Partel » Thermal bridge http://www.partel.ie/blog Passive building supplies Fri, 10 Mar 2017 00:14:05 +0000 en-US hourly 1 http://wordpress.org/?v=3.5.1 Ampatex® LDA 0.02 plus – Renovation Vapour check http://www.partel.ie/blog/?p=465 http://www.partel.ie/blog/?p=465#comments Wed, 02 Sep 2015 21:48:59 +0000 Hugh http://www.partel.ie/blog/?p=465 Ampatex® LDA 0.02 plus - Renovation Vapour check

What is it and why is it changing how we upgrade older homes?

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We are used to seeing SD values in airtight membranes – LDA is different in that it lists an a value – 0.004m3/(h*m2).  The a value describes the quantity of air passing through the layer. (The SD vale relates to the humidity or vapour). While the a value is not currently a defined standard the reference value in the industry for an airtight layer is <0.01m3/m2/h.

 

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This solution starts with higher humiditys and the quality of application is (As it is with all VCL’s) important. To assist with this AMPACK have include integrated tapes on both sides of the membrane and has the same incredible strength we have become accustomed to from AMPACKs exterior membranes.

 

When we consider quality of application is is important to understand why – a 1mm wide gap can allow 360g water per day – such errors can create issues in any VCL system and as always we recommend a blower door test. In this case it should be carried out when LDA has been installed and before the windtight membrane (PROTECTA is installed).

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With AMPACK this is a system solution – below you can see that LDA is compatible with BBA certified Protecta and its associated rane – XT, and Superfix.
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From a technical point of view the thickness of the SCHNEIDER Woodfibre insulation plays an important part – We analysed the systems for the demonstrated room in WUFI and found that 35mm of woodfibre was insufficient and led to unacceptable water content for short periods – when we increased the system as below – 60mm woodfibre or more the system is within acceptable parameters. We recommend that 80mm of SCHNEIDER 140 multitherm be installed generally.
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This system has obvious benefits in addition to airtightness as it achieves a thermal bridge free roof, offers excellent decrement delay (Keeps house cool in the summer) and actually sequesters carbon.

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