Metal roof – cut edge with a saw?
GreatWhiteNorthGuy
| Posted in Construction Techniques on
Hi guys!
My wife has volunteered my services to put a metal roof on her sister’s home. It has every pitch of roof from 2:12 to 8:12 and a variety of valleys. I can handle the metal on the standard roofs, but what do you do for the valleys? Do you cut it with a carborundum saw? This, in my opinion, would only create heat and burn the paint and galvanizing off the metal. You’d be left with a raw metal edge that would start rusting as soon as the first drop of rain touched it.
Any suggestions as to how to cut the metal would be greatly appreciated. Of course, since it is an in-law I could saw cut the metal. Then none of her other brothers or sisters (11!) would ask me to do a roof for them! Thanks for your suggestions.
Replies
When I put my standing seam metal roof on, I had the same question and the same assortment of hips and valleys and unequal pitches. Roofing supplier said DO NOT saw it for the very reasons you expressed. So I spent a lot of miserable days with a couple sizes of hand shears and finished the roof with a lot of blisters and cuts on my hands and fingers.
If you are installing a ribbed roof, like an ag profile, I would recommend biting the bullet and buying a pair of electric shears. (My Porter Cables were about $200 and change, if I recall)
Recently, on one of my home projects, I made a jig and cut some standing seam with a sawsall and it turned out ok, but I only had a few cuts so I wouldn't swear by it yet.
I'll be interested to see what some of the more experienced folks on this site have to offer.
Edited 7/4/2002 11:18:05 PM ET by Notchman
Thanks, Notchman. I thought about electric cutters or a shear, but I look forward to seeing what others have in mind, as you are.
Get the electric shears and be happy, are you being paid for this job? They can a least buy the shears for you!
Paid? What's that?
I cut my metal roofing with my skilsaw. I think the blade I used is called a friction blade. It is a metal disk with slots cut radially around its perimeter. I wouldn't think it would cut much based on looking at it but it did great. I think it was made by vermont american and is only for cutting sheetmetal.
I did accidentally grab the wrong skill saw while cutting one piece and wondered why it was spraying so much hot shrapnel. It turned out I was cutting with a carbide tooth framing blade. The blade seemed to tolerate it, the cut was a bit rough but ok, the only problem is the shrapnel
Always wear eye protection.
karl
at the risk of opening myself up to derision, when I had a metal roof to do several years ago, I bought a B&D 'rotary power cutter' (model # 7975) - this machine resembles a sabre saw, but with hardened disk shaped steel blades, varible speed, forward&reverse - will zip right along cutting an undistorted line, until you reach a rib, (will do just fine on corrogated) where some hand work is necessary - about $60 15 years ago, I don't know about availibilty today - that plus right, left, and straight snips will do anything I've ever run into - here's a pict of the box, the tool is at a jobsite -
I've also used one of the cutters Dave mentioned. They work pretty well on flat stuff. But as Dave mentioned they don't do ridges.
They're definitely great for long cuts parallel to the ribs.
One nice thing about egotists - they don't talk about other people.
Boss, I turned the nibbler head upside down and can cut across the ridges. It is a little awkward holding a drill body upside down in order for the nibbler head to be right side up, but the learnig curve is short. With the drill handle pointing up, you are able to lean the nibbler head enough for it to traverse up or down over the ribs. I cut my sheets from the back because the only place a scribed line or chalk line doesn't mark is down in the inverted ribs. Cut from the face and the only things you can accurately mark are the high ribs. Saves me a few minuets of connecting the dots over a front layout cut.
If you are working alone, as I do, you should also clanp the sheet down before starting your cut. When they are face down, the only contact with the support suface are the ribs. The KET nibbler sets up enough vibration to walk the panel off of the stack or saw horses. A couple of quick grip clamps work nicely for this and a couple more on the roof make placement and adjusment of panels a lot easier.
Dave
Ya - to clarify a little more, in the situation where you are cutting across a length of roofing at an angle as would be needed at intersecting roofs, the rotary power cutter has trouble staying on the line at the tall ribs (some styles of roofing have a short rib between the tall ones that represents no problem) - the machine will get across the rib and if you are cutting the right direction, will swing wide of the mark so that a few moments with another tool will clean it up - going straight across the panel, it works pretty well, and it is not bothered much by the ribs at the edges of the panel, only the two in the middle -
it does cut quickly, certainly eye protection is alway called for, but you don't need hearing protection -
so... gwng - - ya should get your sister in law to buy you one of each - do you plan on sealing the roof panel to the flashing in the valleys? how?
