View Full Version : Corrugated Roofing Project

02-29-2012, 05:57 AM
I知 re-covering an L shaped awning that runs along 2 sides of my garden/blokey shed. It was previously covered in light canvas but I originally built the framework to accept corrugated plastic panels someday when the canvas rots out.

That time has come and I知 shopping around for white translucent polycarbonate panels. Translucency is important as part of the covered decking will be used for an outdoor work area and I want as much filtered, natural lighting as I can get.

One side of the frame has a five foot wide peak/ridge and I知 thinking about bending the panels (crossways to the waves) with a heat gun, instead of butting them at the ridge and covering the gap with a ridge cap/flashing of some sort. I値l have some cut-offs to test this with and see how it reacts. Any thoughts on that idea would be appreciated.

Has anyone worked with the stuff and had any good or bad experiences with installation?

Never having worked with the stuff, are there any pitfalls I should be aware of?

Are there any preferred methods for cutting it?

Maybe you know of a better product? Most manufacturers claim the polycarbonate is stronger than fiberglass, my initial choice, and I知 curious if this is so.

02-29-2012, 07:35 AM
I covered a new shed with clear-smoked polycarbonate panels, cutting to size with tin snips. Or maybe it was my heavy kitchen shears. Cutting is easy, cutting perfectly straight would require some other method.

I don't believe you can bend the stuff across the corrugations but lengthwise you don't even need heat.

Sorry but that is all I know about the stuff. Good luck.

02-29-2012, 09:25 AM
They make cap pieces, flashing for just about every side wall /roof application, and wall to wall application I can think of.
My Godparents did the old "Heat it and bend it" thing with their house ridge years ago, and have been patching it with duct tape and other things pretty much ever since.
I bought all my roofing from AGWAY, but I have to assume that Southern States or some other ag supply place would carry them too.....
Here's one site I found quick and easy...

Gib Etheridge
02-29-2012, 12:57 PM
When you bend the material the waves will try to flatten out, making the sheet wider at the bend. The first sheet will go down OK and probably won't crack all of the way through, but the next sheet will be hard to fit to the first.

It gets pretty hot in Tampa, so you might appreciate the naturally occuring ridge vent that you will get by using flat stock for the ridge cap, such as the cap material used for metal roofing, or 2 boards, or you could use a piece of the polycarbonate bent over the ridge making the bend parallel to the profile.


Nicholas Carey
02-29-2012, 03:16 PM
Our porch is roofed with transparent Polygal panels:


Not corrugated, but extruded honey comb, not unlike corrugated cardboard.


Here's a picture from our porch looking up through the roof. The 1x2 purlins aren't necessary from an engineering perspective. The architect put them there since we were working towards a contemporary take on Craftsman architecture.

http://farm4.staticflickr.com/3454/3929191381_e700218755_z.jpg (http://www.flickr.com/photos/handforged/3929191381/)
IMG_2170 (http://www.flickr.com/photos/handforged/3929191381/) by Handforged (http://www.flickr.com/people/handforged/), on Flickr

I like the stuff. Something like a 10-year warranty on the standard sheet. Comes in different thicknesses and different extrusion patterns for dialing in the desired support/wind/snow load requirements and for varying insulation values. Light transmission anywhere from 80% of visible light down to as little as 25% or lower. It can be coated with special metallic coatings (like you eyeglasses) for appearance and/or to control IR, UV and visible light transmission.

As I remember, it's not hugely expensive -- have to go back and dig up the receipts, though for details. Nice and light. Goes up quite easily. The edges need to be sealed with their special sealant and vent tapes, though and you want to use their glazing systems (aluminum extrusions):



02-29-2012, 03:40 PM
I have done lots of verandahs with the corrugated, and a few with the honeycomb.

The corrugated is much cheaper here in NZ. On the hip joints I would get a custom zincalume flashing bent up to suit.
On verandahs open at the sides to the elements, the flashing didnt need to be very wide at all because windblown rain was going to get in anyway. In practice, next to none gets under the flashing.

There are corrugated molded foams available for compressing under the flashing in more weather sensitive areas.

I remember once having a piece of the corrugated bend double from a strong gust of wind, it popped right back into shape with no damage whatsoever. I fasten with 'one shot' fasteners which drill their own oversize hole needed for expansion.


Mike DeHart
03-01-2012, 10:09 PM
I am currently replacing old weather worn fiberglass panels in my shop roof with white translucent panels. I think they are polycarbonate. I got them from Lowes. I tried cutting them with a sabre saw. That did not work. They chipped. Next try was with tin snips. That woks very well. Mark a line in pen across the peaks and just cut it like paper. To nail it you have to drill holes first. The holes should be at least 1/32" larger than the nail diameter. If you nail thru the panel it will crack. I drive a nail in each edge mid-panel to establish the right fit, but I do not drive the nail fully to the panel. Just far enough to hold and check the fit. Then I nail each corner, same way. Then I put a few down the centerline. If you start nailing at one edge and work across you can actually stretch the panel as you go since each nail will mush down a peak a little bit, pushing the opposite edge farther across the framing. Once I have the panel "tacked" in proper location and meshing with the others, I drive those nails down carefully until the rubber washer JUST touches the panel, without distortion. Then fill in all of the other nails that finish the panel. If you have to pull up one of the nails, place a short piece of 3/4" steel pipe in the corrugation valley next to the nail. Use the pipe as a fulcrum for the hammer claw and you will not damage the panel.

