

 

If it makes a huge difference, I would expect Ancon to have done tests and made the case.

 

I remember once working out the heat loss through screws in an industrial roof. They are going from the hex head outside in the weather, right  through to the roof rails, via other metal bits. It was surprisingly little heat loss, and complex to find a sensible alternative.

 

The standard wall U values as calculated, presumably included wall ties, so the loss is already accounted for.

[Matt60]

@PeterW & @Dudda

 

It will mainly be K-Render, 100mm 3.6n Outer block, 150mm full fill Dritherm32 and then 3.6n aircrete type inner block, slurry coated with dot and full width dabs, socket cavities sealed etc. Very similar to what you have posted Dudda.

 

The ties I was looking at are the Ancon BF2 that show a 0.7 W/m2K rating but I don't really know 0.14 difference is worth having. I'm guessing that as that is a Watts per meter squared (and the total area of these ties must be significantly less that that) that it would be a total waste of £1900 extra? Is that right?

 Ties for Brick-to-Block Construction | Ancon 

 

Thanks for your replies.

[Mr Punter]

Not worth it.  Save the money.  The ties will be the equivalent of 100mm x 100mm area and as they don't go from outside temp to heated space they will have almost no impact.

[joe90]

My build is similar to yours but with 200mm cavity and dritherm and I discounted them as it will make min difference, on another thread they talk about making your own and buying the rods in length (can’t remember the thread ?‍♂️) and very much cheaper than specific wall ties.

[Matt60]

Thanks for the replies, certainly from what I'm able to ascertain, I think you're right. I've had some stainless ones priced and the difference is now £2000 less, that's a huge difference. I'll put that £2k towards my heating and PV system I think.

 

Thanks again,

 

Matt.

[gravelrash]

Metal ties are cheapish for 150mm cavity, any bigger and you struggle to find any cost effective solution. Joe 90 is referring to Basalt fibre reinforcing bar that is the same spec as Teplo composite ties and it can be bought very cheap, and the reason I have taken that route as 365mm ties are rarer than hens teeth and can cost upwards of £3 each.

[Conor]

I'd spend the £2k saving on the steel ties and spent it on an extra 50mm PIR in your floor or roof... much bigger benefit.

[MortarThePoint]

Take a look at the thread below. I don't think they're worth it. Thermally broken lintels probably a better choice

 

https://forum.buildhub.org.uk/topic/15192-dont-forget-thermal-bridging/

[Matt60]

On 26/05/2021 at 13:48, MortarThePoint said:

Take a look at the thread below. I don't think they're worth it. Thermally broken lintels probably a better choice

 

https://forum.buildhub.org.uk/topic/15192-dont-forget-thermal-bridging/

 

Thanks, by coincidence I ordered all my thermally broken lintels today. ?

[GEO-PAR]

On 26/05/2021 at 12:52, gravelrash said:

Metal ties are cheapish for 150mm cavity, any bigger and you struggle to find any cost effective solution. Joe 90 is referring to Basalt fibre reinforcing bar that is the same spec as Teplo composite ties and it can be bought very cheap, and the reason I have taken that route as 365mm ties are rarer than hens teeth and can cost upwards of £3 each.

Is there any particular size/type of Basalt fibre rebar I need to look for?  Currently going through the same process where I'm struggling to justify the cost uplift of extra wide cavity wall ties (375mm cavity) and this seems like a great solution.  How did you get over the lack of drip detail?   

[gravelrash]

I used 6mm sand coated basalt from Orlimex UK Limited. they supplied in 2.5m lengths then just cut them to length and install an o ring in the middle as a drip. They costed out at 22p each.

[Mr Punter]

48 minutes ago, gravelrash said:

I used 6mm sand coated basalt from Orlimex UK Limited. they supplied in 2.5m lengths then just cut them to length and install an o ring in the middle as a drip. They costed out at 22p each.

 

I had a look and they seemed to deal in board products.  Were the wall ties BBA or equivalent?

[gravelrash]

https://orlitech.co.uk     Christopher.Hirst@orlimex.co.uk

No BBA cert...That's why they cost so much from TEPLO.  My structural engineer jus checked spec and signed them off.