gravelrash Posted July 12, 2022 Share Posted July 12, 2022 Well on with my build which is masonry block wall with warm flat roof...but i have issue with the airtightness of walls and roof as the roofer seemed to take umbrage with me telling him how I wanted it doing and I could not be there all the time to check. I can not get wet plaster as all the old boys have gone and the younger guys are pricing to avoid (although some have said nobody has the skill nowadays) so will be going dry lining route. Walls are thomas Armstrong ultralites, I have parged them with cement slurry and soudal lq around sockets, cable chases and floor to wall junction but wondering if I should give it a second slurry coat? although the plasterers have all said a waste of time and they will just fully adhere around board edges and socket and cable runs. Any input/advice gratefully received. Regarding ceiling void, I have used a double layer of butyl around joists and used soudal SWS foam along edges of osb roof deck to wall connection- I recently had EPS bead blown in cavity and checked connection for leakage while air pressure was high in cavity with no leakage apparent, but not 100% happy that the OSB deck would be fully airtight although it has bitumen vcl above... I am thinking I should make the ceiling plasterboard a secondary airtight layer if possible. Again any advice would be helpful. Q. anybody know where I can get airtight tape for plaster boards? as I need to seal ceiling boards to partition walls and seal all joints. Link to comment Share on other sites More sharing options...
nod Posted July 12, 2022 Share Posted July 12, 2022 As I’ve said on so many occasions on here Parge is a waste of time for airtightness Although as a business I use hundreds of bags per year and always refer to it as sound coat As it will encourage the dry liners not to seal everything up properly If they think it has already been done Our previous build Block and brick achieved 2. Something on an air test It would have been better if we hadn’t been forced to install sash windows About 30% of my business is wet plaster still But expect to pay about 40% more in laboure and 12.5 less on the materials If you make sure the dry liners acoustic seal the perimeter of ALL ceilings and a picture frame continuous line to all internal angles and solid around switches and sockets You will achieve good results But be clear this is what you expect As it will be pretty obvious when the walls start to dry out Link to comment Share on other sites More sharing options...
Iceverge Posted July 12, 2022 Share Posted July 12, 2022 DIY blower fan. We tested 0.31ach after only a scratch coat of sand cement plaster. Most of the gaps I found were the backs of wall chases and around windows. 1 Link to comment Share on other sites More sharing options...
gravelrash Posted July 12, 2022 Author Share Posted July 12, 2022 1 hour ago, Iceverge said: DIY blower fan. We tested 0.31ach after only a scratch coat of sand cement plaster. Most of the gaps I found were the backs of wall chases and around windows. thats pretty impressive...how did you diy test? Link to comment Share on other sites More sharing options...
MikeSharp01 Posted July 12, 2022 Share Posted July 12, 2022 1 hour ago, Iceverge said: 0.31ach Is that the Passive house measure at 50% of minimum requirement - that's attention to detail. 1 Link to comment Share on other sites More sharing options...
Iceverge Posted July 12, 2022 Share Posted July 12, 2022 3 hours ago, gravelrash said: thats pretty impressive...how did you diy test? No, I paid for an official test. A very thorough German came and did it. 1 Link to comment Share on other sites More sharing options...
George Posted July 14, 2022 Share Posted July 14, 2022 I was told that even a layer of paint will help seal the blocks and mortar. not sure how true it is but I did put some on before the plasterboard went up. However as it was an extension it didn't really matter compared to the rest of the leaky house. Link to comment Share on other sites More sharing options...
gravelrash Posted July 15, 2022 Author Share Posted July 15, 2022 bump Link to comment Share on other sites More sharing options...
