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Closing a 200mm cavity with ply.

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Comments

  • #32
    cork2
    Registered Users Posts: 291 ✭✭cork2


    miller_63 wrote: »
    First off I didn't ask for your advise. I offered first hand real world evidence for a solution the OP asked for help with. I have already been advised by some of this countries top consultants so if that offends you and makes it read for 'smart assed' I'm not really going to lose any sleep over it.

    Secondly if you can't provide real world evidence to your claims and or theory then its all a moot point is it not? You are adamant and shouting hellfire and brimstone re delaminating ply. All I have asked you to do is provide first hand evidence of this. Show us your detail, the install and the results and then I will take the issue up in more detail.

    If you have competent consultants advice then ok, brilliant I'll stop arguing. Just make sure you have it on paper.

    As for plywood, I am shouting and I'll keep shouting. Plywood is rubbish FACT. I have no intention of going to the trouble of getting pictures from the computers at work to show you delaminating ply wood. If you're currently involved in construction is this country you'll know only too well that this is a major issue as pointed out also by other posters. I'm not against you're whole detail just the Plywood. If you could use cement board or PIR or something I wouldn't have much against. It's logical Cavities are are damp and not ventilated please tell me why you think this is a good combination for wood?? Manmade wood product at that!!

    Now I admit last night I shouldn't have called you smart assed or cocky. The OP asked a question and you gave your opinion. I've also given mine, we don't agree on the subject and I don't believe we will therefore I've argued long enough. Timber does not belong in cavities and putting it there is an unnecessary risk, we cover the roof timber to keep it dry and paint paint the front door for the same reason. This is my opinion and nothing else. As far as I'm concerned I won't be posting on this thread again or we'll start going around in circles. Best of luck whatever way you decide to go OP!!


  • #33
    cork2
    Registered Users Posts: 291 ✭✭cork2


    hexosan wrote: »
    I think one of the issues Miller has is that on this site if you look for an opinion your slated for not engaging a professional, then when you do engage one your still slated

    There's no harm in discussion and debate but once you have the options and the info a professional opinion is key!!! You don't know any of us are, don't take the risk!!


  • #34
    dfader
    Registered Users Posts: 120 ✭✭dfader


    miller_63 wrote: »
    Overkill? Maybe in your book.....

    Yes, in my book....if you interested here is one of the books I read, which lead me to make that comment; http://www.greenbuildingstore.co.uk/page--denby-dale-passivhaus-technical-film.html
    Theres a technical briefing you can get for this house - you have to apply and they will send you a copy.

    The attached detail with which also has an image of the Isotherms through the junction also influenced my comment.

    Interesting debate hearing the comments from those with experience about the quality of plywood products these days and the possible delaminating.


  • #35
    lownhard
    Registered Users Posts: 167 ✭✭lownhard


    Hi

    My builder has used this plywood onsite. It is supposed to be marine ply. Is this marine ply? Seems rubbish.

    http://www.img.ie/image/Zu2

    http://www.img.ie/image/ZuM

    http://www.img.ie/image/Zu6


  • #36
    cork2
    Registered Users Posts: 291 ✭✭cork2


    It would worry me that the writing on the tag is Chinese or something along those lines. From a picture to me that doesn't look like marine it looks like the stuff they're calling WBP these days. I can't say for sure whether it's high quality or low quality but it has a CE stamp on it. What is it being used for?


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  • #37
    galwaytt
    Registered Users Posts: 12,751 ✭✭✭✭galwaytt


    lownhard wrote: »
    Hi

    My builder has used this plywood onsite. It is supposed to be marine ply. Is this marine ply? Seems rubbish.

    http://www.img.ie/image/Zu2

    http://www.img.ie/image/ZuM

    http://www.img.ie/image/Zu6
    cork2 wrote: »
    It would worry me that the writing on the tag is Chinese or something along those lines. From a picture to me that doesn't look like marine it looks like the stuff they're calling WBP these days. I can't say for sure whether it's high quality or low quality but it has a CE stamp on it. What is it being used for?

