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Passive sills

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  • 14-11-2014 11:42pm
    #1
    Superdaddy
    Registered Users Posts: 234 ✭✭


    Have any of you come across window sills made of high density expanded polystyrene and coated with a polymer resin. I saw them at the City west show in September. Would be interested on your views on these, although twice the price of normal sills they seem to solve a cold bridging problem.


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    #2
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,140 Mod ✭✭✭✭BryanF


    Would you like to share your window cill detail? Perhaps it might help us decide if the polystyrene cill is necessary


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    #3
    Superdaddy
    Registered Users Posts: 234 ✭✭Superdaddy


    100mm block, 150mm full fill cavity, 100mm block, standard sill. Standard detail as per acceptable construction details diagram 5, except with 150 cavity and resting on angle iron attached to outer block instead of resting on inner block.
    Seems to me it would give a much better u value at this detail and eliminate any cold bridge under the window board. I am trying to work out pros and cons.


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    #4
    fclauson
    Registered Users Posts: 1,691 ✭✭✭fclauson


    you will need a tech arch to do an frsi calc to make sure the construction detail complies with Part L


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    #5
    Superdaddy
    Registered Users Posts: 234 ✭✭Superdaddy


    fclauson wrote: »
    you will need a tech arch to do an frsi calc to make sure the construction detail complies with Part L

    Thanks for that, condensation and mould growth are what concerns me with normal concrete sills. My view is that passive sills eliminate the risk completely, am I wrong? Is there something I am missing? I am employing an engineer but I also need to educate myself to know what is going on. That is why I am asking here.


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    #6
    fclauson
    Registered Users Posts: 1,691 ✭✭✭fclauson


    Ok

    you need a tech arch or similar who can model the window cill in its installation to ensure it complies with part L

    Most engineers do no have the skills

    -snip-


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    #7
    galwaytt
    Registered Users Posts: 12,761 ✭✭✭✭galwaytt


    Superdaddy wrote: »
    Thanks for that, condensation and mould growth are what concerns me with normal concrete sills. My view is that passive sills eliminate the risk completely, am I wrong? Is there something I am missing? I am employing an engineer but I also need to educate myself to know what is going on. That is why I am asking here.

    Normal cills should always be insulated inside anyway.

    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” 



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    #8
    Superdaddy
    Registered Users Posts: 234 ✭✭Superdaddy


    galwaytt wrote: »
    Normal cills should always be insulated inside anyway.

    I know what you are saying. Normal cill detail has about 25mm-50mm of insulation on the internal side of the cill. But I'm seeing a cold bridge at the window board junction and a colder spot on the internal wall underneath the window board due to the reduced insulation.
    I will consult my engineer on it, if he doesn't do frsi calcs and there's no structural reason not to use them, I think I will use them. It'll probably cost more than the price difference to concrete cills to get a tech arch to do the calculation for me. Once it's structurally sound and the engineer signs off on it, I can't see a problem with increasing the insulation in this detail. Is there any major pitfall in this approach that I am missing?


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    #9
    galwaytt
    Registered Users Posts: 12,761 ✭✭✭✭galwaytt


    Superdaddy wrote: »
    I know what you are saying. Normal cill detail has about 25mm-50mm of insulation on the internal side of the cill. But I'm seeing a cold bridge at the window board junction and a colder spot on the internal wall underneath the window board due to the reduced insulation.
    I will consult my engineer on it, if he doesn't do frsi calcs and there's no structural reason not to use them, I think I will use them. It'll probably cost more than the price difference to concrete cills to get a tech arch to do the calculation for me. Once it's structurally sound and the engineer signs off on it, I can't see a problem with increasing the insulation in this detail. Is there any major pitfall in this approach that I am missing?

    I must be missing something: the cill is insulated, & if the window frame is a good one and thermally broken, there is no (discernible) bridge if the board meets it anyway.

    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” 



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    #10
    fclauson
    Registered Users Posts: 1,691 ✭✭✭fclauson


    we need pictures to understand please


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    #11
    Superdaddy
    Registered Users Posts: 234 ✭✭Superdaddy


    Please see attached picture courtesy of http://www.josephlittlearchitects.com/sites/josephlittlearchitects.com/files/breaking_the_mould_3_0.pdf

    This is the cold bridge i am referring to, it seem logical to me that if the cill is made from an insulating material it further reduces the cold bridge.


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    #12
    Superdaddy
    Registered Users Posts: 234 ✭✭Superdaddy


    Just knocked this photoshop sketch up to give an idea of the detail I'm thinking about using. I believe a polystyrene cill is far superior at eliminating cold bridging. My question is can ye assist me with the pros and cons of this type of cill?


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    #13
    sydthebeat
    Subscribers Posts: 41,080 ✭✭✭✭sydthebeat


    Joes picture had thermal bridges both in the inner leaf and at the window board.

    careful detailing can avoid these without the use of a more expensive cill.


