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Magee
01-02-2007, 11:01 AM
Hello all,
I need to reduild the flashing around the chimney of my house and am looking for some advice... It looks like Galvanized steel sheet is most common.
I'll be building a saddle out of galvanized steel sheet (I'm thinking 20 or 22-gauge). Here's a pic of a typical saddle:

http://www.rd.com/images/tfhimport/2003/20031001_Flash_A_Chimney_page003img003_size2.jpg

I'm looking for advice in joining the material... I have a TIG, but from my research it seems that soldering is probably the way to go for a number of reasons, not the least of which is the fumes created from welding the galvanized steel.

So...
#1: Should I be looking to use a different material given the fact that I have the ability to TIG it together? Is Galvanized generally used because of it's low cost and high availability? I admit I'm not the best at TIG welding thin sheet, but I could probably make it work with a little practice. Stainless sheet is a little bit expensive, but I wouldn't need much if that's the way to go.

#2: If I do decide that galvanized is the way to go... Does anyone have any experience they could share about joining galvanized steel sheet? What type of solder, flux, etc?
Could I use a MAPP gas torch or would a large soldering iron or coppers be better?
Many thanks.
Mike

SGW
01-02-2007, 11:12 AM
Has lead flashing gone out of style, or been banned? Galvanized won't last all that long.

But if you do want to use galvanized, regular 50-50 solder and tinner's fluid (acid flux) will do the job.

Weston Bye
01-02-2007, 11:14 AM
Last two chimneys I did I just framed a small saddle (about twice the size of that in your picture) from lumber and plywood. I flashed to that and applied roofing. One is 23 yrs old the other just 1 year. both doing well, so far.

loose nut
01-02-2007, 11:14 AM
A good soldering job on galvanised steel will last as long as the steel. In the "old days" all roof sheet metal work was soldered copper and it would easily last 50 to 70 years (galvanised won't last that long but coppers is $$$$$) if done right.

Swarf&Sparks
01-02-2007, 11:31 AM
Don't go anywhere NEAR zinc (galv) with a TIG. If nothing else, you're gonna spend some hours or $$$ cleaning/replacing your torch.
TIG dc electrode positive has to be seen to be believed when it comes to sucking zinc, even when I thought I'd prepped the metal inches back from the HAZ.

Evan
01-02-2007, 04:44 PM
Solder it. A propane bottle torch and some 50/50 lead solder with zinc chloride flux brushed on will make very quick work of it. You aren't building a piano.

wierdscience
01-02-2007, 09:19 PM
I would use copper and tig it.It will cost more,but it will be the last one you will need.

HWooldridge
01-02-2007, 09:52 PM
You can also seam and crimp it. I think it's called a "Pittsburg seam" by sheet metal men.

tsmartin_98
01-02-2007, 10:11 PM
Another vote for copper here.
TS

kendall
01-02-2007, 10:39 PM
galvanized is very cheap, and does last a lot longer then you would expect, it also retards growth of moss etc on the roof.

copper is not cheap, but lasts almost forever, drawbacks are that it is known to produce green streaks on a roof and with time, the eaves of the house.

In my opinion regular 50/50 60/40 with decent prep is perfect, anything higther temp will burn off the zink and eliminate any advantage of using the galvanized.

I have done a lot of roofs, and generally folded lap seam them, no worry about solder etc. Depends a lot on expected conditions, in the snow belt, solder is preferable, to prevent snow build up from allowing the melt to flow through.

Make sure you have suitable support under the ridge on it though, it's a favored position to stand on when doing anything to the chimney, and for re-roofing etc that area serves as a perfect catch-all for tools, lunch boxes, shingles etc. A simple ridge of 1x with V legs provides a lot of support.

Ken

dicks42000
01-03-2007, 02:22 AM
OK; something more than an amature tin basher here....Although I mostly do HVAC work....
What you show there is called a Cricket flashing. Can be stick-built as well, as someone else said.
As far as materials, for lower cost & moderate life span, go with galvanized. DO NOT bother to try & weld galv. by any process. The fumes are deadly (seriously, with out adequate ventilation....) and will contaminate a TIG tungsten....Soldering is so much easier...use 50-50 and flux, as others have said. A low grade heat source like a cheap propane torch will make burning away the Galv. plating harder. Also don't over look spot welding. I join most bits of custom made fittings using my ancient spot welder (Lincoln). Harbour Fright & others sell a Chicom copy that even works...Paint your joints after soldering with Galvalume paint for better corrosion resistance.
Seams are another option, Standing seams can be water tight, Pitts seams not as easy....
Copper is the Rolls-Royce of roofing mat'l. Use it if you can get/afford it. It is readily joined by soldering (if clean & fluxed).
Caulk all of your nail/screw holes, counter flashings, regelets etc. Remember that flashings get hot & move. That's why you use expansion joints, counter flashings, standing seams (that may not seem water-tight), storm collars, etc. to allow for expansion. Think of roofing & flashing as fitting together as a system, like ducks feathers or fish scales. That's how they keep the rain out.
There are a few thoughts, anyhow....
Rick