    Hard to say for sure: the label, frankly, could be printed by anyone - you'd actually have to see the certificate and see who was the notified body - there is nothing on that label about who certified it........ A brother of mine has worked for several notified bodies (UK, Netherlands, Germany), including visits to China, and tbh what he described would scare the bejasus out of you (and not in a wood industry capacity) - he actually refused to CE pass the factory in question..........

    What worries me about your sample is the cross section. If you bear in mind you should have a single piece middle layer, why are there pieces or a void............see my photo from China for a possible reason. If your ply is just a good top & bottom veneer, but junk in the middle (offcuts, bark, bulked up with glue/sawdust), then it's only good for firewood.........

    Nothing to stop you taking that piece of ply and taking it apart - now is the time to do it, not after it's up on the house.....

    Btw, please tell me that the expanded corner bead in the pic is NOT because your plastering the ply.................



    P.S. I've heard anecdotally certain people referring to CE in this context meaning 'China Export'..............

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



  • #38
    rampantbunny
    Registered Users Posts: 907 ✭✭✭rampantbunny


    Interesting thread. Moreso because I've a 200mm cavity, and have used marine ply to close the window and door reveals, behind which I friction fitted 100mm thick PIR board.

    Before installing the ply I left some exposed to bad weather conditions at the start of the year. Some snow, frost, rain, drying out. Not just a week, but over 2 months.
    Before fitting of windows, ply was in place (uncovered) for probably another month. It got wet, dry, wet again.
    I could see no delamination.

    Windows went in, and 2 months later, ply is uncovered internally in an unpumped cavity, therefore I imagine it is pretty dry. After windows were fitted, on outside I used good quality sealant to stick the vertical DPC to window frame where it overlapped. Subsequently plastered over this. Next task will be to clean where the plaster meets the window and apply another bead of sealant.

    Will the ply deteriorate in the cavity - my understanding from the above posts is that it will because there is no ventilation.
    I didn't think cavities were airtight...there is some air albeit maybe not enough to call ventilation. But don't I have to worry about the ply getting wet again and being unventilated before it becomes a concern.


  • #39
    Ares Proud Production
    Closed Accounts Posts: 1,011 ✭✭✭ Ares Proud Production


    The pictures posted above are of stock Ply above are not Marine Grade Plywood AFAIK.

    I have gone to the expense of Marine Grade Ply and not anything ordinary or cheap. I have since spoken with our plasterer, between us all we can see is one place for 'potential' water ingress. Now the water ingress level required to delaminate Marine Grade ply is an awful lot and in my instance will not happen bar a catastrophic event. All down to detailing and best practice install.

    (a catastrophic event would harm all jamb details let alone a ply reveal)

    Our only view on water/damp ingress into the cavity is between the Render seal to the frame. In our case we have quite a bit of frame hidden here so made sense to put in a waterproof mastic sealant here between the Unit and the rear of the DPM. On top of this the Render (which has its own waterproofer mixed in) provides the preliminary barrier to prevent water penetration as it is tight up against the window. Beyond this the mastic sealant provides a secondary barrier.

    Beyond this there are no other areas for water ingress.

    @cork2 Thank you for the clarity and the retraction of those comments. Debate is good and maybe we all get a bit heated, i know I do as im under pressure with the whole job etc etc. Anyways reiterating the comments earlier when I asked for evidence of Plywood delaminating in cavity in this detail, reading back this still hasn't been produced. Its okay to talk about stock ply delaminating when left exposed. We all know that happens and we agree with you that stock ply doesn't belong anywhere near the cavity, especially any cheap grade ply like you have shown. But in this instance is decent marine grade ply really going to suffer like you say? I would be interested to know which project you pulled the delaminated marine grade ply out of the cavities, and if possible id like a chat with the owner to see what he/she would have done different? Pictures of before and after would be interesting of this install you refer to.


  • #40
    galwaytt
    Registered Users Posts: 12,751 ✭✭✭✭galwaytt


    miller_63 wrote: »
    The pictures posted above are of stock Ply above are not Marine Grade Plywood AFAIK.

    I have gone to the expense of Marine Grade Ply and not anything ordinary or cheap. .

    May I ask how you know that the ply you used is actually marine spec? (genuinely curious)

    The issue that the industry has atmo is that a no of the markings and supporting paperwork is of dubious origin. Traceably certified ply is fine if that's what you actually get, but it is in the minority in supply.

