Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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.

Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




    • CommentAuthorluz13827
    • CommentTimeJan 4th 2022
     
    We have a UPVC bay window in our Victorian property, which we'd ideally like to keep/improve rather than entirely replacing (due to environmental impact, and cost). We previously noticed some mould around some of the corner areas - we know that one of the panes of glass had a blown seal (which we will replace), so this was likely a contributing factor. However we want to ensure that the window frames themselves are well fitted, so as to avoid any major cold bridging.

    Is there anything retrospective that we can do to check for this/improve e.g. should the window frames be removed and refitted, ensuring any gaps are well sealed? Or is it a case that if we can't see any gaps, then aside from the blown seal on the glass, we shouldn't need to do much?

    Also, the walls on the bottom and sides of the window as masonry, which we have added insulating lime plaster to. However, above the window is laths - not sure what to do with those - just cover with lime plaster?
    • CommentAuthorRobL
    • CommentTimeJan 4th 2022
     
    Often upvc windows are screwed in by the sides, sometimes top, siliconed outside, and a bit of upvc trim or silicone on the inside to tidy it up. What I've done with ones like this, is remove the trim/silicone inside to find 10mm gaps - spray a bit of water in gaps and expanding foam, then make good after. I've also drilled holes in inconspicuous parts of the upvc extrusions, and filled them with expanding foam too - you shouldn't do this with any parts that might have water dripping through them to the drains at the bottom. I think you could do upright sections (not below an opening window), and top sections of upvc extrusions. Generally done by removing the glass, drilling 7mm holes every 30cm or so, carefully putting in expanding foam, and something to stop it going everywhere which it will find a way of doing ..
    You may find significant metalwork for strength in the corner mullions, so won't usefully be able to insulate these further.
    I wouldn't bother removing and refitting unless you want to change the position?

    Nb: warm edge glass, planitherm total+ or somesuch softcoat, defn. not aluminium spacers. It's the U value of the glass that makes most of the difference between windows, not the frames.
    • CommentAuthorgravelld
    • CommentTimeJan 4th 2022 edited
     
    Posted By: luz13827We previously noticed some mould around some of the corner areas
    It might depend a bit on which corners you mean - e.g. the junction with the wall, the ceiling, or between two frames (that make up the angle of the bay). A photo might help.
    • CommentAuthorluz13827
    • CommentTimeJan 6th 2022 edited
     
    Thanks - for example like this (additional pic to follow). Please note that we have stripped this all back, used insulating lime render on this wall below the window (and also improving general ventilation and heating in the property). But I just want to ensure the windows themselves aren't contributing to the thermal bridging more than necessary. Not aiming for passivhaus or anything, just want to ensure no mould
      b - INSIDE - mould below window sill on external wall.png
    • CommentAuthorluz13827
    • CommentTimeJan 6th 2022
     
    And here
      d - INSIDE - mould on external wall, below window sill.png
    • CommentAuthorluz13827
    • CommentTimeJan 6th 2022
     
    @RobL thank you - that's useful info, we will share with our builders to see if they can help do that
  1.  
    Posted By: RobLOften upvc windows are screwed in by the sides, sometimes top, siliconed outside, and a bit of upvc trim or silicone on the inside to tidy it up. What I've done with ones like this, is remove the trim/silicone inside to find 10mm gaps - spray a bit of water in gaps and expanding foam, then make good after. I've also drilled holes in inconspicuous parts of the upvc extrusions, and filled them with expanding foam too - you shouldn't do this with any parts that might have water dripping through them to the drains at the bottom.

    If you do fill in the gaps around the frame be sure to support the frame on the inside of opening lights (battens with wedges gently banged in) to stop the foam distorting the frame as it expands and so jamming the window on opening and closing.
    • CommentAuthorgravelld
    • CommentTimeJan 6th 2022 edited
     
    I'm glad I asked for photos because I completely misinterpreted your original question!

    The fact that mould is showing all over the wall suggests the wall as a whole is still going to be a problem. Granted there is worse mould at the junction between two walls and the window (the former of which you'd expect as geometric thermal bridging).

    It's difficult to see what you can do short of heating and ventilating more, or making some fairly large interventions. I'm guessing this is a single skin wall.

    You could hire/borrow a thermal imaging camera to check if there are any obvious weak spots.

    Is the wall lined with paper? On your second picture, there's no gap between the wall and the bottom of the window board is there? I assume it's wet plastered, not boarded.

    The bay window (the construction, not the window frames and glazing) is original and not added later, correct?

    I suppose you could refit the window board with something more insulating but I doubt that's going to make a huge impact and I think you'll be chasing the problem. I was wondering if the telephone points were a clue with some dodgy holes from wiring, but that might be grasping at possibilities.

    Long term I suspect you either need to heat and ventilate more, or insulate the wall.
    •  
      CommentAuthordjh
    • CommentTimeJan 6th 2022
     
    Posted By: gravelldI was wondering if the telephone points were a clue with some dodgy holes from wiring, but that might be grasping at possibilities.
    Looking at the photos that seems like a possibility that's worth investigating. Where do all the wires from those boxes go?

    I wonder if there's some convection up from the radiator to be cooled a bit by the window then across to the other window where it falls down being cooled some more and then back along the wall where there's mould to the radiator? Maybe it would be worth an experiment of a plank or even a piece of cardboard up the side of the radiator to stop any direct convection. A radiator shelf or an extension of the window board might be an alternative.
    • CommentAuthorgravelld
    • CommentTimeJan 10th 2022
     
    One thing I forgot to mention - the wall isn't damp is it? Could there be higher humidity in the wall, for whatever reason which is exacerbating the mould problem by keeping abs humidity high and also the temperature low?
    • CommentAuthorluz13827
    • CommentTimeJan 11th 2022
     
    Thanks all - interesting idea about the radiator convection - hadn't though of that!

    We have since stripped the wall back, and plastered it with insulating lime/cork plaster, and will have a vapour permeable finish now. So I am hoping that helps. We are also improving heating and ventilation in the whole property. So if it's largely down to that, I am OK. Was just trying to rule out anything else that we should be considering, while renovating. We are debating whether to replace the windows still, just to ensure they are efficiently performing. We aren't sure when these ones were put in (the bay window itself is original, but the current frames/glazing we aren't sure how old they are).

    Will make sure we check for any of the holes for wires too.
    • CommentAuthorRobL
    • CommentTimeJan 11th 2022
     
    Can you take a pic of the upvc window itself? Open the shutters and take a pic - they are just internal shutters we can see, is that right, or am i confused?
    Standard Double glaze units used to be U=2.7, they’re mostly 1 to 1.4W/m2/degC now, as of maybe 15years ago. Frames haven’t improved much in contrast.
    If you have an IR temp sensor you can calculate the U value of the glass.
Add your comments

    Username Password
  • Format comments as
 
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press