Evan
01-03-2007, 02:33 AM
Yep, a sloped roof needn't be watertight. Water doesn't run uphill. The flashings should be installed so that any place the water runs off it is onto another surface that eventually directs it off the roof. The overlaps on the large three flue chimney I have aren't sealed at all and water never comes in. All you need is sufficient overlap to prevent melting snow from reaching the level that it runs over the top of the flashing underneath the lap.

ptjw7uk
01-03-2007, 06:29 AM
Never heard of using galvanised sheet for flashing work here in the UK, its lead or zinc sheet.
The lead is joined by 'burning' joining by welding lead fillet, the zinc by soldering.
Lead flashing will last the longest but zinc will last upto 100 years as on my roof, slate with zinc flashing.
Although around the chimney its is lead

Peter

Norman Atkinson
01-03-2007, 06:42 AM
Mike,
Basically, the other answers are quite authoritively correct.
Copper is what every self respecting building in " Sound of Music" is done.
Lead is what every cathedral in England has but the United Can Company has tin or terne plate.

What has BMW and the rest of modern cars got? Galvanised metal!
Digressing, I recall a body repair film on how " Beemers" were repaired after crashing---- repeatedly. If you recall, car bodies are spot welded and even the number of welds in a section are counted. When each spot is created, the two plates are fused together- after the zinc is melted, forced away so that the steel can join---- and then flows back to seal the rustproofing.

So, repairs, which you are doing, should be stitch welded with a Mig and not a Tig.

I was mulling over the answer and asked myself " What if the guy hasn't got a stitch facility on his Mig?" One can use a cheaper Mig to do a plug or sort of spot weld.

Does this help?

Norm

JoelM
01-03-2007, 09:20 AM
I've done a lot of galvanized with TIG using silicon bronze filler rod. It isn't
really welding, more like soldering, but it makes a fairly strong joint. Just keep
the heat down and stay away from the fumes.

ptjw7uk
01-03-2007, 09:43 AM
The galvanised sheet used in cars is not mormal in that one side has a reduced thickness of zinc this is to enable it to be spot welded if you try to spot weld normal galvanised sheet you can get a build up of zinc oxide which will reduce conductivity.

Rolls royce I believe tried using galvanised sheet in their body work but do not know if they still do

Peter

Magee
01-03-2007, 10:03 AM
Thanks to all for the replies. As always, there's tons of useful knowledge here.
I'd love to use copper, but with today's prices (copper would have cost about $300) I just can't bring myself to spend that kind of loot.
I like the idea of seams. I hadn't thought of that, but since I have little experience with them and it looks like I'll be getting this done today, I'm going to try to keep it simple. I did some testing with galvanized sheet, 50/50 solder and Zinc Chloride flux. Seems to work well. I'll likely go that route.
There's also a local supplier down the street that will sell me all the 304SS I'd need to get it done for about $100. I already have the filler rod, so I may consider stainless. There's a nice coat of frost up on the roof at the moment, so I've got an hour or so to kill before I can get up there. Plenty of time to make a decision and change my mind 2 or three times ;)

Wish me luck!
Thanks again.
-Mike

GKman
01-03-2007, 10:46 AM
I've built 'em wrong. I've built 'em right, repaired 'em, specified 'em, inspected 'em. I hope I never see another one but if I do I can put it on so it looks good and won't leak.

The one pictured isn't big enough to need a "cricket" (the pup tent shaped thing) With a flashing up under the shingles and elled up 4" and a counterflashing attached to the brick flue down over it the water would have to puddle 4" deep to leak in. It would be going between the shingles long before that.


If you look at the photo, there is no need for a seam. The pup tent shaped piece is soldered on top of the flashing. Why would you cut out a triangle shaped hole under it?

