"John Rumm" wrote in message
...
VisionSet wrote:

I'm in the middle of replacing the sill section of a bay window. I've
knocked out the hole sill which cold bridged straight through.

I've replaced this with 2" aerated block as you can see and have started
the
form work to cast a new sill.

http://tinypic.com/view/?pic=2uj46m9

http://tinypic.com/view/?pic=4dcijcj

Now what would you do? As you can see, I have to avoid filling the
cavity in
the close up, and I have to not reinstate the cold bridge, so some sort
of
insulation between sill and blocks? Also I have not much depth to play
with
as you can see the window frame does not overhang by much, but I'll
probably
glue a weather bar along it. Does a DPC need to go in somewhere? I
believe
you usually fit a cavity tray kind of thing that is tucked into the top
of
my thermal blocks but this is custom and I won't find the right size. I
can
put 1200 DPC in somewhere - upturned against the blocks?
Suggestions welcomed.

I would have thought a can of expanding PU foam would be your friend
here! Fill the top of the cavity, and the the gap under the frame. Once
set, trim with a saw to your required levels, then shutter up your
casting and pour away.


Ah yes, that would be perfect for the irregular void at the end of the sill,
but against the thermal blocks, I'd rather use a thin sheet material - like
10mm. What comes that thin that would be suitable - I only need 0.5sqm.
Preferably free! I hate that foam stuff, so messy.

--
Mike W