Minimum pitch for formed steel roofing sheets

[King Herald]

We plan to use 'Colorsteel' tile effect roof on our new house in the Philippines. The roofer wants to do one area almost flat, but I am pretty damn sure that any of those overlapping type roof sheets have to have a minimum angle on them to stop them leaking.

I'm stuck out on a ship at the moment, so can't really ask anything of the manufacturers of this particular product, but has anybody got any experience with steel roofing of this type?

I really don't want some local 'craftsman' putting it on, then running tubes of silicon sealant hither and yon to stop it leaking...

http://colorsteel.com.ph/tile.html

[Steffan]

There are regulations and each manufacturer specifies the minimum pitch very clearly. If you identify the make and profile details I will find the relevant information. I enjoy the challenge.

But details of the profile form, manufacturers description and manufacturer are essential for a specific answer.

You are right in that an absolutely flat roof almost certainly will not comply and should therefore be questioned in detail.

But there are ultra low pitch systems with specific profiles.

Also in residential property steel roofs need very specific sound insulation as well as thermal insulation because they are like a drums skin in the rain which in the country you are suggesting could be a real challenge.

[King Herald]

Interesting point about the drumming on flat roof. During the monsoon we can have several inches of seriously hard rain in an hour or so. Even with a full pitched roof it sound like a handful of Phil Collins pounding on the roof in heavy rain.

The roof I beleive we will be having is simply referred to as Colorsteel Classic.

It appears to be manufactured in the Philippines, and also New Zealand. Whether it is the same product I can't determine.

The link I gave earlier is about all the info I can find on it.

[Steffan]

The manufacturer will be able to confirm the precise specifications and detail.

My knowledge of Phillipine building regs is minimal.

I would try the manufacturer or agent. I an sure this detail will be readily available in the country of use. Sorry I cannot be of more help.

[King Herald]

Steffan said:

The manufacturer will be able to confirm the precise specifications and detail.

My knowledge of Phillipine building regs is minimal.

I would try the manufacturer or agent. I an sure this detail will be readily available in the country of use. Sorry I cannot be of more help.

No worries. I've e mailed the manufacturers asking about the minimum pitch, but the reply will probably be something along the lines of "Oh yes, you can use this roof at an angle....".

[roofer]

I wouldn't use that at less than 22 degrees. And definately not flat. Its basically a cheap metal profile roof.

We fit a lot of this (never flat) enough guides to show you how metal sheet should be installed.

http://www.decra.co.uk/Download/Video/Video_Instal...

[King Herald]

roofer said:

I wouldn't use that at less than 22 degrees.

Yes, that is the sort of angle I was imagining.

Is there any other way to do a flat roof, or nearly flat, in steel or similar? There is just a 3m x 3m area that the design needs to be flat if possible. If the contractor had said months ago that it could not be done, then we'd have found another way to get the design/roof profile we want, but he didn't....

I'm on the slowest internet connection in the world out here, so no chance to download the video, sorry.

[caziques]

http://www.nzsteel.co.nz/files/Installers_Guide_op...

At 1.47mB maybe a bit big for you.

WATER PONDING
Roofs
Where the roof pitch is low, changes in roof loadings may result in a negative pitch and consequently
lead to water ponding. Water ponding is detrimental to the performance of COLORSTEEL®
prepainted steel products. The following conditions commonly cause water ponding:
• Over-spaced purlins.
• Deformation of timber purlins.
• Placement of external loads such as air conditioning units.
• Rigid fixing on long spans which causes deformation of the profile as a result of
thermal expansion.
Design Guide:
1. Never use a pitch of less than 3 degrees. Pitches of less than 3 degrees invalidate
the warranty.
2. Design the roof according to the profile manufacturer’s specifications.
3. On minimum pitch roofs, ensure that the gutter end of profiled sheets is turned down.
4. Allow for thermal expansion to prevent profile distortion.
5. Consider the use of walkways to prevent damage where the roof may be subject to heavy
foot traffic.
6. Ensure roof penetrations do not block the flow of water from the roof

Colour steel is popular in NZ, the fitting angles here can be to do with snow loadings. With a very low pitch could you use it without the tile effect?

As above 3 degrees is OK if you don't have any joins that run across the roof. (Capillary action etc).

My roof is coloursteel, wonderful sound in heavy rain!

[King Herald]

Thanks for that. 3 degrees sounds awfully flat. I saw it mentioned on their website but was thinking it might mean 3 degrees above the minimum pitch. But it sounds not.

The material itself might not leak, but I'd be worried about the extreme edges. Torrential monsoon rain, a strong wind in the wrong direction, and water will puddle and blow around until it overflows the point where the sides and top end join the rest of the roof structure.

