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Roofing question -- new skylight

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  • Mar 21st, 2019 12:39 am
[OP]
Deal Addict
Aug 21, 2007
1921 posts
1077 upvotes
Vancouver

Roofing question -- new skylight

Hello All,

Our roof is at the end of its life and we had a roofer come out to give a cost estimate. We asked them for advice about installing a new skylight over our living room, whether we should do the roof and skylight all at the same time (we're not 100% committed to it as we're not sure if we have the budget immediately available). The roofer said they could do the outside work but they don't do the inside, and that we could do the inside work years after doing the outside. Is this a good idea? Isn't it usually better to do both the outside and inside work at the same time? Don't you usually start installing the skylight from the inside out? Are there any obvious pitfalls we should be mindful of?
9 replies
Deal Addict
Jan 28, 2007
2123 posts
1441 upvotes
SW Ontario
Depends on how your roof and ceilings are design wise.

What the roofer is referring to, is mounting the skylight into the roof when he is doing the reset of the roof so that it is water proof and flashed properly all at once.

The skylight would be just looking into the attic space until such time as you cut a hole in your interior ceiling and build the light tunnel into the room.

Depending on skylight size, the number being installed and roof framing, it shouldnt be terribly expensive to finish the inside.

I have skylights and done some of the interior work myself over the years
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Deal Expert
Aug 2, 2001
15930 posts
6116 upvotes
If you are getting a skylight installed it would be best to have the exterior portion done at the same time as the rest of your roof. It will allow all the water proofing to tie in nicely. You would not want a roofing company doing the interior part of your skylight - they are roofers and do not do finish work inside a home (and some would argue just do "rough" work on the outside).

Now why I would want the interior to be done first is simple. You likely have a specific spot in your house you want the skylight. Let's say over your bath tub. If you do the roof portion first what are the odds that the skylight will line up perfect with the spot you want? If they are off a bit the skylight is now over your toilet instead. Where as if you do the interior and such first you just cut out the skylight in the exact spot you want. Roofers are not finish carpenters who make an artistic masterpiece that has tolerance of even an inch. Roofers are skilled at what they do - but their work has much tolerance involved and is not meant to be precise. Therefore I would not leave it to them to line up the right spot for the skylight, but rather have it to you can show them where to do it.

If you are not wanting a specific spot and can be tolerant of where they place it then it's fine to do it now. My only concern would be if you have a very specific spot you want it they may not be able to accommodate without the interior work being done first to show they the right spot.
Deal Addict
Jan 28, 2007
2123 posts
1441 upvotes
SW Ontario
TrevorK wrote:
Mar 17th, 2019 2:49 pm
If you are getting a skylight installed it would be best to have the exterior portion done at the same time as the rest of your roof. It will allow all the water proofing to tie in nicely. You would not want a roofing company doing the interior part of your skylight - they are roofers and do not do finish work inside a home (and some would argue just do "rough" work on the outside).

Now why I would want the interior to be done first is simple. You likely have a specific spot in your house you want the skylight. Let's say over your bath tub. If you do the roof portion first what are the odds that the skylight will line up perfect with the spot you want? If they are off a bit the skylight is now over your toilet instead. Where as if you do the interior and such first you just cut out the skylight in the exact spot you want. Roofers are not finish carpenters who make an artistic masterpiece that has tolerance of even an inch. Roofers are skilled at what they do - but their work has much tolerance involved and is not meant to be precise. Therefore I would not leave it to them to line up the right spot for the skylight, but rather have it to you can show them where to do it.

If you are not wanting a specific spot and can be tolerant of where they place it then it's fine to do it now. My only concern would be if you have a very specific spot you want it they may not be able to accommodate without the interior work being done first to show they the right spot.
The problem is that your generally limited to placing a skylight based on where your roof trusses are located. Skylights and light tunnels are fitted between the trusses, limiting where your able to position it from inside.

In some cases, roof trusses can be cut and modified, however, that can get expensive as your going to need to have someone sign off on the structural changes engineering wise. Improperly modified trusses can lead to all sorts of roof issues.
I'd rather be outdoors camping, kayaking, and mountain biking ...
Deal Expert
Aug 2, 2001
15930 posts
6116 upvotes
Jojo_Madman wrote:
Mar 17th, 2019 3:03 pm
The problem is that your generally limited to placing a skylight based on where your roof trusses are located. Skylights and light tunnels are fitted between the trusses, limiting where your able to position it from inside.

In some cases, roof trusses can be cut and modified, however, that can get expensive as your going to need to have someone sign off on the structural changes engineering wise. Improperly modified trusses can lead to all sorts of roof issues.
In the example of a bath tub you place the skylight within your trusses but a couple feet "up" or "down" on the roof could mean a skylight that's not even completely in your bathroom. If you don't care exactly where inside it is, then building it from the exterior can be fine. But you have lower tolerance for placement (e.g. 1-2 feet) doing it from the exterior and trusting the measurements to be right seems like a poor idea.
Deal Addict
Jan 28, 2007
2123 posts
1441 upvotes
SW Ontario
You might also want to consider a skylight you can open as well. The next time we need to replace the one at the top of our stair well (house is open concept) I will be going with one that opens. There have been numerous times in which simply being able to open it would help vent heat out or let air in.

Just make sure whomever installs it, does a thorough job insulating the walls of the skylight well, as I've seen a number of them done poorly
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Deal Addict
Jun 26, 2009
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GTA
Skylights always leak. Always.
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Sep 8, 2007
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Way Out of GTA
Tommy74 wrote:
Mar 20th, 2019 8:52 pm
Skylights always leak. Always.
Yep. By installing one, it introduces a bunch of issues and potential problems down the road. I avoid them whenever possible.
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Jan 28, 2007
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Tommy74 wrote:
Mar 20th, 2019 8:52 pm
Skylights always leak. Always.
If they are done properly and if they are Velux ... they never leak ever after 20 years. Only replaced them when the egas seal let go and it was condensating.

One of the reasons Velux is the only skylight I specify and recommend ...
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Deal Fanatic
Jan 25, 2007
6742 posts
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Paris
Tommy74 wrote:
Mar 20th, 2019 8:52 pm
Skylights always leak. Always.
Ive rarely seen one put in correctly. When I sold them briefly people were willing to pay for their skylight with electric blinds inside that opened automatically but they rarely if never paid for the proper mounting kit for their install.

And in some cases, I understand why. Who wants to pay $500 for a metal roof mount for a $250 entry level skylight? So everyone (contractors included) builds their own mount for it out of flashing and caulking which lasts just long enough for the contractor warranty or the consumer to complain “it leaked after a few years”

Tube style skylights are great and cheap. I have one, recommended my brother one and would do one again myself. Very easy to DIY install too.
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