On 4 Aug, 22:34, Martin Hind wrote:
We're repairing sash windows throughout our Victorian terrace and need
to
replace cills on at least three windows, at present have two windows
removed and hopefully will start on third at weekend.

I'll also need to replace some of the inner and outer box linings but
this doesn' strike me as the tricky part.

Having never had to replace cills before turning process over in my
mind
and a couple of things crop up:

[1] A band saw might make light work of making joints in new cills.
Saw
would need to be portable, so table-top type, as no workshop here and
equipment stored in the basement. *Was thinking of Axminster AWSBS2:

http://www.axminster.co.uk/product-Axminster-AWSBS2-
Bandsaw-462917.htm

Comments appreciated.

[2] As to machining joints in new cills, it occurs that it might be
easier to rout housing joint in cill for stiles before profiling the
cill. *If this is true then rather than getting local timber yard to
supply cill ready profiled I'd need to do profiling myself last. *So
how to
go about this? Would I manage with circular saw or is more machinery
needed here?

Again all comments much appreciated.

TIA

Martin

Dear Martin
Some tips:
I have replaced literally hundreds of these - that's my business.

It is much easier if, as you have done, you remove the frame but there
is no need unless you are for other reasons
If you are doing it "in situ" - you need to cut each part of the style
at an acute angle to effect a scarfe joint.on replacement and to allow
the sill to be cut out and removed
The sill is best in double vac treated Scots pine with the treatment
done after fabrication
That is better than most hardwoods (Balsa is a hardwood!)
(See the earlier link on durabitly of timber)

Get the profile made up by a joiner to be exactly the same as the
original sill and cut it to shape to fit the syles etc and then have
it treated
prime all the end grain before fitting
put on a dpc and run the dpc up the sides some 6"
If you cant get it double vac treated dip all cut ends overnight in
and OS borne fungicide before priming and fitting
Use the Dulux Weathersheild green pimer or any heavy metal primer
(its an old Victorian trick to block end grain0

There is no need for any band saw
Any coumpound chop saw or even hand saws are fine

Make sure that if the original has not got a decent slope on it that
you adapt the new one such that it has a minimum of 10 degrees
Make sure each arris is well rounded and the front one has a radius of
at least 10 mm
Sharp edges cause paint failure
All box frame edges should be rounded to a radius of 1 or 2 mm and not
left sharp

Use a polysulphide mastic to make the joins with masonry (See DAS 68
from the BRE)
isoalate styles with thin (63 micron) poly by wrapping it round the
sides and top and stapling in place
Point in and backing plaster first
then cut off poly
then do the final coats of plaster or architrave to cover join
prime any bare wood early on
under coat before you put in the sashes
put in draft stripping (Reddiseals) parting and staff beads

paint sashes out of the box when flat so paint does not run

put in sashes with staples not nails in sash cords

check weights by using a balance to ensure compatability with sashes
Check and repair putty if duff

Use Window Care resin to fix back box frames if scafed in situ

Hope this helps

chris g