I have a bay window to repair with sash windows
and unusually no stone sub sill (see link below) instead their is a
wood sill,
which has rotted and been covered over with plywood.
I dont know if there was a sub sill originally.
My prefered method to repair would be to cast a new sill all round in
concrete, but my concerns are if I use a DPM between existing wall,
sash frame and new sill. It might not hold in place with the weight
of
the concrete (as their might be no grip).
If I dont have a DPM between sash and sill water might soak into the
frame and cause further rot / leaks.
Any suggestions would be appreciated from persons who know what they
are talking about and stick to the point.
Thanks
Martin
[IMG]http://i35.tinypic.com/i2tvt5.jpg[/IMG]

On 20 Aug, 21:07, Housemartin  wrote:
> I have a bay window to repair with sash windows
> and unusually no stone sub sill (see link below) instead their is a
> wood sill,
> which has rotted and been covered over with plywood.
> I dont know if there was a sub sill originally.
> My prefered method to repair would be to cast a new sill all round in
> concrete, but my concerns are if I use a DPM between existing wall,
> sash frame and new sill. It might not hold in place with the weight
> of
> the concrete (as their might be no grip).
> If I dont have a DPM between sash and sill water might soak into the
> frame and cause further rot / leaks.
> Any suggestions would be appreciated from persons who know what they
> are talking about and stick to the point.
> Thanks
> Martin
> [IMG]http://i35.tinypic.com/i2tvt5.jpg[/IMG]

Dear H Martin
If this were mine I would go back in wood as is using double vac Scots
pine and all the items previously specified on this group for double
hung sash windows

If, however, you want a subsill then unhesitatingly go and get  a
thinish preformed one (pre cast) with appropriate stooling and drip
grooves and angle grind it to fit the bays
Make sure it is put in low enough ( you may have to take away a course
of bricks outside to fit a decent timber sill on top
Chris G