Advice on repair of sliding sash windows

[RobinBHM]

Hi all,

Im involved in site carpentry for a grade II* listed Georgian mansion and other buidings on the grounds

There is a cottage with 9 sash windows -there is a conservation surveyor expert overseeing the project he wants repair not replacement

Any tips on professional repair would be welcome, the issues are:

rotten cills
some have rotted bottoms of pulley stiles and outer facings

some lower sashes have bottom rails, lowers parts of glazing bars and stiles all rotted away at joints and above


Im mostly concerned with

-doing decent scarf joints

-whether its possible to repair in situ -tricky with the cill as of course this disappears under the weight boxes behind the brickwork

 

[johnnyb]

I always reckon cills are easy on sashes unless they are totally trollied replacing a full cill is awkward and not entirely satisfactory. when that rot affects the pulley stiles and front facings it doesn't add to much work as these need splicing in either case. it's fairly rare for a cill to be rott8ed front to back and usually through a leaky drainpipe. if possible splice those linings on the bench as there pretty thin. Jacob would say take them out replace bits(don't splice) then reassemble using the old wood.

 

[johnnyb]

showing a completely rotted cill.

 

[johnnyb]

showing the typical but unusual wedged tapered nailed dado used at the bottom of the pulley stiles.

 

[johnnyb]

showing the later victorian style of sash pocket behind the parting bead the older windows the pocket was central with the parting bead down the middle.

 

[Doug71]

Worth a quick look

https://www.spab.org.uk/sites/default/files/SPAB Technical advice note-Repair of wood windows.pdf

 

[Jacob]

I've done hundreds. Don't attempt doing them in situ unless its just a general service. Take them out and do it on the bench.

 

[niall Y]

I suppose it really depends on what is required. You can endlessly splice bits and pieces in, on -site but you may well find that the repairs prove unsatisfactory and need attention again in a few years time.

I found that the sashes themselves are best removed and worked on a bench in the workshop Within reason components can be spliced, though there is a sound logic to replacing whole elements as they will have a much longer life

The frame can be tackled in situ, with cills being easily replaced in their entirety.

 

[Jacob]

I always reckon cills are easy on sashes unless they are totally trollied replacing a full cill is awkward and not entirely satisfactory. when that rot affects the pulley stiles and front facings it doesn't add to much work as these need splicing in either case. it's fairly rare for a cill to be rott8ed front to back and usually through a leaky drainpipe. if possible splice those linings on the bench as there pretty thin. Jacob would say take them out replace bits(don't splice) then reassemble using the old wood.

Splice if it's easier but if you are doing it on a bench just replace the whole piece.

 

[Adam W.]

Don't bother taking them out, as you can take them apart from both sides whilst in situ easily enough.

Taking them out and re-fitting is a complete waste of time.

 

[Jacob]

Don't bother taking them out, as you can take them apart from both sides whilst in situ easily enough.

Taking them out and re-fitting is a complete waste of time.

Not if they are set in a masonry rebate or above ground floor etc.
They are often very easy to take out - chip away the plaster and pull out a few wedges.

 

[RobinBHM]

Many many thanks for all the advice and info.

Im back on site tomorrow so I will take some pics which should make it clearer.

 

[Bristol_Rob]

I would first seek a detailed brief from the conservation officer on what they want.

Often you will find conservation officers have different thoughts on conservation, preservation and restoration.

So it is imperative you understand them first. Then the level, scale and scope of repair will naturally bubble to the top.

Then you will know how to best approach the work.

Never forget it is OK to pass on a job if you are not confident.

There are many specialists that work on sash windows and doors.

Don't forget hiring them as a specialist sub-contractor and putting 15% OHP on top is an acceptable practice. You don't have to give away profit

 

[Doug71]

I find the Timbabuild epoxy fillers quite good, not cheap but can save loads of time.

I originally bought the starter pack to try it and now just buy the tubes as I need.

https://www.builderdepot.co.uk/timb...62HidGVwWk1UE-aKgMtHLaOFrbDyM2WhoCr5UQAvD_BwE
The ERC 10 is great for splicing and sticking bits in.

https://www.reddiseals.com/product/timbabuild-epoxy-rapid-cure/

 

[Jacob]

I would first seek a detailed brief from the conservation officer on what they want.

Often you will find conservation officers have different thoughts on conservation, preservation and restoration.

So it is imperative you understand them first. Then the level, scale and scope of repair will naturally bubble to the top.

Then you will know how to best approach the work.

More used to explaining to them what needs doing rather than having them tell me!

 

[RobinBHM]

I would first seek a detailed brief from the conservation officer on what they want.

Often you will find conservation officers have different thoughts on conservation, preservation and restoration

Luckily that is of no concern because we have an expert overseeing the project, He one of the UK’s most experienced Chartered Building Surveyors in the area of historic and Listed Buildings, he is Chair of the RICS Building Conservation Steering Group and he teaches building surveying, architectural history, building pathology and building conservation to undergraduate and postgraduates.

The frustrating thing is everything has to be restored not replaced - somewhat frustrating at times.

 

[Jacob]

Luckily that is of no concern because we have an expert overseeing the project, He one of the UK’s most experienced Chartered Building Surveyors in the area of historic and Listed Buildings, he is Chair of the RICS Building Conservation Steering Group and he teaches building surveying, architectural history, building pathology and building conservation to undergraduate and postgraduates.

The frustrating thing is everything has to be restored not replaced - somewhat frustrating at times.

Restoration can cost more than replacement.

 

[RobinBHM]

Restoration can cost more than replacement.

Yes I agree, fiddling about restoring stuff can be awfully time consuming.

 

[Adam W.]

And profitable, if charged by the hour or day.

 

[johnnyb]

having used both repair resins timber build and repaircare I much prefer repaircare. ( although it's even more expensive) it's more flexible and easier to use and more structurally strong. it's main disadvantage is it's harder to sand being flexible.