Joining Galvanised Guttering

[ColG]

Hi all,

I'm happy soldering copper however, when joining galvanised guttering sections, is it the same process - clean, flux, heat, solder?  Are there any special fluxes/solders/heat sources required?

Thanks in advance for responses.

Colin

[Punch]

French guttering is not galvanised it is just zinc.

You need The "tinmans" 33% eutectic solder usually is called a bagette de soudure à l'étain in France and a gas fired copper iron which should not directly contact the zinc for too long as you will have a big holes appear very quickly!!

You will need to use a proprietary flux décapant. Decap express 841 is a make I use sometimes.
New zinc will solder well. You need to clamp the two gutters in a gutter clamp so that they are not under tension when soldering and then tack in three places. You will need to rub the iron tip over a bloc of "sal ammoniac" from time to time to remove oxidation and keep it clean. remove all acid residues with clean water. There is a knack in doing it properly and you can easily burn a hole straight through the zinc if you have too much contact.
I am lucky to have employed a French roofer for seven years so have become adept at the soldering side of things. Here are a couple of photos of some I have done recently . I cut my own holes for downpipes and solder all round the flange. The joint is very strong.
I must stress that the above is just a brief summary and there is quite a bit of skill to it , but with practice on old scraps of zinc it should be fairly attainable.

Photo 1

Photo 2

www.punchardrenovation.com

 

 

[UlsterRugby1999]

I'm no expert - but I have used a special mastic which secures the guttering and downspouts very securely and needs no special skills. You can get it in BricoDepot for circa 7€ and it works very well.

[Punch]

[quote user="UlsterRugby1999"]I'm no expert - but I have used a special mastic which secures the guttering and downspouts very securely and needs no special skills. You can get it in BricoDepot for circa 7€ and it works very well.[/quote]

Yes,  There is a zinc mastic available for the DIY market which will work to a certain extent on straight joints but there are other aspects of using zinc that just have to be soldered. The only proper way to do it is to solder it. In my case I have to give a 10 year guarantee so I couldn't trust a mastic.

 

[Gluestick]

Mastic won't successfully bond long lengths of guttering.

Additionally, it tends to move as the building contracts and expands; breaking the mastic seal. Mastic doesn't possess the essential mechanical strength.

There are two-pack epoxy products used. Mainly in the USA for Galvanised Mild Steel Guttering, though.

Interesting little article on soldering gutters here.

[Chancer]

On galva I always solder but generally tend to use plastic now as I am working at height and it is lighter and somewhat safer for me.

I have used the cheapo plastic Brico depot guttering but it lacks a rubber seal between the joints, the colle PVC glues it but doesnt seal the joints so I now use a cheapo no name grey Sikaflex copy which also has great mechanical strength and flexibility.

It has worked well for a couple of "sunday" downpipe and tee joints, you know the ones when you never have he correct bits so have to resort to bodging.

[Gluestick]

As a point of interest, JR, what do use for soldering Galvanised Guttering?

i.e. iron; flame;??