Carrerahill Posted July 15, 2022 Share Posted July 15, 2022 On 12/07/2022 at 13:41, gravelrash said: I can not get wet plaster as all the old boys have gone and the younger guys are pricing to avoid (although some have said nobody has the skill nowadays) so will be going dry lining route. You cannot get someone to plaster a block wall? As in a bog standard, interior block wall? Link to comment Share on other sites More sharing options...
gravelrash Posted July 15, 2022 Author Share Posted July 15, 2022 I know it is hard to believe. Plasterers are probably just looking for the easiest cash just as most of the trades are ( at highly inflated rates). three were just very open about there skill levels and did I want it flat and level, then best have dot and dab! Link to comment Share on other sites More sharing options...
JohnMo Posted July 16, 2022 Share Posted July 16, 2022 Why not just have a diagnostic air test done, before you proceed any further. That will tell you if you are ok or not. You only need the house depressed walk around and the back of your hand will indicate where leaks are. Link to comment Share on other sites More sharing options...
gravelrash Posted July 16, 2022 Author Share Posted July 16, 2022 5 hours ago, JohnMo said: Why not just have a diagnostic air test done, before you proceed any further. That will tell you if you are ok or not. You only need the house depressed walk around and the back of your hand will indicate where leaks are. still waiting for windows but once fitted was wondering if the mhvr unit would be an easy way to suck the air out if I block the inlet...would it achieve sufficient depressurisation? Link to comment Share on other sites More sharing options...
JohnMo Posted July 16, 2022 Share Posted July 16, 2022 Would doubt the fans man enough. Plus you don't want it running until all the inside is sealed up. 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 16, 2022 Share Posted July 16, 2022 1 hour ago, JohnMo said: Would doubt the fans man enough. Plus you don't want it running until all the inside is sealed up. You also wont want to suck all the build dust into it either. 200w or less fan size will do very little. You should seal u the MVHR ducts when you depressurise, if you've connected to atmosphere? Link to comment Share on other sites More sharing options...
dpmiller Posted July 16, 2022 Share Posted July 16, 2022 17 minutes ago, Nickfromwales said: You also wont want to suck all the build dust into it either. 200w or less fan size will do very little. You should seal u the MVHR ducts when you depressurise, if you've connected to atmosphere? how many watts do you think a car electric fan is? Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 16, 2022 Share Posted July 16, 2022 (edited) 1 hour ago, dpmiller said: how many watts do you think a car electric fan is? According to my basic maths, 800w and upward. They’re far more aggressive than a typical MVHR fan. So, around 3-4x the power or more. Edited July 16, 2022 by Nickfromwales Link to comment Share on other sites More sharing options...
Mr Punter Posted July 16, 2022 Share Posted July 16, 2022 3 hours ago, gravelrash said: still waiting for windows but once fitted was wondering if the mhvr unit would be an easy way to suck the air out if I block the inlet...would it achieve sufficient depressurisation? Err no. When they do the air test they mount a bfo fan, normally in the front door opening. It will be good for over 500l/s compared to a bathroom extract at about 20l/s. A big MVHR unit will manage 175l/s but most are less than 100l/s. 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 16, 2022 Share Posted July 16, 2022 +1 Link to comment Share on other sites More sharing options...
dpmiller Posted July 16, 2022 Share Posted July 16, 2022 2 hours ago, Nickfromwales said: According to my basic maths, 800w and upward. They’re far more aggressive than a typical MVHR fan. So, around 3-4x the power or more. Dunno what kind of cars youve been looking at but that aint accurate in my experience- that's 65A you're talking. Cite a source? No, a more resonable guess would be right at the 200w mark, and often much less eg from Spal, a well-known manufacturer to OE and Motorsport https://www.ebay.co.uk/itm/201955247521 Link to comment Share on other sites More sharing options...
Iceverge Posted July 16, 2022 Share Posted July 16, 2022 Had a gander out of interest. A BMW 740 is 580w. Most cars probably about half that. One for an Insignia 2.0d online for £20 at the moment. Just make sure you get the plug with some wire from the scrappy too as the OEM sockets in the housing can be a pig to get into Link to comment Share on other sites More sharing options...
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