If it is a wide fireplace flue, I'd vote for the wood framed cricket. If you make it from metal, you can fold it up from one sheet and only have the two ends of the ridge to scrap in a couple of small rectangles with a vee cututout to cover where the split piece opens. Try it with a piece of paper or cardboard. I'd trust pop rivits and silicone more than solder for them and it's easier and faster.

From my experience, about 60 seconds with a propane torch will convince anybody that you can't solder a flat seam with a torch. The metal will instantly buckle and open a big fish mouth. Thats why tinners use soldering irons and make a darned good job of it.

The main mistake on masonry flue flashings is connecting the flashing (attached to the wood framing) to the counter flashing (attached to the chimney). On a two story house I've seen a crack in a gob of tar 3/4" wide where the wood framed house and masonry chimney moved independently.

Thanks for listening.

Peter S
01-03-2007, 07:20 PM
Norm,
BMW used to (still have?) have a little petrol stove option for their cars (to keep them warm overnight in German winters I guess), but not sure how they flashed the chimney...copper? Kiwis would use bits of flattened corrugated iron, silicone and pop rivits, but we are a bit rough out here....Happy New Year!

RobDee
01-03-2007, 08:13 PM
When I built the 'cricket' for my house, very similar to yours, I used copper and soldered it.

TIG or MIG on zinc coating gives off toxic fumes. The other problem is that the zinc ‘migrates’ away from the welded joint which can lead to premature breakdown.

If you do use zinc coated metal then solder it but my advice is to bite the bullet and go with soldered copper.

Evan
01-03-2007, 09:04 PM
There isn't any point in spending the money for copper unless you plan on living there for another 50 years or more. Galvanized steel holds up just fine for a long time. The galvanized flashing and gutters on my house are around 40 years old and are still good.

pntrbl
01-03-2007, 09:19 PM
I just did a roof last summer and I've been joking about putting a 40 year roof on a 54 year old guy ever since ....

Is that optimistic or what?

SP

RobDee
01-03-2007, 09:58 PM
There isn't any point in spending the money for copper unless you plan on living there for another 50 years or more. Galvanized steel holds up just fine for a long time. The galvanized flashing and gutters on my house are around 40 years old and are still good.

You may have a point. We put a galv. roof on the barn when we built it and if I remember correctly the supply house said it would easily outlast shingles.

wierdscience
01-03-2007, 11:33 PM
There isn't any point in spending the money for copper unless you plan on living there for another 50 years or more. Galvanized steel holds up just fine for a long time. The galvanized flashing and gutters on my house are around 40 years old and are still good.


BUT,galvanized flashing like many things isn't what it used to be.The new stuff I used was 24 ga. and it rusted in less than 4 years.

Evan
01-03-2007, 11:54 PM
There is more than one type of galvanizing. Electrolytic just puts a flash coat on and isn't worth a pinch of shjt. To be any good it needs to be hot dipped. All of the steel parts on my '59 Land Rover are hot dipped galvanized and you can't find a tougher environment than an automobile on winter roads with salt. Virtually all of the steel parts are still rust free.

Fasttrack
01-04-2007, 12:05 AM
"To be any good it needs to be hot dipped."



Unless its hardware, imho. I'm sure hot-dipped bolts outlast electrolytic galvinized ones, but the hot-dipped hardware that i've found at Home Depot, Menards, etc is worthless. The hot dipping screws up the threads so you have to wrench the nut on the whole way... it gets super hot even if you use some oil on the threads. By the time your done, the nut has cut all of the zinc off of the threads anyway. :(

wierdscience
01-04-2007, 01:39 AM
"To be any good it needs to be hot dipped."



Unless its hardware, imho. I'm sure hot-dipped bolts outlast electrolytic galvinized ones, but the hot-dipped hardware that i've found at Home Depot, Menards, etc is worthless. The hot dipping screws up the threads so you have to wrench the nut on the whole way... it gets super hot even if you use some oil on the threads. By the time your done, the nut has cut all of the zinc off of the threads anyway. :(

They are supposed to have HDG nuts too that are tapped oversize to accept the HDG bolts.

wierdscience
01-04-2007, 01:42 AM
There is more than one type of galvanizing. Electrolytic just puts a flash coat on and isn't worth a pinch of shjt. To be any good it needs to be hot dipped. All of the steel parts on my '59 Land Rover are hot dipped galvanized and you can't find a tougher environment than an automobile on winter roads with salt. Virtually all of the steel parts are still rust free.

Unfortunately,HDG sheetmetal is hard to find,galvalume is the most common,but still isn't going to last long.

