Bay windows, cracks, and uPVC

Discussion in 'Builders' Talk' started by jcliv, Feb 3, 2014.

  1. jcliv

    jcliv New Member

    Hello,

    Just moved into a 1930s semi and discovered a number of cracks below and to the sides of an L-shaped window on the ground floor (there is no window above this, only a small tiled pitched roof). I am guessing this may have occurred when the previous owners fitted uPVC windows? However, the windows were fitted 20 years ago, show no signs of warping, and the door opens easily with no sticking. The cracks had been filled. I was hoping to get some opinions on whether the windows are likely to still be causing ongoing deterioration of the wall, and what action needs to be taken to fix the problem?

    Many thanks

    J
    image.jpg image.jpg image.jpg image.jpg image.jpg
  2. Phil the Paver

    Phil the Paver Well-Known Member

    Is there any sign of the cracking on the outside.​
  3. jcliv

    jcliv New Member

    Not in the render around the window. There may be a couple of small diagonal cracks in one or two of the bricks beneath the window near the ground, but if so they have been filled/painted over and haven't reopened.
  4. Phil the Paver

    Phil the Paver Well-Known Member

    Bearing in mind that all of the window/roof weight is on the outside skin of brickwork and as you say this appears to be alright I wouldn't worry about it.

    If the internal cracking is a problem and any filled areas have opened up again, I would be chopping the plaster off and having a look, though the inner skin of brickwork only goes up to the window seal and isn't load bearing as such all though it should be tied to the outside brickwork with wall ties.

    If the inner cracking hasn't moved after being filled, then I would fill any other cracks and decorate.
    FatHands and jcliv like this.
  5. jcliv

    jcliv New Member

    Much appreciated, thank you.
  6. Devil's Advocate

    Devil's Advocate Well-Known Member

    Almost certainly not a problem - at all.

    (Handsome house - enjoy :))
  7. FatHands

    FatHands Active Member

    Hi Phil.
    Isn't the load split evenly then?

    Thanks
    Fats (likes learning)
  8. joinerjohn1

    joinerjohn1 Screwfix Select

    Anyone else sat there with their head tilted over to the left, looking at the pics ?? :D:D:D:D:D
  9. Phil the Paver

    Phil the Paver Well-Known Member


    Hi fats, no the load is always on the outer skin, hence why inner skins can be built is breeze blocks, though the walls are tied together this is more to stop them bowing out.
  10. joinerjohn1

    joinerjohn1 Screwfix Select

    [quote="Phil the Paver, post: 1280141, member: 106916" the load is always on the outer skin, hence why inner skins can be built is breeze blocks, though the walls are tied together this is more to stop them bowing out.[/quote]


    Roof loads are always built on to the inner skin. Windows are built into the outer skin, but shouldn't carry any loads. Lintels carry the loads (and should be used on both outer and inner skins) ;);)
  11. Phil the Paver

    Phil the Paver Well-Known Member


    Roof loads are always built on to the inner skin. Windows are built into the outer skin, but shouldn't carry any loads. Lintels carry the loads (and should be used on both outer and inner skins) ;);)[/quote]

    Not in a bay window they not, bay windows normally go to roof height and not have brickwork above them, so the inner skin normally stops at sill height.
  12. joinerjohn1

    joinerjohn1 Screwfix Select

    If you look at the OP's photo's , you'll see the bay window is only for the ground floor room, so there's a lintel holding the outer (and inner) skin where the window opening is. ;);)
  13. Phil the Paver

    Phil the Paver Well-Known Member


    Sorry you've lost me, what have the lintels holding the upper floor up got to do with the bay below them, in this particular bay the inner skin is not load bearing, the windows and pitched roof are all bearing on the outer skin, as they are in most bay windows.​
  14. Devil's Advocate

    Devil's Advocate Well-Known Member

    I think what Mr JJ is saying is, if the main house roof is supported by the inner wall skin, surely there must be a proper lintel running along that inner skin before the bay window extends outwards?

    Ergo, the inner wall - which is showing signs of cracking - is the one bearing the main house roof?

    (In which case what I said earlier is bar locks.)
  15. jcliv

    jcliv New Member

    Thanks for all your input:)

    I went back over to the house last night, and while there aren't any cracks on the outside wall under the window, there is a fine crack in the render running from the top corner of the little piece of roof over the bay window, to the corner of the bathroom window on the upper floor. Looking back, the surveyor did comment on these cracks, and indicated they were cosmetic. Does that change anything?

    Apologies for the sideways photos :rolleyes:
  16. joinerjohn1

    joinerjohn1 Screwfix Select

    Phil, as I stated in an earlier post,,, the roof doesn't ever "bear on the outer skin" neither should upvc windows "bear on the outer skin" Just to clear this up. roof timbers/trusses always bear on the inner skin of a cavity wall. Windows don't bear on the outer skin, there's a lintel above the window to do all the weight bearing. Wherever there's an opening through both skins, lintels are used to bear the weight of the block/brick work above them.
    The inner lintel may well support the upper floor, but it also supports everything above that, up to roof level.

    (I think you may be getting confused over the use of the word "bearing" ;);)
    FatHands likes this.
  17. jcliv

    jcliv New Member

    Also, if we wanted to get somebody to look at this, is it something a builder can advise on, or do we need a surveyor/structural engineer?

    Cheers
  18. Phil the Paver

    Phil the Paver Well-Known Member


    No disrespect but I've been a builder long enough to know what I'm talking about.

    Show me the lintel that is holding the pitched roof on the bay window????

    No didn't think so, the pitched roof is bearing on to the window frames which are in turn bearing on the outer skin of brickwork, any brickwork at the lower level that inline with the upper brickwork is not part of the bay, the bay is the point that's beyond that line.

    O and a matter of fact not all roof wall plates are on the inner skin of brickwork/blockwork, quite often it is on the outside if the roof has a swallow pitch or even a flat roof.
  19. joinerjohn1

    joinerjohn1 Screwfix Select

    Ahh, I've just cottoned on.. You mean the very small pitched roof on the bay window itself.... There will still be a lintel supporting the inner and outer skin in the opening into the bay window. There will be a wooden wall plate on top of the bay window though. ;);)
  20. Phil the Paver

    Phil the Paver Well-Known Member


    Glad we sorted that out :)

Share This Page