Nudura ICF and external cladding

[Martin S]

I'm being advised that it is no longer permissible to use Nudura Standard Series with 152mm concrete core under the revised Building Regs.  Does anyone have any experience of using this product under the revise3d Building Regs?

 

Also I have a combination of stone slip (40-50mm), wooden cladding (70mm) and Dryvit render (4mm) externally all with differing thickness.  What is the most cost effective way to achieve consistent wall depths when mixing these claddings?

 

Many thanks 

[nod]

I’m curious 

Why dryvit ? You will have to be careful for damage as it’s easily marked Looks virtually the same as Stucco But more expensive 

[Haylingbilly]

I am surprised to hear this - which revision of building regs are you referring to and why is it no longer permissible?

Have you looked into packing out the wall thickness with some EPS insulation?

[Martin S]

Min U-value for a wall is now 0.26 and Nudura Standard Series struggles to meet that even when factor in Dryvit 500 ICF rendering system externally and 12.5mm gypsum plasterboard with 3mm skim internally.

 

Am looking at Dryvit 500 ICF rendering system given its 30 year warranty when applied directly to Nudura ICF and the fact that it allows me to maximise my GIA given that it is only 4mm thick.  Are there other more cost effective alternatives to this that you can recommend offering similar warranty period?

 

Am looking into packing out with 3rd party EPS insulation but not sure how this affects BBA certification of Nudura ICF and if it precludes the use of the Dryvit 500 rendering system?

 

[Onacrame]

We also got the feedback that the standard forms would struggle to meet new building reg requirements so now we’re going with the plus series with an additional 50mm of insulation getting the u value to .18.

 

Martin how are you dealing with stone slips and warranty requirements.  I get the sense the warranty providers want some cavity between the slips and the EPS.  How are you affixing the slips?

[Nickfromwales]

On 04/01/2023 at 14:57, Martin S said:

I'm being advised that it is no longer permissible to use Nudura Standard Series with 152mm concrete core under the revised Building Regs.  Does anyone have any experience of using this product under the revise3d Building Regs?

 

Also I have a combination of stone slip (40-50mm), wooden cladding (70mm) and Dryvit render (4mm) externally all with differing thickness.  What is the most cost effective way to achieve consistent wall depths when mixing these claddings?

 

Many thanks 

Hi. When exactly did you make your application? Historic applications would permit you to carry on with the basic system.

[Martin S]

Hi Onacrame, is that the plus form with the additional insulation externally rather than inserts?  I'm being told by my Nudura distributor that it is hard to source and being quoted exorbitant prices.  How cost effective is it to use?  Have you used a mix of Nudura products to accommodate a mix of external cladding of varying depth?

 

Am not as far as engaging a warranty provider but was under the impression that you could affix cement building board and attach the stone slips to that.  Is that not acceptable?  

 

My planning permission was granted after the new building regs kicked in.

[Selfbuildnewbie]

@Martin S we are under the new regs and using Nudura. On its own the 0.24 u values of the standard Nudura blocks are permissible but are worse than the notional values in the regs, but we have passed the SAP compliance tests by increasing the insulation in the loft and floor. Another 100mm of loft roll and 25mm of celotex is considerably cheaper than upgrading the Nudura blocks or even adding more EPS to the walls. 

[Onacrame]

On 23/01/2023 at 13:24, Martin S said:

Hi Onacrame, is that the plus form with the additional insulation externally rather than inserts?  I'm being told by my Nudura distributor that it is hard to source and being quoted exorbitant prices.  How cost effective is it to use?  Have you used a mix of Nudura products to accommodate a mix of external cladding of varying depth?

 

Am not as far as engaging a warranty provider but was under the impression that you could affix cement building board and attach the stone slips to that.  Is that not acceptable?  

 

My planning permission was granted after the new building regs kicked in.

Actually we’re going to go for the XR35 now.  It’s about a third more expensive but it doesn’t change the labour costs.

 

Talking to warranty providers the best we’ve gotten from one is that they would accept a carrier board that’s mechanically fixed to the ICF like a Wetherby system.

Edited February 11, 2023 by Onacrame

[Martin S]

 

On 10/02/2023 at 08:01, Selfbuildnewbie said:

@Martin S we are under the new regs and using Nudura. On its own the 0.24 u values of the standard Nudura blocks are permissible but are worse than the notional values in the regs, but we have passed the SAP compliance tests by increasing the insulation in the loft and floor. Another 100mm of loft roll and 25mm of celotex is considerably cheaper than upgrading the Nudura blocks or even adding more EPS to the walls. 

