Skylight installation - InspectionNews

Jeff Eastman · #1 (**permalink**) 12-03-2007, 02:58 PM

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Scott Patterson · #2 (**permalink**) 12-03-2007, 03:54 PM

Quote:

Originally Posted by Jeff Eastman

Roofer says this installation is wrong but I'm not seeing it. I didn't write up any defects on it. Do you see something I'm not??

A couple of common things with skylights;
If it is over 30" in width it needs a cricket
If the slope is 3/12 or less pitch it needs a 4" curb or more

Also on the bottom edge the flashing should be on top of the shingles, not under them. I could not tell in your picture.

Matt Fellman · #3 (**permalink**) 12-05-2007, 11:10 PM

Ah yes, skylights..... I've paid out a few bucks on them before. The real stinger is that you can't always see an improper install in a visual inspection.

I actually had one in my own house about a year after I had the roof replaced. After it was torn apart you could see that the upper 'L' flashing was snipped a bit too far at the crease and it led to a leak. I was surprised how small of an imperfection led to a leak.

And I know.... I probably didn't have to pay for the one I did but sometimes it's just easier.

As for the one in the picture, I don't see the problem either.

Rick Cantrell · #4 (**permalink**) 12-06-2007, 05:33 AM

Scott
Of course you are correct in saying a cricket is needed if the skylight is => 30". I know it is not our job to design a repair, only to report that a repair is needed, but how would / could one make a cricket for a skylight?

Jerry Peck · #5 (**permalink**) 12-06-2007, 06:56 AM

Quote:

Originally Posted by Scott Patterson

A couple of common things with skylights;
If it is over 30" in width it needs a cricket.

Quote:

Originally Posted by Rick Cantrell

Scott
Of course you are correct in saying a cricket is needed if the skylight is => 30".

I've been trying to wrap mu mind around that ... where does it state a skylight wider than 30" needs a cricket?

A skylight is different than a chimney or wall in that the wider a chimney or wall gets, the more water which will build-up and collect on the high side of it, however, with a skylight, before the water builds up to a point where it could overflow its flashing (the reason for the cricket) the water would overflow the skylight itself because the skylight is not that high.

Unless I am missing something.

Scott Patterson · #6 (**permalink**) 12-06-2007, 07:15 AM

Quote:

Originally Posted by Jerry Peck

I've been trying to wrap mu mind around that ... where does it state a skylight wider than 30" needs a cricket?

A skylight is different than a chimney or wall in that the wider a chimney or wall gets, the more water which will build-up and collect on the high side of it, however, with a skylight, before the water builds up to a point where it could overflow its flashing (the reason for the cricket) the water would overflow the skylight itself because the skylight is not that high.

Unless I am missing something.

Well, I think that I should have said that anything that forms a penetration in a roof that is >30" should have a cricket. Chimney, skylight, ect. This is to keep the water from overflowing the flashing, just as Jerry pointed out. Most of the skylights that I have seen that are big enough to have a cricket are on commercial projects and the cricket is built into the flashing on the high side of the unit.

Rick Cantrell · #7 (**permalink**) 12-06-2007, 07:58 AM

Jerry
My first thought was that a cricket did not apply to skylights. So I looked it up in the 2006 IRC
" R905.2.8.3 Crickets and saddles. A cricket or saddle

shall be installed on the ridge side of any chimney or penetration
more than 30 inches (762 mm) wide as measured
perpendicular to the slope..."

Now, how to build a cricket for a skylight?

Jim Luttrall · #8 (**permalink**) 12-06-2007, 10:18 AM

Notice it is only required if perpendicular to the slope.

BARRY ADAIR · #9 (**permalink**) 12-06-2007, 10:26 AM

Quote:

Originally Posted by Jim Luttrall

Notice it is only required if perpendicular to the slope.

The only ones that arent perpendicular are the round models...or did I miss something, again?

Perpendicular - Wikipedia, the free encyclopedia

AB=downward slope of the roof plane CD=skylight head flashing in the wiki example

Eric Barker · #10 (**permalink**) 12-06-2007, 10:36 AM

Thanks Scott!

You've presented a whole new thought process to tax the aging brain cells. I never have given consideration to a skylight cricket and have never seen one that I can remember. Now with Rick's IRC post I'm in overload.

No more for today ok?

Jim Luttrall · #11 (**permalink**) 12-06-2007, 11:28 AM

Quote:

The only ones that aren't perpendicular are the round models...or did I miss something, again?