Real Tin dipped sheet might be an option,but the copper to do that job still wouldn't cost $25.Find a roofer that uses copper and you can probibly get all the scraps you need for less than that.

Evan
01-04-2007, 02:36 AM
I have a 4' x 8' sheet of 22ga copper that I have been hoarding for about 15 years. No idea what it is worth now.

Norman Atkinson
01-04-2007, 04:42 AM
Absolutely fascinating--- indeed quite rivetting! Oh, dear.
Despite my somewhat zany approach, I can still confirm that copper is used extensively in France. I have just returned from my little appartment in the Tarentaise region and found that the roof of the balconies above mine have been copper bottomed. These are at 1800 metres and protect those who are underneath from snow melt. Can't have snow melting down the neck when one is drinking 'champers' old boy!

Again, I spend a little time in Austria- 'Beemer' country but have yet to find a heater for them. When we bought our two Mercedes such an option was not offered. Seriously, Peter S, but my son's French registered Renault Twingo had galvanised high strength low alloy steel panels. One doesn't have to be posh to get 'bells and whistles'.

Moving towards thickness of coating of tin, zinc or whatever, I recall that even in the early 1950's, tinplate thicknesses were such that two thicknesses were supplied on cost grounds alone. We are back to the old cost accountancy thing because it is not new. I recall tins of dried eggs and milk coming over from the States during the last War- and they were not tinned outside but painted or lacquered. My memory, like the tin coating is getting thinner!

However, I was very involved for a short while in tin plate and later, after retirement did a City and Guilds in Motor Vehicle Repair- got double distinctions, and was quoting from hands on experience then and later.

To move a little sideways and putting my more real accountancy hat on, I would take a very dim view of any house which had been " Jerry Built" or repaired. I also spend quite a time in Scotland. The nom de whoosit of Aviemoron was not plucked from thin air. Aviemore is a place on the banks of the River Spey and my neighbours are the Loch Ness Monster and 'Big Ears' and Camilla on the other. Many farm outhouses, barns, byers, boyers or whatevers were thatched. The thatching has now been replaced with corroding galv sheet. I wouldn't give a pinch of Chinese sh1t for anything of that standard.

Importantly, I am not alone in that view. Sorry, but that remains my almost professional opinion.

Norm

Evan
01-04-2007, 10:26 AM
Norman,

I don't know if you realize the difference in building standards that exists between North America and Europe. I don't mean the official building codes although that is a part of it.

Here houses are built to last perhaps 50 to 100 years, perhaps the life of the owner. In Europe houses are commonly built to last for generations as the expectation was/is that generations would live there. The quality differences are very obvious and I was asked more than once if "we" really lived in wooden houses "over here". Houses built of wood are considered by many "there" to be essentially emergency housing for short term use.

I am sure that ordinary galvanized steel would be relegated to perhaps the covering on a garden shed and not much else. On one occasion while walking in Germany we came upon a nice but quite ordinary garden with a low somewhat decorative chain link fence around the entire back yard, most likely to keep the dog(s) in or out. The entire fence was constructed of stainless steel.

Norman Atkinson
01-04-2007, 11:06 AM
Au contraire- or something like that.
I was in Halifax NS in 2005 and visited the delightful area until a pair of Hurricanes or whatever ended the travel bit.
I was delighted at the quality of the homes- as well as the people.
Certainly, my daughter lived in a house which would have been re-built- after the Halifax Explosion in the First World. Her neighbour had seen and lived there at the time.

Here in the North East of England, many houses, brick and in terraces date from --- before 1865. Before John Dobson who designed many of them were literally shoved up to house the workers coming to the then new factories and mines.

None of my houses are old in that sense but I was born in a pit row in a house which was bought for £250 in 1930 odd- 500 $? but even then the original cost was a handful of sovereigns. My Spanish home would have cost- would you believe- less than a basic Mini Minor car which was £457. I bought at £7500- the price of a Volvo estate car. My old home is still there at perhaps £150,000 and the villa at £250, 000 to £300,000.

I may have gone slightly off track but it still suggests that based on my limited knowledge of Canadian prices and the assured quality of what I have seen there, it is still worth the better materials. I know all the points about wooden houses. Austria is full of them- and with tongue in cheek- my home in Aviemore is actually on a timber shell. Look it up- Dalnabay, Aviemore PH22 1TA. Mine's a semi- detached one.

It was, as I said, a professional answer. With more than a touch of hyperbole, the family castle fell down.

Cheers- enjoy this new retirement thing!

Norm