Tetrarch Posted March 2 Share Posted March 2 Hi, Our Arhictect/Designer has specified 90mm Kingspan K-106 in the cavities of our new walls. This brings the U-value to 0.17 I've ordered the insulation. Do I need special tape for these boards or is there a high-performance tape that is recommended, or is tape just tape? Regards Tet Link to comment Share on other sites More sharing options...
Iceverge Posted March 2 Share Posted March 2 Is it too late to bump the cavities to 200mm and use mineral wool batts or EPS beads? Link to comment Share on other sites More sharing options...
Tetrarch Posted March 2 Author Share Posted March 2 18 minutes ago, Iceverge said: Is it too late to bump the cavities to 200mm and use mineral wool batts or EPS beads? Yep - too late Tet Link to comment Share on other sites More sharing options...
Iceverge Posted March 2 Share Posted March 2 How about full fill cavities and an insulated internal service cavities. Its very hard get a good result with boards in the cavity. Link to comment Share on other sites More sharing options...
Brickie Posted March 2 Share Posted March 2 4 minutes ago, Iceverge said: How about full fill cavities and an insulated internal service cavities. Its very hard get a good result with boards in the cavity. +1 to that. Link to comment Share on other sites More sharing options...
Iceverge Posted March 2 Share Posted March 2 Kingspan have a way of being, well, suspect with the declaration of their products performance. https://www.bbc.com/news/uk-northern-ireland-55986486 To get 0.17W/m2K from your build up your house would need to be constructed in a laboratory with zero wind ever, They count all kinds of things like insulating plaster and theoretical but imaginary stationary air external to the boards. A really excellent install might get you to about 0.21W/m2K. In reality I would plan on something mid 0.20''s to 0.30's for your heat loss calcs. Also ask the architect how much of a back hander Kingspan gave them. Link to comment Share on other sites More sharing options...
MikeGrahamT21 Posted March 2 Share Posted March 2 (edited) Self adhesive breathable tape it specifies https://www.builderdepot.co.uk/wraptite-tape-100mm-x-50m?gad_source=1&gclid=CjwKCAiAuYuvBhApEiwAzq_YifAiLwSC0NIFRUl0LYEG73Uatlf9z2-oWwS69VZb36WkUZUMfK38ixoCmOgQAvD_BwE That type stuff should be ideal, minimum 100mm wide. it seems to be their preferred product https://www.insulationshop.co/image/catalog/pdf/Kingspan/Kingspan_Kooltherm_K106.pdf Edited March 2 by MikeGrahamT21 1 Link to comment Share on other sites More sharing options...
Iceverge Posted March 2 Share Posted March 2 (edited) Sorry if that's hasn't helped you. Lazy architects speccing a difficult to build house with very expensive insulants from a company who continue to be lax with the truth hit a nerve with me. My number 1 advice. 1. Send the insulation back. Widen the cavity to 200mm and use EPS beads or Mineral wool batts. 2. If you can't widen the walls change build methods to something more lightly to perform well in real life. For example: 100mm brick 35mm cavity 60mm PIR 11MM OSB tapes as airtight layer 95*44mm studs @400cc with mineral wool insulation. 12.5mm plasterboard and skim. A realistic U value of 0.21. for the same width of wall with excellent thermal bridging characteristics and airtightness prospects. 3. Get really really fastidious installing the Kooktherm boards. 1. Build the inner leaf to lead the external by 3 courses. Very carefully scrape and brush away any mortar so you can pin the boards tightly to the inner leaf and each other. All cutting will need to be done accurately too. Use a jig or a table saw. 2. Foam the perimeter of each board in a continuous bead as well as and "X across the middle before pressing it home to the inner leaf. This is to prevent any air movement behind the boards that will render it ineffective. Similar to how this EWI job is being done https://youtu.be/i98oKu5EGH4?si=Lf3SsdtxpO2h_MeO 3. Use low expansion foam with a long life span to join all boards and seal tightly around the penetrations allow the foam to mushroom out between joints. When it dries carefully trim it back and tape with a foil backed tape. This will obviously need to be done in dry weather. 4. Ensure that that any exposed cuts ( like at the corners) are sealed with foil tape at the edges to reduce gas migration from he boards over time reducing their insulative effects. This won't be don't by brick layers as they work in a market where sadly almost all clients are uninterested in real world performance. You'll probably need to be on site yourself if you want this level of attention to detail. Edited March 2 by Iceverge Link to comment Share on other sites More sharing options...
TonyT Posted March 2 Share Posted March 2 Can you not oversheet the timber frame with another layer of board? Link to comment Share on other sites More sharing options...
Tetrarch Posted March 3 Author Share Posted March 3 10 hours ago, TonyT said: Can you not oversheet the timber frame with another layer of board? There is no timber frame. This is for blockwork and a mahoosive 6.5m opening with two goalpost steels, one for support, the other to hang the doors from. I'm trying to keep the corner block as narrow as possible (328mm) hence the K-106. There's only 15m of walls and 7.5m of glass (all triple glazed) Regards Tet Link to comment Share on other sites More sharing options...
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