Roofing the shed

Printable View

24th March 2008, 11:24 AM
spruik

Roofing the shed

Using corrigated colorbond roof sheets, instructions tell me to start "lip up" about 25mm from end of perlin. On another website (different brand of shed) it tells the reader to start with "rib turned down". That website also says that if shed is over 7000 long, start with 40mm from end.

1. Is "rib" the same as "lip"?

2. So, how should we start, lip/rib up or down?

3. Why does that matter, if it does?

4. Why have a greater distance from end for a shed over 7000?

5. Why any distance at all, what's wrong with flush or maybe 5mm from end (less chance of water coming in)? In fact the sheets could finish over the side by up to 10mm (would need lip/rib up), barge capping appears to allow for that.

Hate to screw it up to find a major issue when finished...
24th March 2008, 11:51 AM
Barry_White

Spruik

When laying corrugated first of all you want to lay your sheets with lap facing away from the prevailing wind so you would start from the end away from the wind and you would lay the first sheet with the lip down so that the next sheet that you lay overlaps the first sheet.

Do they mean the end of the shed or the end of the roof sheet.

The reason that the distance from the edge can vary from the various manufacturers can be that is how they have calculated how your barge capping will fit without the turndown on the capping from sitting on the top of a rib of the roofing.

When it is from end of the sheet it could be just some other allowance.

Also when laying the sheets you need to check measure the distance every couple of sheets making sure you are keeping them parallel to the end of the shed because when you are walking on the sheets they tend to creep.

It is best to first only screw the laps on each purlin and then go back and put the rest of your screws in after you have the whole roof laid.
24th March 2008, 02:51 PM
spruik

Bazza,

Wind is always a bit of a problem here, it might be just fine for hours and then you'll get a sudden strong gust.

The end means end of perlin (end of shed - outside wall). I can't see any need for a space from the end, there is nothing that would create an issue. Ridge cap is straight forward and barge capping would need to be fitted carefully at the top so that no water will come in. Leaving a space looks like inviting the rain inside.

Think I will overlap (past the end of the wall) by 10mm, barge caps allow for 15mm and the wall will be 5mm outside the end of the wall due to my fancy formgirt. Also, if I don't stretch them in the process of laying, it will finish nicely at the other end in the same way.

I have 2 skylights on each side of the roof and they are very light, so I'll lay them on top of the steel roof sheets both sides. Don't think they should be walked on at any time.

I intend to secure them with just the minimum number of screws until they are all on and fit correctly. I am aware of keeping them square.
24th March 2008, 04:46 PM
munruben

Sounds like you have already decided how you are going to tackle the task.
24th March 2008, 07:08 PM
Barry_White

Quote:

Originally Posted by spruik

Bazza,

Wind is always a bit of a problem here, it might be just fine for hours and then you'll get a sudden strong gust.

The end means end of perlin (end of shed - outside wall). I can't see any need for a space from the end, there is nothing that would create an issue. Ridge cap is straight forward and barge capping would need to be fitted carefully at the top so that no water will come in. Leaving a space looks like inviting the rain inside.That should be fine and just remember the last sheet will finish with the turned up edge.

Think I will overlap (past the end of the wall) by 10mm, barge caps allow for 15mm and the wall will be 5mm outside the end of the wall due to my fancy formgirt. Also, if I don't stretch them in the process of laying, it will finish nicely at the other end in the same way.

I have 2 skylights on each side of the roof and they are very light, so I'll lay them on top of the steel roof sheets both sides. Don't think they should be walked on at any time. That is the correct way to lay the skylights both edges overlapping. You should really have safety mesh under the skylights just in case kids happen to get on the roof and walk on the skylights.

I intend to secure them with just the minimum number of screws until they are all on and fit correctly. I am aware of keeping them square.

Just my humble opinion.
25th March 2008, 10:03 AM
Vernonv

I would stick with what your instructions say.

The problem is that the turned down lip on the barge capping has been calculated to sit in the corrugation valley (at both the start and end of the roof sheets). If you change the position of the valley, you may end up with this lip sitting on the top of a peak.

You could/will? also end up with a bigger gap at the other end of the roof.

I'm sure the people you bought the shed from (I'm assuming you purchased and are installing a kit shed) have put that dimension in there for a reason and not just for the "fun of it".
26th March 2008, 02:32 PM
spruik

Quote:

Originally Posted by Vernonv

I would stick with what your instructions say.

The problem is that the turned down lip on the barge capping has been calculated to sit in the corrugation valley (at both the start and end of the roof sheets). If you change the position of the valley, you may end up with this lip sitting on the top of a peak.

You could/will? also end up with a bigger gap at the other end of the roof.

