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| Green Building Bible, Fourth Edition |
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These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment. PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book. |
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Posted By: ringiI was thinking that if the foam gun is pushed ALL the way to the back of each joint between EPS sheets then the foam would seal round each sheet to the wall, so stop air movements behind the sheets of EPS.Exactly - and all the fixing cement kept well away from block edges so no danger of it squishing into the joint.
Posted By: Peter_in_Hungarydriven by the (greater) buoyancy of the higher temperature air [I'd add, within the wall sandwich]then let's call it convection.
Posted By: fostertomand crosswise wind pressureWhat do you think drives wind, then? Convection works on quite a lot of different scales.
Posted By: djhYour EPS, Ed, looks like packaging, which I think is typically a finer (less expanded?) variant than EPS70. I don't know whether that would make any difference.Yes, it's packaging EPS. I have to admit I haven't seen insulation EPS up close (from less than a few metres away) so I don't know how much different it is: if my experiment had been at all conclusive that'd have been the next question.
Posted By: fostertomHow dya mean 'in the block' - do you mean in the bag? Why should air in the bag show any pressure change (as air is sucked from the bag?) when the bag is extremely free to deflate to equilibriate pressures?Yes, the block originally fitted round the end of a computer or something and the pressure sensor was inside that, surrounded by the plastic. Bit difficult to see in the photo as it's white on white but it's on the centre strut between the two holes in the EPS. I expected the bag to give at least some resistance to any inflow of air so to see some pressure drop if air was being sucked through the EPS.
Posted By: fostertomstraight-through air passage
Posted By: gravelldThere's no problem seen in redundancy (of air tightness) is there
Posted By: fostertomI was thinking that if the foam gun is pushed ALL the way to the back of each joint between EPS sheets then the foam would seal round each sheet to the wall, so stop air movements behind the sheets of EPS.Exactly - and all the fixing cement kept well away from block edges so no danger of it squishing into the joint.
Posted By: gyrogearAlso, on a different note, per the refrenced link, "I have recently been air leakage testing several houses that have been externally insulated for a local council. I'm afraid that 100mm of external EPS insulation has a negligible effect upon the airtightness of a property."
Posted By: Peter_in_HungaryUnless new tests are done after every individual remedial action you will never know what action made the (greatest) difference.
Posted By: djhbuild myself an airtightness testing fanYeah! anyone know of a set of instructions/sources etc?
Posted By: Peter_in_HungaryUnless the air leak test was done before the application of the EWI and again afterwards - with nothing else done at the same time then it is impossible to attribute any change as being due to the EWI. Unless new tests are done after every individual remedial action you will never know what action made the (greatest) difference.
Posted By: ringiWhy not use fixing foam to glue the EPS to the brickwork?You might need an awful lot of it, and you'd be on your own as far as suitability/durability etc. The system suppliers provide cementitious stuff and you use tons of it.
Posted By: fostertomOften repeated and discussed on BuildHub.Posted By: djhbuild myself an airtightness testing fanYeah! anyone know of a set of instructions/sources etc?
Posted By: Peter_in_HungaryPretty sure this is what Paul Jennings would suggest and *probably* has experience of
Unless the air leak test was done before the application of the EWI and again afterwards - with nothing else done at the same time then it is impossible to attribute any change as being due to the EWI. Unless new tests are done after every individual remedial action you will never know what action made the (greatest) difference.
Posted By: djhSorry, so I understand, where's the conventional thinking here? I thought convention was not to bother with any of this, throw some blocks up and collect the ECO grant.Posted By: gravelldThere's no problem seen in redundancy (of air tightness) is there
No but neither is there any value in conventional thinking. There's no way to test multiple layers and its very easy to make mistakes by sloppy thinking or sloppy workmanship. Having said that, for my small bits of timber-framed wall and for my roof, I have a membrane backed up by warmcel, which may give me some free reliability but nobody will ever know.
Posted By: gravelldPosted By: fostertomOften repeated and discussed on BuildHub.Posted By: djhbuild myself an airtightness testing fanYeah! anyone know of a set of instructions/sources etc?
