Window position in cavity

[festive]

Quick question is it part of regs or Fensa or whatever that the inside face of Window Frame must be flush with the back face of external cavity block work?

I am fitting new window with stub still. If i fit this far back drip edge will not overhang external wall. Is there a minimum for this also? Thanks.

More concerned if we sell house someone will try and knock. At same time i dont really want to go looking for a new sill on a Saturday morning.
Tia

 

[JohnD]

Perhaps you are in London.

After the Great Fire of 1666, which spread easily between the close-packed houses due to exposed timber, it was ruled that no timber parts (e.g. windowframes) in the City could project beyond the face of the house, which must be brick or other incombustible material. It is still a practice in and around central London, and other towns following the style, to see windowframes set back, with the outer leaf of brick overlapping the frame, and they usually have no internal windowboard, but a deep external stone or brick sill, that the windowframe sits on. However AFAIK this rule was long ago superceded by other building regulations, and it is now just a local custom. To the eye of a person who grew up in these houses it seems normal. I think it looks better. Thatched roofs and wooden chimneys (!) were outlawed at the same time in the City.

Three hundred and fifty years is not long to builders.

If you have an old house, there are some people who will not like the look of windows that are not in keeping with the original style.

 

[crank39]

A stub cill is not designed to over hang the brickwork, it's mainly used when there is a stone cill which itself has the over hang, I think the bare minimum of over hang would be about 40mm. Generally the inner face of the window should be flush with the inner face of the outer brick, a stub will not over hang like this, you would need a 150mm cill for this.

1. Where a timber or metal framed window is to be replaced with a PVC window in cavity wall construction, unless the existing wall cavity is closed around the opening with non combustible masonry (i.e. the cavity is not open around the frame) it will probably be necessary to provide s ome form of noncombustible material to close the cavity before fitting the window. Materials that can be used to close the cavity include: • • • steel at least 0.5mm thick timber at least 38mm thick polythenesleeved mineral wool, or mineral wool slab, in compression when installed in the cavity • calcium silicate, cementbased or gypsumeither case under based boards at least 12mm thick. These recommendations apply to the exposed cavity not only where an existing window is replaced but especially when it is proposed to convert a window to a doorway. In this case the open cavity will be exposed where the wall construction is removed below the original window and the cavity will have to be closed as described above. Reference should also be made to Section 7 of this manual is this case in order to prevent the passage of moisture to the inside of the building