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



  • #41
    Ares Proud Production
    Closed Accounts Posts: 1,011 ✭✭✭ Ares Proud Production


    galwaytt wrote: »
    May I ask how you know that the ply you used is actually marine spec? (genuinely curious)

    The issue that the industry has atmo is that a no of the markings and supporting paperwork is of dubious origin. Traceably certified ply is fine if that's what you actually get, but it is in the minority in supply.


    Its stamped, its traceable and the assurance of one of the leading suppliers in the country.

    This is not a 'done deal' or 'adverts' built house BTW

    Do you want me to video a boil test on it?


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  • #42
    cork2
    Registered Users Posts: 291 ✭✭cork2


    miller_63 wrote: »
    Its stamped, its traceable and the assurance of one of the leading suppliers in the country.

    This is not a 'done deal' or 'adverts' built house BTW

    Do you want me to video a boil test on it?

    You're not grasping the seriousness of the plywood issue. The leading suppliers in the country are stocking the rubbish!! One nationwide timber importer is selling it and the largest builders providers in munster, they're selling it as marine and as WBP!! You don't need to be doing a "donedeal house" to get caught.
    I don't need to see a boil test it makes no difference to me either way. I'm not try prove anything I'm simply pointing out that a major issue exists if you're happy you managed to get the real deal then you are one of the lucky ones.


  • #43
    Ares Proud Production
    Closed Accounts Posts: 1,011 ✭✭✭ Ares Proud Production


    cork2 wrote: »
    You're not grasping the seriousness of the plywood issue. The leading suppliers in the country are stocking the rubbish!! One nationwide timber importer is selling it and the largest builders providers in munster, they're selling it as marine and as WBP!! You don't need to be doing a "donedeal house" to get caught.
    I don't need to see a boil test it makes no difference to me either way. I'm not try prove anything I'm simply pointing out that a major issue exists if you're happy you managed to get the real deal then you are one of the lucky ones.

    You're not reading the responses or considering the detail in greater depth, all you can see is the word 'ply' and immediately start the same spiel again and again..

    That's fine, I do grasp the seriousness but the more I tell you the Marine Ply I have on site is fine the more you keep coming back 'stocking rubbish' and delamination within cavities. Its not a general comment its become specific and personally directed. So the more I want to see proof to back up your claims.

    I do agree with the major issue and that it needs highlighting as I guess so many other people would be unaware on how to check/tell. One sure fire way to tell how genuine a ply board is the price. I know I could have bought a cheaper alternative and therein lies the problem.

    The problem here is you are swinging the tar brush at everyone and dismissing everything else as wrong.


  • #44
    rampantbunny
    Registered Users Posts: 907 ✭✭✭rampantbunny


    miller_63 wrote: »
    One sure fire way to tell how genuine a ply board is the price. I know I could have bought a cheaper alternative and therein lies the problem.

    To be fair Miller_63, that won't qualify as a sure fire way in this fair country of ours. It would suggest that paying a high price always guarantees the best product.

    Cork2...on the other side, and I'm not mediating here, how damp is the cavity going to get in reality if the detail miller has described is executed correctly?


  • #45
    galwaytt
    Registered Users Posts: 12,751 ✭✭✭✭galwaytt


    miller_63 wrote: »
    ... One sure fire way to tell how genuine a ply board is the price. I know I could have bought a cheaper alternative and therein lies the problem..

    ...you were doing OK until you said ^^^^

    There is no warranted correlation between price and the quality.

    There is price, and there is quality. Two different subjects. One is variable, one is objective.

    As cork2 says, you can buy the ply wherever you want, but many reputable suppliers have been caught out too.

    There is a very large qty of so-so plywood sitting in the likes of Rotterdam looking for a 'home', and so caveat emptor. I had a seller in to me yesterday offering me ply, WPB and OSB in any quality and size including (and I quote) "shyte from China". When I asked if people are still buying it he told me that there's a market for resale for those who are only interested in the price.

    So, you can do a boil test if it makes you feel better- at least you know what that is: think of all the others who don't, or shouldn't need to tbh.

