Galvanised steel guttering.

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AJB Temple

Finely figured
13 Oct 2015
Reaction score
Tunbridge Wells
I am finally getting round to fitting new guttering to my newish buildings. Obviously I chose a time to do this when summer disappears and we get daily deluges. Today was great - it started with the cats and dogs just as I was fitting my first downpipe and S bend.

I wanted copper, but the price is just crazy. As in triple. The main barn has plastic guttering and it is badly installed and useless. So I have decided to use galvanised steel guttering, downpipes and fittings everywhere. The quality is superb. I went for this range as I like the profile and I can use different sizes for different applications. Steel Gutter - 100mm Galvanised

I have two questions for those of you working in metal. 1) I need to cut holes in the gutter for the water to drop through the clip on hoppers into the downpipe. So far I have only done one and did it with a V cut and then straight tin snips to cut the hole, then hammers the cut edges with a ball pein to tidy it up inside the hopper chute. This works fine but is slow. Is there a better way?

2) A pro roofer on a you tube vid I watched (Robin - a sensible bloke on Skillbuilder I think it was) says the guttering etc should be cut with a hacksaw only, not a powered saw. He reckons power tools heat up the galvanic film and could result in corrosion later. Can that be true?

The product is reckoned to have a very long life and I want to get the installation right as I prefer to do jobs once only. Cutting thin moulded sheet with a hacksaw is not fun. I may have to make a jig or box to hold the stuff steady.
not having used steel guttering surely any cut however done could result in corrosion later unless treated . and why not use a hole saw for the outlet even if you do it slowly with a cordless drill. the installation manual mentions burning a polymer layer if using an angle grinder.
I like the aluminium moulded on site stuff. they turn up with a roll of flat, and you pick your profile, and wham, the shaped gutter comes out the other end of the machine. In any length so theres never a leaking join.
Andy - do you mean the electric nibblers? I don't mind buying some as I have about 300m of guttering to hang, and a lot of down pipes and hopper outlets to cut, but I have never used electric nibblers and have no idea if they will do the curved profile and complex folds of these gutter profiles.

Thanks Mike. I agree. I was using a Bosch workmate thing with some pegs in the holes, but I have now tabbed up a ply box for gutters and a narrower one for downpipes.
When you cut zinc coated steel with a properly set up guillotine, some of the zinc is dragged over the cut edge and gives a bit more protection to the exposed steel. In practice in site you want to get as smooth a finish as possible to decrease the exposed surface area of steel. One of the easiest approaches assuming your downspouts are big enough is to cut a cross and then bend the flanges downwards (into the downspout). The only area you have to worry about is the end of each cut. I would treat all cut edges in this application with a zinc rich paint
i did our whole house using the galvanised guttering last year, I used a drill with a hole cutter running in first gear, cut real nice, think I used about a 90mm diameter cutter.
Electricians use chassis punches for cutting perfect holes. Drill a hole put the two parts together with the bolt and nut. When you draw up the bolt it punches out a perfect hole. A 4” one might be spendy but you may be able to recover some of the cost by selling it after you’ve finished.
Thanks, Hornbeam and Murdoch. I will get some zing paint and try a hole cutter.

Edit - Imspector. Never heard of a chassis punch. I will investigate. It has to work on curves without deforming the gutter.
I'm just finishing doing my house in that very stuff, i used the black mind. I followed the instructions and cut by hand with a hacksaw, it is laborious, no way around it unless you get the angle grinder out but having read the instructions I chose not to take the risk. For the outlets I cut the V by hand with the hacksaw like you then filed the sharp bits off and left it at that, doesn't seem to need any further profiling and if you open it up too much you wont be able to fix a gutter balloon in (a must where I live due to all the trees). Its pretty fiddly stuff generally to get together and in the brackets (mines mainly rafter brackets with some facia brackets) and not a job I relish doing again soon. Still got one piece left to do, then the garage. Good luck.

Thanks Mark. I have been marking a hole on the gutter curve, using a bit of pipe as a template, cutting a small V and then using tinsnips to cut the circle from the V. I file off any rough bits then use a ball peen hammer to make sure there is a smooth, downward facing edge. It looks neat, but it is fiddly and slow.
Chassis punch is for flat materials. Round bottom gutters are not common here nor is galvanized gutters for that matter. Virtually all aluminium.

See attached video for Lindab gutter installation. Lindab are one of teh biggest mfrs in Scandinavia and northern europe.
Very important to turn the edges of the cut out down to provide a drip edge to minimise water holding onto the edge .
The electric nibbler I was using made short work of industrial factory box profile cladding.
I'm not sure if it'll suit your profiles but there a wonderful bit of kit.
Cheers Andy
Well, I can now say for certain that an electric nibbler is no use for cutting complex shaped guttering. It is incapable of dealing with the fold overs on each side and distorts the metal a great deal if you do get past that part. It is also no use for cutting holes to fit downpipes, as by the time I have cut a big enough access hole I may as well have cut a V with a hacksaw and nibbled it out with tin snips.

I didn't pay much for it and am able to return it, but I might keep it for doing some flat sheet work that I have coming up.
Made and fitted 12 metres of oak facia board today, hung 12 metres of gutter and brackets, fitted hopper, dressed cut out, fabricated S bend and fitted down pipe to drain. Mrs AJB cleared the ground around the sealed drain inlet. This took us all day. :oops: (Including fabricating another hopper connection for the utility room. It's quite slow to do a really nice job but it looks a great deal better than plastic.
Whoops! :mad:
Is there a run n hide emoticon....
Not your fault. It was worth a try. I have seen videos of a high end electric nibbled cutting corrugated steel. However, the video I suspect chooses ideal materials and does not mention the shortcomings. Such is life. It was worth a try. So thank you anyway.
Treat your cuts with Zinga cold galv. The gutters are not galvanised ie hot dip. Maybe flame sprayed or similar. They are up 5 years in a property I know and still seem good. FWIW those seamless ally pressed out gutters mentioned are fine, except that the corner joints and running outlets are joined with sealant. That is where they usually leak. Good prep and Sikaflex helps them last.