[CedGTV]

I've not used this type of metal roofing before but have used a Double Six corrugated sheeting on a warehouse roof (On the trading estate just to the side of Staples Corner after the IRA bomb went off years ago.) The angle of the sheets was getting on for about 25 degrees and we used a triple bead of a roofing mastic (It came pre extruded on a building paper that was removed when the beads were laid on the upper side of the lower sheet)this was then laid across the sheet and down the leading edge for our seal.

This only really tells you that it is possible to seal flat-ish profiles but with the types of weather pattens you have out there the taller the pitch the better. IMHO.

[King Herald]

I can imagine the sheets themselves can be sealed together quite well, but it is the corners that worry me.

Just to show the situation, here is a rough idea what we want, and what has been planned from the start, but now we are told it can't be done.....



Now we've been told it needs to angle down towards the rear, which in turn involves having a gutter along the back as well as all the other sides. And makes the back wall too low to fit a door in........

[roofer]

King Herald said:

Yes, that is the sort of angle I was imagining.

Is there any other way to do a flat roof, or nearly flat, in steel or similar? There is just a 3m x 3m area that the design needs to be flat if possible. If the contractor had said months ago that it could not be done, then we'd have found another way to get the design/roof profile we want, but he didn't....

I'm on the slowest internet connection in the world out here, so no chance to download the video, sorry.

Standing seam or lead with hip rolls.

[King Herald]

roofer said:

Standing seam or lead with hip rolls.

If I knew what that terminology meant I'd already have the answer to the problem.

[Henry-F]

We have used quite a lot of Kingspan on our property here in the UK and I swear by it. Rather than being simply a steel roof it is constructed as a sandwich of the outer steel sheet bonded to a rigid expanded foam core which is in turn bonded to an inner finishing steel panel. The core serves several purposes including insulation, sound deadening and structural rigidity. It is super quick to install and whilst obviously in the UK at least geared to industrial buildings it does have the potential to be used on domestic properties.

I haven't googled your particular sheeting but I wouldn't use anything but an insulated panel. As a guide the insulation ranges from around 50-100mm.

Good luck

Henry

[King Herald]

Henry-F said:

We have used quite a lot of Kingspan on our property here in the UK and I swear by it. Rather than being simply a steel roof it is constructed as a sandwich of the outer steel sheet bonded to a rigid expanded foam core which is in turn bonded to an inner finishing steel panel. The core serves several purposes including insulation, sound deadening and structural rigidity. It is super quick to install and whilst obviously in the UK at least geared to industrial buildings it does have the potential to be used on domestic properties.

I haven't googled your particular sheeting but I wouldn't use anything but an insulated panel. As a guide the insulation ranges from around 50-100mm.

Good luck

Henry

Unfortunatly, over here they seem to have the notion that you only use insulation in cold countries. I doubt any sort of insulated roofing will be available, but I'll have a look around for the Kingspan stuff. We are pretty much restricted to what the contractor building the house will use, but it is all open to negotiation, if money is laid on the table.

They use that 1/2" thick silver/foam sheet under the roofs normally, but I have serious doubts about its effectiveness.

We also originally wanted UK style UPVC windows, but people told me they don't have them here. Anyway, I recently found some in a local builders merchants, with limited size option. And now I hear they also make them to order. Far better than the usual aluminium sliding window monstrosities used over here.

[roofer]

King Herald said:

If I knew what that terminology meant I'd already have the answer to the problem.

Kingspan Composite for zero falls is their new Topdeck which is membrane/metal. Uber expensive.

[King Herald]

Hmmm, lead sheet. That would last about a week and some toerag would be up there stealing it. They stole the petrol engine off the concrete mixer last Sunday apparently, just unbolted it in the middle of the night and walked away.

I wonder if they could do something similar with galvanised steel sheet? That is more practicable where I live. Maybe 3m x 3m+ is a bit big though.

[roofer]

If you have a Zinc supply out there, zero falls can be achieved. The easiest way from cost point of view is ply deck and torch on membranes. Not sure on skills level out there though.

[King Herald]

roofer said:

If you have a Zinc supply out there, zero falls can be achieved. The easiest way from cost point of view is ply deck and torch on membranes. Not sure on skills level out there though.

Zinc coated sheet is readily available, in various thickness, but I'm not sure the largest size sheets. Maybe it comes in rolls, 4 foot wide and as long as you want.

I was thinking along the lines of a felt-type melted-on covering. I'll have to check and see what is available. We had it on the roof of our flat garage in the UK, and it lasted well enough. Not sure how it would take to the searing hot sun ten months a year though.

These guys can be pretty skilful, but you have to make really sure you get the one who can do the job, not the one who just talks a good job.