I'm sure the people you bought the shed from (I'm assuming you purchased and are installing a kit shed) have put that dimension in there for a reason and not just for the "fun of it".

vernonv,

Instructions are ambiguous at best, or non-existent.

If I follow their instruction to start "lip up", 25mm from end of perlin, the lip down of the barge capping sits exactly on top of the peak of the corrugation. I now fixed the first sheet with "lip up" overhanging the end of the wall by 10mm, and the barge cap will end above the valley of the first sheet.

No gap at other end, worked that out, will end with lip up - also overhanging by 10mm.

Would be helpful if instructions come with some sort of explanation or stating reasons why. Always works better when the operator know why to do things a certain way.
26th March 2008, 02:44 PM
Vernonv

Quote:

Originally Posted by spruik

Would be helpful if instructions come with some sort of explanation or stating reasons why. Always works better when the operator know why to do things a certain way.

Yes, especially when the instructions are wrong.

I'm sure you are doing this, but I'll ask anyway - You are checking the fit of the barge capping and roof with wall sheets on?

Well anyway, it sounds like you have worked out the best way to achieve a neat result.
26th March 2008, 04:14 PM
Barry_White

Quote:

Originally Posted by spruik

vernonv,

Instructions are ambiguous at best, or non-existent.

If I follow their instruction to start "lip up", 25mm from end of perlin, the lip down of the barge capping sits exactly on top of the peak of the corrugation. I now fixed the first sheet with "lip up" overhanging the end of the wall by 10mm, and the barge cap will end above the valley of the first sheet.

No gap at other end, worked that out, will end with lip up - also overhanging by 10mm.

Would be helpful if instructions come with some sort of explanation or stating reasons why. Always works better when the operator know why to do things a certain way.

Spruik

By the sounds of things if you started with the lip up you are either lifting the sheet to overlap the next sheet or you have turned the next sheet around to overlap or you are laying all the sheets with the lip up on top all the sheets facing your starting end. If that is the case you have got it all wrong and have eliminated the anti capillary recess under the sheet that is designed to run the wind driven rain water away from going under the sheets.

If you think I don't know what I am talking about I spent eleven years with BlueScope Lysaght as a manager and rep advising builders etc the correct way of doing things and three and a half years selling and building sheds.

But then you may have read my disclaimer in my signature and if you have done it your way why did you ask the question in the first place.

Then there are shed manufactures that give detailed information and others that give none.
26th March 2008, 07:45 PM
spruik

Quote:

Originally Posted by Vernonv

Yes, especially when the instructions are wrong.

I'm sure you are doing this, but I'll ask anyway - You are checking the fit of the barge capping and roof with wall sheets on?

Well anyway, it sounds like you have worked out the best way to achieve a neat result.

Actually I forgot about the 10mm ribs in the wall sheets, but it still will work out nicely. The barge capping lip will entirely cover the sheet ridge and finish up just before the deepest point of the valley.

Have to do the slab before the wall sheets can go up. Wrong way round of course, but the structure won't go anywhere soon - it's very sturdy and have braced the wall with 2 wire ropes diagonally.

Won't use formgirt for my next farm shed, too fiddly and time consuming. And far too expensive for a 6 bay farm shed (4 roller doors). This shed is a learning process for me.
26th March 2008, 08:51 PM
spruik

Quote:

Originally Posted by Barry_White

Spruik

By the sounds of things if you started with the lip up you are either lifting the sheet to overlap the next sheet or you have turned the next sheet around to overlap or you are laying all the sheets with the lip up on top all the sheets facing your starting end. If that is the case you have got it all wrong and have eliminated the anti capillary recess under the sheet that is designed to run the wind driven rain water away from going under the sheets.

If you think I don't know what I am talking about I spent eleven years with BlueScope Lysaght as a manager and rep advising builders etc the correct way of doing things and three and a half years selling and building sheds.

But then you may have read my disclaimer in my signature and if you have done it your way why did you ask the question in the first place.

Then there are shed manufactures that give detailed information and others that give none.

Bazza, I am learning from you.

Instructions only mention to have the wind in your back when putting them on. But I don't do anything when it is windy.

It says to start with lip up, so I must assume they expect the operator to lift each sheet up and fit the next one underneath. In fact it says to underlap sheets approx 85mm. But if 85mm was applied, the sheets wouldn't fit properly at all.

I did give thought as to the way adjoining sheets should fit. I figured that the side with the lip down should overlap the adjacent sheet, in order to minimise rain from entering or accumulating between the sheets.

The first sheet is on the roof starting with lip up. Second sheet will be the skylight. The third steel sheet is turned around underlapping the skylight (skylight on top) and subsequent sheets will overlay with lips down until the skylight at the other end (one before the last).

To do things really well, with the skylight on top on both sides, the skylights should be trimmed on one side so that both sides have "lip down".