Lead and GRP (non boaty but technical)

[Quandary]

My neighbour has a problem with the lead roof of his bay window. There is a secret gutter which is made up of sections of lead with soldered joints. One of the joints has parted and rain is running down inside the window frame. Apparently modern plumbers no longer do lead work and roofers are not too good at some of it. It seems to me that resoldering the joint should not be that difficult, anyone got any advice on preparation, dealing with the weathered edges of the crack, type of solder and flux to use?
We have been discussing the possibility of also lining the gutter with GRP, this would not seem too difficult but it would be critical to get a permanent bond between the GRP and the lead downstand as if water gets between it would be a serious leak problem. I don't want to advise cutting the lead to form a flashing though this might be possible. Having recently worked on my lead keel where, on tackling a chip, the manufacturers epoxy paint coating on one side came away in sheets with no effort, I wondered if this was just poor preparation/degreasing or is lead resistant to adhesion? I have since cleaned the keel with acetone and overcoated with coats of West epoxy with fillers to thicken it and short of destructive testing it seems to be adhering OK. Lots of recent flat or low pitch roofs around here are coated with polyester resin on mat with a grey flowcoat that looks like lead from a distance, would epoxy give better adhesion? Will weathered lead with its oxydised surface give a good key or would it be better to abrade to a bright surface?
Any technical advice would be welcome as I have promised to tackle it on the next dry day which could happen anytime in the next few months.

 

[Billjratt]

There are still a few plumbers/ people with lead-burning experience around. They needed them in chemical works like ICI and the like.
Tools are still available, so they must be in demand.
Proper roofers should be able to do it.

 

[bazobeleza]

Torch on lead / bitumen repair sheet, comes on a roll, would seem to be a remedy if you can't get the lead soldered up, bear in mind the lead is likely to be old, and work hardened and trying to solder it up may worsen the situation.

Normal 60/40 bar solder and the flux you can get from here

http://www.warton-metals.co.uk/fluxes-thinners.html

would do the trick if you want to tackle the job

 

[James_Calvert]

Long time ago I spent a few months working with a plumber who still did lead, and I recall sitting on roofs with him as he finished off welding together the chimney lead flashing. He used the tiniest oxyacetylene gun which produce a tiny blue flame about 1/4 inch long. It didn't look too difficult but took a very long time. We were using new lead sheet.

I'd encourage you to carry on looking for someone to do the job properly. It really didn't seem to be that difficult - any one who has learnt to weld with oxy ought to be able to do the job with the right tools, a bit of practice, and some patience.

 

[Cliveshep]

DIY way that works - scrape the lead shiny with a shavehook (triangular thingy on a handle used for scraping paint off), smear with Fluxite flux, use a small flame blowlamp and do it gently with plumbers solder, the red reel solder containing lead as used to be used for solder joints, (not the green one currently used as that is lead free). That way you won't get too much heat on the job, you need to leave the solder thick rather than run off. so use only enough heat to melt the solder onto the hot lead, whipping the flame away as the solder melts on. Other alternative is proper plumber's metal but still carefully control the heat. The flux is necessary or the lead will oxidise unless you have the oxy kit for proper lead burning and can run in lead.

 

[Quandary]

Thanks for all the responses, as usual the info. is relevant and helpful.
I had a rehearsal this morning with a couple bit of old lead on the bench in the garage and even there I found it very difficult to control the heat, it was too easy to burn holes in the lead particularly on a horizontal surface at the bottom of the narrow gutter channel with the torch upside down. Since it is not my roof I have contacted the owner to suggest he asks around for an old plumber who still remembers how to work with lead. However we are well out in the sticks here (Argyll) so he may have to resort to a bitumen patch which will eventually fail again. A local roofer would replace the whole roof (with GRP) but this seems expensive for a 4" crack and the rest of the lead looks sound. I am still trying to find out if a GRP lining can be made to stick permanently to lead in case we decide to try that.

 

[catalac08]

the foil backed bitumin adhesive flashing strip has a good life if properly applied, perhaps 10 years. Important thing is to clean the lead by use of abrasive paper and then warm the lead and foil before application when it will stick really well. This stuff is cheap so a double layer is best. The outer layer gives protection from sunlight of the inner and this should be ok.
Better to solder but once the lead starts to age and crack it will probably just crack somewhere else, or re-lead the whole gutter with new lead and then solder where required.

 

[nedmin]

Used to do lead cable joints years ago, which is similar.You need plumbers metal,ordinary solder is no good melting point is too high.Clean the area with a sharp knife or something similar.Dont use emery or glass paper as you will leave bits of abrasive in the lead,We used to use tallow but I doubt if you can get that now,I would think lard or mutton fat would do.You need a wiping cloth, I had a moleskin one,doubt if you can get them now! but you should be able to get the replacement.Put plenty of fat on the cloth using a bit of heat to help it soak in.BE CAREFUL AS FAT IS HOT.Next put some fat on the lead apply heat to the lead and rub the plumbers metal up and down the lead until it melts onto the lead,with care and not too much heat you can deposit the solder without melting the lead,when you get enough on use the wiping cloth to level it off and make it look neat.Keep plenty of fat on the cloth or you will burn it.Put fat on the lead also. Practice first. Even I would have to as its 50 years ago.! !