Com'on Badir, think outside the box.

Is a square skylight a just a square or a could it be a diamond shape??
How many chimneys have you seen that are on a diagonal in relationship to the roof plane?

Michael Thomas · #12 (**permalink**) 12-06-2007, 11:49 AM

The Velox installation instructions for both non-self-flashing and self-flashing skylights make no mention of crickets at any width or orientation.

Jerry Peck · #13 (**permalink**) 12-06-2007, 04:49 PM

Looks like what I was missing was the "or penetration".

Scott Patterson · #14 (**permalink**) 12-06-2007, 06:31 PM

Quote:

Originally Posted by Michael Thomas

The Velox installation instructions for both non-self-flashing and self-flashing skylights make no mention of crickets at any width or orientation.

Most that you will see for residential use will be smaller than 30", so it is not an issue.

Richard Rushing · #15 (**permalink**) 12-06-2007, 10:20 PM

From what I can tell from the photo, the bottom flashing of the skylight should NOT be under the singles. As is, the water running down the side channels allows for running up under the lower shingles.

Richard

Jim Luttrall · #16 (**permalink**) 12-06-2007, 10:42 PM

If you look closely, I think we can see the head of the skylight in both photos, if I am reading the lap of the shingles correctly.
If this is the case, then the "ears" of the flashing on each side form dams which would hold water at the head of the skylight rather than letting the water flow down and around the skylight. If the slope of the roof is shallow enough in relation to the height of the obstruction, then water could back up under the shingles or up and over the curb which looks a little short.

Rick Cantrell · #17 (**permalink**) 12-07-2007, 05:42 AM

sorry, I postet in the wrong thread

Jerry Peck · #18 (**permalink**) 12-17-2007, 06:33 PM

Quote:

Originally Posted by RobertSmith

Is the conclusion of this post that a cricket is needed? The code posted seems to indicate so "...or penetration more than 30 inches"....

Yes..

LR HOME SOLUTIONS · #19 (**permalink**) 10-13-2008, 07:47 AM

Skylights are my specialty. As a roofer and NOT an inspector. Over 20 years now in the trade

Ive seen them all, all types, all kinds, manufactured a few, repaired a few, fell through one or two....kidding..

Anyways....

Velux skylights are far the best on the market. Got that out of the way...

A cricket on a skylight. Maybe ? Never seen one. Either commercial or residential. However Ive not seen to many skylights over 30" Ive seen a few though and none of them ever had a cricket

It would make sense to add a cricket to the top side of the skylight greater than 30", but if the skylight is on a 4" curb? Your not going to gain to much of a slope to divert water away.

Curb mount skylights should be set on a 6" curb and NOT 4". Depending on location or climate conditions. Up North? Ice damns. Down South? Heavy tropical rains
Out west? Rains from every direction!

Water rushing down the roof would be less likely to get under 6"

There are a few tricks Ill share with you here in the forum

Weather Guard!!!
Weather Guard rain protector should be used around the entire skylight if you really want to make sure it wont leak. Wrapping the entire curb. 2.5 ft on the roof and .5 up the skylight curb. Corners wrapped just like you would wrap the metal flashings
With weather guard alone, your skylight is now watertight!

Roofers in general are very different from each other and installation practices from Washington DC to Florida and out to Texas are very different. Texas residential roofers being the worst Ive seen EVER!

If your skylight dont come with a pre-manufactured skylight kit Ie: Velux Flashing Kits

A roofer must make the curb flashings.

Pieces needed::
Top pan: Normally manufactured out of 24" .019 Aluminum or .24 galvanized coil stock (glavanize will rust over time) so Aluminum is preferred or copper. With copper you can sodder the corners

Step and counter flashings. Each side should ofcourse have step flashing per shingle or tile or...wood shake...slate...etc...

The bottom pan is nothing more than common apron flashings. Used to terminate a roof to the wall that is horizonal to the roof

With a 4" curb you should add a 1" return (philidelphia edge) to the top of the 4" side to stop water from rushing up under the curb mounted skylight.

A counter flashing should be used to cover the step flashings and yes, the bottom pan should be placed over the shingles and not under. However the reason some roofers do this over the metal method is to hide the flashings. Popular in northern states. I agree that this is a water trap and personally never install a shingle over the Apron flashings.

Ive got a detailed step by step on our website

Skylight Leaks | Skylight Repairs and Skylight Installations

Skylight repairs ?

Make sure you use Weather Guard!