Hope this helps.

03-02-2012, 06:38 AM
Once again the collective bilge mind comes through with a bunch of great first-hand info. Lefty and Gib made good cases for not attempting heat bending, confirmed some of my suspicions and saved me some considerable grief.

MAMan and Mike, I'm going to try the snips as you suggest. I'll have to cut every panel (5 in all) but luckily the cut edges will all be under flashing so, if the cuts aren't real pretty, it won't matter. So that sounds like the way to go at this point.

On another forum a guy mentioned using a router or a skil saw with a fine tooth blade mounted in reverse. If the snips go too slow (or my hands can't manage that much shearing) I may try one of those. I've fabricated several other types of plastics and know they can be squirrelly under the best conditions. This is a diferent animal from what I'm used to though and it seems the trick will be getting it held down good with a guide of some sort, should I resort to a power tool.

Mike, good ideas about tacking the panels down and coming back to tighten them up. That makes great sense.

Thanks guys, you've all been a big help. I have the material now and, once I do some other prep like painting the area above the awning, will probably start working with it in the next couple days. I'll let you know how it goes . . . and check back if I run into any issues, maybe post a photo at some point.

03-02-2012, 06:53 AM
Our porch is roofed with transparent Polygal panels:


Not corrugated, but extruded honey comb, not unlike corrugated cardboard.

Wow, very nice job there . . . that covering looks great!

We're starting to see people using a similar material (temprorarily fastened with clips and lags) for hurricane shutters over windows and glass doors. So it must be pretty darn strong and particularly good for areas where you get a lot of goofy weather.

03-02-2012, 07:33 AM
As a guide I simply laid down a length of masking tape with one edge aligned to the cut marks. The tape gaps the valleys, though, and that is where some irregularity occurred on mine. Since you can hide the cuts I'd say you are good to go using that method.

03-02-2012, 07:55 AM
A board clamped to the sheet, and a jigsaw with a fine tooth blade works well. The skilsaw with a backwards blade does not. A skilsaw with an abrasive blade works OK for metal, but is pure hell even with ear muffs and foam plugs. I bet a plasma cutter would work well.....

03-02-2012, 03:54 PM
A diamond coated blade in an angle grinder is my preferred power cutting option. Screws are preferable to nails for fastening in my view.

03-02-2012, 05:17 PM
Yeah.... The neoprene grommeted screws are worth the stupid price. I think I had them worked out at a nickle apiece..... And the guys I had "helping" me kept dropping them. "Why are you picking those up? Costs you more to pick em up than it does to buy more" they said...... Then I told them that the damned screws cost more than they were making on the job..... They still dropped them but they stopped complaining.... :D

03-02-2012, 05:27 PM
I'll try the blade in the grinder as I have a couple of long runs to cut on top of the crosscuts.

Somehow I ended up with hex drive screws so I'm good to go there . . . along with the foam strips you mentioned before.

Thanks for the tips, Grant.

03-03-2012, 12:09 PM
Since you'll be putting the screws into the ridges (not in the valleys) you have to be very careful about tightening them up. You want the gasket snug but not so snug as to pull a big dimple into the ridge. You might be able to get consistent tension by playing with the drive settings or you could put them 95% in with the power driver then finish up by hand.

Phil Y
03-03-2012, 03:54 PM
I like that honeycombe panel

Nicholas Carey
03-03-2012, 04:31 PM
I like that honeycombe panel

One of the nice things about it is that it can be bent along the grain, even the thick panels like 25mm



03-25-2012, 04:59 AM
I was determined to have this done before Pless started on his bathroom again. |:) Looks like I made it. Actually, I would have been done sooner but I took time to repair and paint the areas that would hard to reach after the panels were applied.

All the great suggestions came in handy and helped make this a fairly smooth and uneventful job. Tins snips worked great. To mark the cuts and scribes I used a grease pencil, which wiped right off after the cuts were made, and the factory edge of another sheet was good for making the marks square. On the panels where several had to be the same length I cut one and used the factory end of it to mark the others.

It turned out the shed and the framework were not exactly true and square to each other. Luckily I had a windless morning when I started fitting the panels and by taping the panels together at each end of the overlaps, I laid the whole front section of the roof out without fastening it. This allowed me to see how it would end out at the ends of the awning and scribe the panel (seen in the foreground of the first pic) that intersects the corner of the shed so it all lined up once it was fastened tight. This also showed me where things were askew and where I would need to trim or fudge things to get them at least looking straight.


And a few hundred trips up and down the ladder later . . .


Thanks again for all the great suggestions.

03-25-2012, 05:09 AM
Nice job!! But just going back to your first post here, since when did you Yanks start having such things as "blokey sheds"?

03-25-2012, 05:53 AM
We Yanks have probably always had them, by different names perhaps.

Since it's parked a few feet from an authentic Australian Hills Hoist . . . and my wife used to live In Aus . . . and I sometimes hide out in there when I've done something to cause her to spit the dummy . . . blokey shed only seems fitting.

Besides, it wouldn't qualify as a true man cave 'cuz there's no A/C, cable TV or beer fridge.

03-25-2012, 06:23 AM
Fair enough, that explains it then, no "blokey shed" would have A/C or cable TC, but you do need to do something about getting a beer fridge in there.