Interesting. What SAP rating are you achieving for the walls and overall? We’re aiming for an A rating and understood that this is not possible with the entry level Nudura wall.

[Nickfromwales]

An interesting snippet, including the impact of summer overheating and mitigatory cooling ( subsequent ) energy costs.

Fails to specifically mention if PV is involved, but does take that into consideration ( given most shitty mass-produced development builds have some token PV to offset laborious and costly insulation programs )   God forbid they should do both  

 

 

How SAP works

SAP works by assessing how much energy a dwelling will consume when delivering a defined level of comfort and service provision. The assessment is based on standardised assumptions for occupancy and behaviour. This enables a like-for-like comparison of dwelling performance. Related factors, such as fuel costs and emissions of carbon dioxide (CO2), can be determined from the assessment.

SAP quantifies a dwelling’s performance in terms of:

• energy use per unit floor area
• a fuel-cost-based energy efficiency rating (the SAP Rating)
• emissions of CO2 (the Environmental Impact Rating)

These indicators of performance are based on estimates of annual energy consumption for the provision of space heating, domestic hot water, lighting and ventilation. Other SAP outputs include:

• estimate of appliance energy use
• the potential for overheating in summer
• the resultant cooling load

[Nickfromwales]

I suppose that Nudura will soon start selling more of the XR35 kit as people start to become aware that it is an option which would mitigate downstream laminations ( and the time / cost of doing so ).

[Martin S]

2 hours ago, Onacrame said:

Actually we’re going to go for the XR35 now.  It’s about a third more expensive but it doesn’t change the labour costs.

 

Talking to warranty providers the best we’ve gotten from one is that they would accept a carrier board that’s mechanically fixed to the ICF like a Wetherby system.

Am actually going with Polarwall ICF now as achieved better U-value for the money and could accommodate varying thicknesses of external insulation needed for my mix of cladding (render, stone and wood) without cost of additional 3rd party EWI.

Was hoping to attach carrier board directly to EPS using adhesive such as  base coat used for thin silicon render system without need for mechanical fixings.  Ideally I want to avoid drilling through the insulation.  No luck with this approach?

[Nickfromwales]

28 minutes ago, Martin S said:

Was hoping to attach carrier board directly to EPS using adhesive such as  base coat used for thin silicon render system without need for mechanical fixings.  Ideally I want to avoid drilling through the insulation.  No luck with this approach?

I would not like to be tasked with sticking sheets of render board to EPS! 

Does PW not have the embedded spines at 400 o/c like Nudura has eg for reliable mechanical fixing?

[Martin S]

I only have 10sq.m on ground floor to cover with Wild Stone or Z-clad stone panelling.  Yes PW has horizontal spines but BBA certs of both PW and Nudura suggest that may not be adequate alone for external cladding and may need mechanical fixing to concrete core too. That lead me to possibility of builders board being screwed into spines and stuck to the surface of the EPS.

[Russell griffiths]

@Martin S watch out for trying to attach stuff to polar wall, the nylon straps stand proud of the eps so you don’t have a flat surface. 

[Martin S]

Thanks, yes. Am going for the thicker external insulation so strap is embedded within the insulation.  Any pointers re thickness of internal insulation?  Am concerned about having to cut through strips when chasing electric cables.

[Conor]

Stick an extra 100mm EPS on the outside. Not much more cost than 50mm and same amount of work. You can use 180mm galvanised screws for fixing battens/ cladding through to the plastic web. For fitting the EPS, full bead of foam and 5/6 screws through to the web. Easy enough job. It's excacly what we did and far cheaper than higher spec ICF. No regrets.

 

(I happen to have a load of 180mm screws, caps and EPS plugs left over)

Edited February 11, 2023 by Conor

[Onacrame]

21 hours ago, Martin S said:

I only have 10sq.m on ground floor to cover with Wild Stone or Z-clad stone panelling.  Yes PW has horizontal spines but BBA certs of both PW and Nudura suggest that may not be adequate alone for external cladding and may need mechanical fixing to concrete core too. That lead me to possibility of builders board being screwed into spines and stuck to the surface of the EPS.

Hi do you have links to the Nudura BBA Certs re: cladding and mechanical fixing to concrete core.  Thanks!

[Martin S]

Hi Onacrame.  Here is the BBA Certificate, it only really covers fixing of internal plasterboard to the flanges rather than the concrete core.  

Nudura BBA Certificate Current.pdf

[John Keith]

XR35 blocks with 152mm concrete core. 0.16 u value