Incorrect end lap on a corrugated iron roof

There is a right way and a WRONG way to ‘end lap’ a corrugated iron roof

In the ‘old days’, metal roof sheeting came in stock lengths. There are many old metal corrugated roofs in Sydney with 6 foot (2.4m) long roof sheets end-lapped together along the length of the roof – to achieve the required total sheet length.

….And because end lapping of corrugated roof sheeting was so common back then, the old roofers knew how to install the roof sheeting so that the end laps did not leak.

Nowadays, roof sheeting is available to any custom length. So your roofer will measure your roof and order the roof sheeting in single lengths. There are no end laps and one less place for leaks and corrosion to start.

However, if the roof is very long or if access is difficult, roofers in Sydney will still be forced to install metal roofs with end laps. So a long roof may have one or two end laps in it.

If the end laps are done correctly, it will produce a very serviceable roof. But end lap skills have disappeared a bit and many modern-day Sydney roofers may find it difficult to install an end lap correctly.

Recently, I was called out to a leaking metal skillion roof in the inner west of Sydney. The roof was large and long and it had two end laps on it. There were no corrosion problems and apart from being laid a bit ‘flat’, there were no easily observable reasons why the roof was leaking.

Upon further probing, I finally discovered that some of the end laps were installed incorrectly (funny enough, most of the other end laps were done right).

…So, how can an end lap on a corrugated roof be installed incorrectly and why does it make it leak?

Check out the video below to find out….

0 0 votes
Article Rating
Notify of
Newest Most Voted
Inline Feedbacks
View all comments
Michael Yee Joy
Michael Yee Joy
9 years ago

Hi Jack
I am very impressed with your website and the knowledge you have about many aspects of roofing the solutions to roofing problems
I have a problem with a roof over a large deck. The slope of the roof is about 3-4 degrees and I have Bluescope trim deck . I had the roof pitch increased as an engineer said we should have used cliplock. The ceiling is mouldy and the plumber/roofer says that we used the wrong paint. I had the ends turned up at the higher end of the roof. The roof still leaks and we have a box gutter as water from the deck roof and the house flows into the gutter.
I need your help.
Best regards

9 years ago


Leaks on metal roofs can be quite hard to track down- especially if you have a box gutter attached and the roof is quite flat,

As always, a site inspection is needed to see if a solution can be found – so that the roof leak can be repaired.

9 years ago

Ηеy thеre! Someone іn mу Myspаce group shaгed
this website with us ѕo Ӏ cаme tο
give it a loοk. I’m definitely loving the information. I’m boоkmаrking and will be twеeting this
to my follοwerѕ! Great blοg and exсellent dеsign аnd stylе.

My homepage … oklahoma city roofing company