Replacing A Leaky Skylight

I am a homeowner in central NJ. I have a Velux VS-1 skylight in a bedroom cathedral ceiling that was installed in the late 1980’s that has had a slow leak in the head flashing area (a few drops during heavy
rain) on and off for most of its life. I have had a piece of plywood on top of the skylight for awhile and that seemed to stop the leak, but now even with the plywood, the leak has become worse. I would like to replace it with a Velux fixed FS-304 because the rough opening is very close to that of the VS-1.

The roofing material is the standard 3 tab shingles and the pitch is 3/12. If I can use the FS-304 skylight with the standard EDL flashing I may tackle this job myself, however, if it requires special flashing, I’m in over my head. The existing skylight was installed by a general contractor when he built the 13 x 12 bedroom addition, and it appears to have been done correctly with sill, head and step flashing, but I’m not so sure that a special curb or flashing was required. The last thing I want is for the new skylight to leak.
Some pictures follow.

Any advise is appreciated.
Dennis B.

That particular skylight tends to leak.

The fixed Velux you are replacing it with is much better.

There is a flashing kit that goes with the skylight you are going to purchase.
It is a separate item…

The shingles are going to be very brittle so much care must be taken when tieing it all in.
Get some Grace Ice & Water shield, wrap the frame of the skylight with it.

You may want to get a roofer to do this…

yes, the new skylight should come with all new flashing.
Velux skylights have excellent flashing.
I recommend you call an experienced roofer to do this.

I would consider getting a velux accessory that allows the skylight glass surface to have a better pitch
that the one that matches the roof. That skylight reminds me of a guy in new boots standing in a bathtub, while it is filling up…eventually, the water will go over the top.
try this link … efault.htm

hope this helps


[quote=“Z car Fan”]yes, the new skylight should come with all new flashing.
Velux skylights have excellent flashing.
I recommend you call an experienced roofer to do this.[/quote]

Unless you get one of the new fangled rubber skirted thingys, the flashing kit is separate and extra.
Don’t get the new fangled rubber skirted type of skylight…

Velux makes the best skylight in the business, skylights that open are frequently a problem regardless of manufacturer.

You’re likely to have a lot of wood deterioration in the area around that skylight. That’s probably why it leaks now despite the additional cover.

One of the problems you are going to encounter is that you have a low slope leading to a wide catchment (upper edge of skylight). The perimeter of the skylight should have a full width of I&W applied (and flashed to the skylight) to avoid leaks.

There is a saying that “skylights leak, period”. They don’t have to. Some setups are harder to install in a completely watertight manner than others, but with attention to detail, they can be leak free for the life of the roof and/or skylight.

I would replace roofing shingles in that area ice and
water all around and up frame. Never had a velux leak
they are worth every cent.

I agree with everyone, Velux is an excellent skylight.

It’s great when you are able to do a project on your own and save some money, but I’m not sure I would recommend doing this particular project on your own because of the low pitch and likelihood of rotted roof decking.

I spent about 15 minutes just now trying to type the step by step method I personally use to replace a skylight.
There are a lot of little details that are hard for me to explain in writing. These details (in my opinion) are critical to the prevention of leaks.
It’s just to hard (for me) to explain without acualy showing you exactly what I’m talking about… so I will simply say “Hire a professional”.
You’ll pay extra, but it’s worth every penny spent.

Thanks to all for your advice. Can you give me an idea what a professional would charge for this job. Does the roofer typically obtain the skylight or the homeowner? Thanks again.


I would concern myself with the roof edge / drip edge detail on the area above the roof cheek where there seems to be a Rake board missing, most likely sided over during installation, most often when existing siding is NOT removed, and / or 3/4 styrofoam is applied under new siding. I prefer that the homeowner
purchase/ pay for/ and arrange delivery for
special items like skylights, doors and windows.
That way, all warranty issues are directly dealt with for them, by them, and they have original receipts in hand to refute manufacturing issues.

i’d reshingle the whole area for the trouble it should be easy to do since its a 3/12 however when you use the velux flashing kit remember on the head flash to use the extra piece they give you or the head won’t fit tight alot of ppl miss this step and wonder why it doens’t sit right u’ll see it with the kit its a little spacer you could say more or less but it comes with the kit

You need to call several roofers.
Do not choose based on price or skin color or how long they say they have been in business.
Choose by their character, detail, honesty, knowledge.

You can call and just ask for skylight replacement if you like.
But when the “roofer” gets there, he should ask you how old your roof is. When you respond with Late 80s
It should be a closed case–replacement of entire addition roof. If the steeper roof is of the same age
then replacement of entire roof.

No respectful roofer should be replacing a skylight and warranty it on a 20 year old shingle roof.
That’s crazy.

I also do not believe that is a 3/12.
If and when confirmed, i would be replacing with a flat roofing product and a curb mount skylight.
I would build my own wooden box.
Cant strip around it, run all roofing material to the top of my wooden box and cap it with my skylight.

Any roofer that comes up and doesn’t repeat what i said word for word-- throw em off the roof :smiley:

If you dont like what i have said,
NO problem, you will easily find most roofers to tell you what you want to hear.

There is one layer of shingles on the entire roof. If they were to reshingle just the roof on the addition, should that layer be taken off?

If it were my house, i would strip it,
because I would be concerned that the constantly leaking skylight has caused the sheathing to rot.
Better to be safe than sorry, and it makes the skylight/ membrane installation less complicated.

My $.02


You wanted some heads-up on prices
Here it is.
Replace the whole roof. It’s much cheaper.

example- I would charge around 3500 to replace the low-slope roof and tie-in to the existing.

Or i could charge you 5500 to do the whole roof.
I would insist on nice architects for your steeper roof.

lets say you only want the 3500 dollar job.
Then two years later your steeper roof needs replaced and i am still going to want another 3500-4000 dollars.

Your prices there could be less expensive ,
but the way a contractor wants to be paid will be structured the same.

Put some gorgeous Architects on that roof, border it with the right color evemetal (not white) and it will make your place look 10 times better.

Whats best for YOU and your roof is that you dont spend a dime on patching that roof. Replace the entire roof now. Keep that power vent or replace it if it is broken.

Yes thebaycompany, you have right. The new Velux- skylight is the better option.

That is a low sloped roof,Hello. Strip the whole thing and apply full coverage I&W,wrap the curb of the skylight and have the roof and flashing kit installed by a roofer.Its important to check the pitch, the lowest you could really go with that type of skylight is a 3 in 12 and thats pushing it. any lower and it should be considered a flat roof and have a membrane roof and flat roof style kit or you could always build your own. Never shingle a flat or almost flat roof.

Stevie Wonder could see that is a 4/12…lol. Strip the shingles(whole house)I&W the entire area,and skylight frame,and bottom 6FT. Add ridge vent, and you will have no problem… I would wager to say that the roof deck around the original skylight is shot…(in my professional opinion)…

You can stick your sarcasim up your ASS Woolfboy. My point is that low pitch roofs being handled poorly are a major problem in the roofing industry.a 4 pitch should be full I&W sheild if it is a three it is flat. the other problem is the glazing on the shylight will fail if its not on an angled flat roof style built up wodden curb. these curbs can be flashed with shingles and step flashing as well.
I am speaking in general terms as opposed to this particular project.

that roof is barely even a 3 pitch…

Stevie Wonder