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



  • #46
    cork2
    Registered Users Posts: 291 ✭✭cork2


    Ares Proud Production wrote: »
    You're not reading the responses or considering the detail in greater depth, all you can see is the word 'ply' and immediately start the same spiel again and again..

    That's fine, I do grasp the seriousness but the more I tell you the Marine Ply I have on site is fine the more you keep coming back 'stocking rubbish' and delamination within cavities. Its not a general comment its become specific and personally directed. So the more I want to see proof to back up your claims.

    I do agree with the major issue and that it needs highlighting as I guess so many other people would be unaware on how to check/tell. One sure fire way to tell how genuine a ply board is the price. I know I could have bought a cheaper alternative and therein lies the problem.

    The problem here is you are swinging the tar brush at everyone and dismissing everything else as wrong.

    You're 110% right, all I'm seeing is the word "ply" and instantly I think "problem". It's a problem with may never arise but why risk it when your detail is perfect using a purpose made insulated cavity closer. As for swinging the tar brush you're right again, simply because I'm at the point where I don't trust ply. Get it from any stockist you like at two hundred euro a sheet and I wouldn't put it anywhere in a house that it can't be easily removed. Also this isn't personally directed. Look we're not getting anywhere, this argument is ridiculous. We don't agree and we won't.


  • #47
    893bet
    Registered Users Posts: 8,727 ✭✭✭893bet


    What are the insulated cavity closers you mention?

    The only one I could find was Kingspan and when I handled the product I found them to be flimsy and very expensive. I have 150mm cavity and closed with PIR cut to fit tightly.


  • #48
    cork2
    Registered Users Posts: 291 ✭✭cork2


    893bet wrote: »
    What are the insulated cavity closers you mention?

    The only one I could find was Kingspan and when I handled the product I found them to be flimsy and very expensive. I have 150mm cavity and closed with PIR cut to fit tightly.

    I too would use PIR, but yes it's the expensive kingspan and other brands are what I was talking about. They seem to be what the majority of Architects and Engineers I'm dealing with are specifying. A plastic profile with a strip of 25mm PIR slipped into them and you build them into the blockwork and them tape the windows onto them. They're only flimsy until they're in place.


  • #49
    sydthebeat
    Subscribers Posts: 40,953 ✭✭✭✭sydthebeat


    havent seen those cavity closers in anything over 150mm cavity widths.


    in this whole thread, has anyone asked what the function of the ply box system is?
    if its just to close the cavity, the PIR would be a much better choice.
    if its to provide structural stability to the windows, have engineers passed this?


  • #50
    rampantbunny
    Registered Users Posts: 907 ✭✭✭rampantbunny


    sydthebeat wrote: »
    havent seen those cavity closers in anything over 150mm cavity widths.


    in this whole thread, has anyone asked what the function of the ply box system is?
    if its just to close the cavity, the PIR would be a much better choice.
    if its to provide structural stability to the windows, have engineers passed this?


    Marine ply in mine is to close the cavity (with PIR directly behind), but to also support the windows. They are 3G inward opening and tilt (tilt/turn) so pretty heavy.
    I have alu angle within the cavity to support the ply. The ply can also be used as part of the airtightness fabric provided the windows are properly taped to it and holes sealed etc. probably easier to run membrane the whole way around the reveal though.

    My engineer was happy for me to build a wall that supported itself in mid air. He saw the detail around the window and wasn't interested either way.
    I'm still looking for floating blocks syd so if you come across any, let me know.


  • #51
    Strolling Bones
    Registered Users Posts: 615 ✭✭✭Strolling Bones


    rampantbunny wrote: »
    I'm still looking for floating blocks syd so if you come across any, let me know.

    I see what you did there :D


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  • #52
    Ares Proud Production
    Closed Accounts Posts: 1,011 ✭✭✭ Ares Proud Production


    cant believe your going ahead with the ply detail, its hell fire and brimstone for you old chap! :eek:

    Im still waiting on my batch of floating blocks and sky hooks.....:D


  • #53
    rampantbunny
    Registered Users Posts: 907 ✭✭✭rampantbunny


    miller_63, you wrote earlier that you have already been advised by some of the countries top consultants. Was your engineer one of these?

    syd, my previous post in answer to yours might have read a bit off. A lot of us are in the same boat re. the ability/interest of our engineers. At this stage, if my engineer said it was OK to do this or that, I'd nearly have reservations.