I use a shootboard and my 77, they make a carbide tipped sawblade just for cutting metal with and they work great, blade life is short and they cost about 45 bucks a blade, I always figure in at least one blade where there are a lot of hips and valleys. The shoot board protects the metal from scratches and keeps the metal from flopping around, which reduces burning and binding.
You're gonna have raw metal exposed no matter how you cut it and waxing will only protect it for a few months.
I'm with Dave on the nibblers being pretty good and on the safety recommendations.
I used my circular saw with shooting board but for a blade I just took an old plywood blade and put it in backwards. Figure five bucks for the roof.
My main contribution to this thread is to ask who made the decision that a metal roof was the right way to go on this house. Roof designs like this eat up a lot of flashing, labor and waste in surface metal. I like metal roofs but they seem to be the in thing and everybody wants one whether it is right for the house or not. Try to change their minds and save yourself a lot of trouble.Excellence is its own reward!
Hi Piff!
Seeing as I started this discussion I thought I should throw in a couple of photos. The question was, "Why a metal roof?" Well, take a look at this dog's breakfast! They've got everything from 2:12 to 8:12 and they're in the snow belt in Ontario, Canada. Metal, once the shingles are removed, is probably the best way to go given the low-slope roofs over the dormers. It just looks like it's going be more than a weekend's work! There goes my summer, again.
I'm with piffin on this one. Use the backwards mounted plywood blade, but I'd add one thing.............make sure to wear some decent earplugs.
There's always divorce...........
after seeing the profile you are working with, the rotary cutter is not going to do you much good - I speculate that 'nibbler' = slow (am I wrong?) - think you ought to buy one of those specialty blades for the skillsaw and have at it, - it is for a relative, after all - i've done a little with the backward blade thing and it works, altho it's scary - the radially slotted blade sounds just right - maybe you can get the job done and catch a little vacation for yourself - good luck -
I found a DeWalt blade for $ 10 that is supposed to do the trick. It's a throw away, of course, but you can't argue with the price. Thanks.
I've cut it with a skillsaw/carbide blade (in the fwd direction) with great results. Lots of hot shrapnal as mentioned though.
It was only in areas that would be covered completely with other metal/flashing materials however. It'll start to rust in no time if the cut edge is exposed without the touch-up paint.
Also the manufatcurer I used said their warrantee is only good to 2.5" in 12 pitch. Just check with your manufacturer to see if they allow the 2-in-12 you mentioned (Maybe the inlaws won't care since the deal is good already! ;-)
Ket makes an electric shear that comes with a nibbler head to use in place of the standard scissor type that comes with the shears. I got mine through Tool Crib fo about $180.00. I installed the nibbler head in what would be considered an upside down position ( kind of looks like an angle drill with the chuck pointed up). This give the tool a lot better range of motion, and it will clinb and dip right over the ribs of a metal roof. Because it nibbles the metal, there is no burned paint or hot metal flyinng around. The manufacture warrenty for the metal stays in effect just as it would by using hand tools.
Buy good hearing protection and use it, as well as safety glasses when cutting metal. Also insist that they provide you with touch-up paint for the ineveitable scratch or two that you will get it.
Final warning is to rig some type of fall protection for yourself and your helper. Most metal roofing has a thin layer of oil on it, when recieved from the factory. It will weather off in a few months, but at installation time it can mean treacherous footing.
Best of luck.
Dave
gwng,
Dave is right. The shears for rips and the nibblers for cross cuts. Wax the bottom of cut line to lubricate punch and die. I figure about $200 a square for this kind of roof. Alot slower than a gable or simple hip.
KK
sir; if you want a pro. looking job you must use pro, tools to cut the metal BOSH makes the tool -nibbler- try to rent it as it cost starts at $700.00- but you will be satisfied with results
Thanks for your suggestion. I'll look into the nibbler. And thanks to all others for their suggestions.
I have cut alot of pro panel, strong barn, etc. always used skillsaw, wood blade ran backwards, cuts very fast. Use hearing and eye protection. It will scorch the paint less than 1/8 on each side of cut but have never had any rust problems here (Illinois).
Hey;
I noticed sLowes has the specialty blade for 29.95, and just a 45 minute wait to check out if they don't have any other customers
Thanks for the suggestion. I think after all is said and done I'm going to try the saw blade and see how it goes. Thanks for all the inputs guys.