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    #14
    RITwing
    Banned (with Prison Access) Posts: 246 ✭✭RITwing


    Superdaddy wrote: »
    Just knocked this photoshop sketch up to give an idea of the detail I'm thinking about using. I believe a polystyrene cill is far superior at eliminating cold bridging. My question is can ye assist me with the pros and cons of this type of cill?

    Remind us again how much money you "saved" on working drawings....


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    #15
    Superdaddy
    Registered Users Posts: 234 ✭✭Superdaddy


    RITwing wrote: »
    Remind us again how much money you "saved" on working drawings....

    Would you be another disgruntled architect here to have a pop at the cheeky self builder that thinks he can work it out for himself and do it on the cheap?
    I won't remind you or ye, it seems you remember quite well. I have no regrets.


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    #16
    sydthebeat
    Subscribers Posts: 41,080 ✭✭✭✭sydthebeat


    If you're using this forum as an alternative to professional input then. ...


    I'm out.


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    #17
    893bet
    Registered Users Posts: 8,785 ✭✭✭893bet


    RITwing wrote: »
    Remind us again how much money you "saved" on working drawings....

    such a familiar posting style! Change of name....same old posts.


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    #18
    BryanF
    Moderators, Home & Garden Moderators Posts: 10,140 Mod ✭✭✭✭BryanF


    Directly from the forum chater: This board is intended for discussion of Construction & Planning issues, by fellow users, and as a place to openly exchange tips and advice for free i.e. no one must seek to gain personally, professionally or financially from their participation in the forum . It is not a consultancy service and it is strongly advised that you always appoint your own professional advisor(s). Be aware that being an open public forum you may not always get exactly the response you would hope for. You will find that there are plenty of posters who will help you here but if you don't like some posts or posters try to pass over them back on topic thanks


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    #19
    Superdaddy
    Registered Users Posts: 234 ✭✭Superdaddy


    sydthebeat wrote: »
    If you're using this forum as an alternative to professional input then. ...


    I'm out.
    That is not the case.
    I have an architectural technician to do my drawings and an engineer to design, advise and sign off. I do my own research and I put my findings to them to draw them. I researched my foundations and picked the type that suited, my engineer approved and designed it, i purchased it and hired the builder to install it. I do not have an Architect dictating to me how he wants it done and which of his mates is doing it and charging me a percentage of my mortgage for the pleasure. I cannot afford to do that, I wish I could, I need to work on my house.
    I am compliant with all regulations so far and will be at the end. I will have an A rated home which will be near passive or zero carbon. Its a steep learning curve and it costs me a lot of time.
    There seems to be considerable resentment to self builders here. It wasn't self builders that caused all the problems of the past which required the regulations which have brought self building to an end since March (which i thankfully avoided). A self builder building their family home will put more into it than any self styled unqualified property developer and will have far greater knowledge accumulated.

    All I asked for here was an opinion on a product, not an inquisition or to have a bunch of people looking down their noses and sneering.
    I have learnt a lot from this forum and met some good people but there also seems to be a judgemental crew of professionals intent on battering anybody who doesn't sing to their tune.
    893bet wrote: »
    such a familiar posting style! Change of name....same old posts.
    I thought that too.


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    #20
    bmm
    Registered Users Posts: 912 ✭✭✭bmm


    I'm sure there are lots of nonprofessional people that will help you here. Its quite sad that anyone would act in this way, disgusting in fact.

    Have a look at this link.

    http://constructionstudiesq1.weebly.com/window-cill-head-and-jamb.html


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    #21
    galwaytt
    Registered Users Posts: 12,761 ✭✭✭✭galwaytt


    Superdaddy wrote: »
    Please see attached picture courtesy of http://www.josephlittlearchitects.com/sites/josephlittlearchitects.com/files/breaking_the_mould_3_0.pdf

    https://us.v-cdn.net/6034073/uploads/attachments/205797/329093.jpg

    This is the cold bridge i am referring to, it seem logical to me that if the cill is made from an insulating material it further reduces the cold bridge.

    I've been away all week so just seeing that now. .. That cill detail doesn't match any cill I've ever seen. Never seen the upstand on any cill that size. I think that sketch is wrong.

    And your window board is timber, so that's an insulator anyway.

    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” 



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    #22
    galwaytt
    Registered Users Posts: 12,761 ✭✭✭✭galwaytt


    Superdaddy wrote: »
    Just knocked this photoshop sketch up to give an idea of the detail I'm thinking about using. I believe a polystyrene cill is far superior at eliminating cold bridging. My question is can ye assist me with the pros and cons of this type of cill?

    That's still wrong imho. You are showing a huge thick upstand nib: most I see are shallower than the window frame, you need to work off proper drawings.

    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” 



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    #23
    ht9zni1gs28crp
    Closed Accounts Posts: 1,011 ✭✭✭ht9zni1gs28crp


    Before you go down the line of thinking traditional cill details, just check with your window supplier re them providing an ali cill. It may be more Wonga but it will help.

    Just means you rethink your cavity closer, but a Cill attached to the frame makes the cold bridging a LOT easier to deal with.

    Speaking from experience....


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