  • #54
    hexosan
    Registered Users Posts: 1,735 ✭✭✭hexosan


    Right I think I've come up with a solution to prevent water ingress into to cavity at the reveals causing the marine ply to get damp.
    Pro clima do a product called Contega Solido EXO it's an exterior tape used to make the windows wind tight and protect against driving rain. The tape has a 15mm strip that sticks to the frame (gets plastered over) and the remaining 65mm sticks to the blockwork. Tape can then be plastered over with the reveal.


  • #55
    rampantbunny
    Registered Users Posts: 907 ✭✭✭rampantbunny


    I'm thinking that you have to trim your vertical DPC right back to the edge of the blockwork first?

    Is the product water tight?
    I know products can be airtight, but if wet and you touch them from the back, the water can come through..capillary action or something like that.

    [Edit] Just read a prod sheet and it is resistant to driving rain. Does that cover resistence to moisture ingress in damp conditions over a period of time.
    "Adheres to mineral surfaces but with a note that uneven chem. surfaces should be leveled with a smooth finish (if necessary)."

    The mineral surface that is given as an example is concrete, which would usually be smooth. Block-work would probably fall into the category of having to be smoothed out...but if it sticks to begin with I'm sure the plaster coat over it will keep it in place.


  • #56
    hexosan
    Registered Users Posts: 1,735 ✭✭✭hexosan


    I spoke with the suppliers and it's not waterproof it's water resistant. Standing water will penetrate but since it's installed vertically standing water isn't an issue.
    You don't have to cut back the dpc I simply taped over it.
    It sticks to blockwork no problem the adhesive like all the pro clima stuff sticks like **** to a blanket.


  • #57
    The_Bullman
    Registered Users Posts: 1,997 ✭✭✭The_Bullman


    hexosan wrote: »
    Right I think I've come up with a solution to prevent water ingress into to cavity at the reveals causing the marine ply to get damp.
    Was another worry about the ply that it would get damp from the moisture in the cavity?


  • #58
    caddy16
    Registered Users Posts: 684 ✭✭✭caddy16


    893bet wrote: »
    What are the insulated cavity closers you mention?

    The only one I could find was Kingspan and when I handled the product I found them to be flimsy and very expensive. I have 150mm cavity and closed with PIR cut to fit tightly.


    Hi 893bet, I was looking back on old threads and noticed you closed 150mm cavity at openings with PIR. My engineer is recommending the same, did that work out ok for you?

    Did you just apply your airtight tape directly on this after installing windows?


  • #59
    893bet
    Registered Users Posts: 8,727 ✭✭✭893bet


    caddy16 wrote: »
    Hi 893bet, I was looking back on old threads and noticed you closed 150mm cavity at openings with PIR. My engineer is recommending the same, did that work out ok for you?

    Did you just apply your airtight tape directly on this after installing windows?

    Worked fine for me. I had an L block so there was only 50mm PIR at sides if I recall so could use a wide airtight tape (expensive stuff) and a primer. In order to close sill and top to tape i had to use strip of air tight roll (the ceiling one). Tape one side of the strip to the window (normal cheap tape for smooth surfaces) and then the expensive tape again to tape the strip of roll back to the block. Finished with 12mm board. Only had 150 my cavity. You can’t tape to the PIR just to be clear. Window to block is the only option.

    Seemed to work ok. Hope I explained that right.


  • #60
    caddy16
    Registered Users Posts: 684 ✭✭✭caddy16


    893bet wrote: »
    Worked fine for me. I had an L block so there was only 50mm PIR at sides if I recall so could use a wide airtight tape (expensive stuff) and a primer. In order to close sill and top to tape i had to use strip of air tight roll (the ceiling one). Tape one side of the strip to the window (normal cheap tape for smooth surfaces) and then the expensive tape again to tape the strip of roll back to the block. Finished with 12mm board. Only had 150 my cavity. You can’t tape to the PIR just to be clear. Window to block is the only option.

    Seemed to work ok. Hope I explained that right.

    Makes sense, thanks for that.


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