# Velux skylight - deck mount vs curb mount?



## aribert (Apr 7, 2012)

Deck vs curb mount - Is one mounting configuration superior over another? IF so, please explain. I have installed a couple of Velux deck mounted skylights. It appears to me that one benefit of the curb mount is that the skylight as can be replaced with out any roofing work (not having to pull up shingles and weave in the step flashing for a new deck mount skylight) - *true?* 

I will be replacing two existing flanged mount skylights. One of these skylights is just under the edge of a large tree's crown. While the current acrylic bubble skylight has survived for 31 years; a couple of winters ago branch dropped straight down onto the soffit, punched a hole right thru the 1x T&G redwood decking. If a dropped branch were to destroy the skylight, I would like to be able to order a replacement skylight and mount it with out doing any roofing.

Finally, I was pricing the skylights and flashing kits at a local roofing supplier and the counter person stated that many of their customers (roofing contractors) do not tend to use the Velux flashing kit - instead the do the flashing similar to how one flashes around a chimney. My understanding is that the flashing kit is required to get the Velux warrentee (sp). Your thoughts?


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## Nealtw (Jun 22, 2017)

I have not seen one that has not been set on a 2x6 curb.


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## chandler48 (Jun 5, 2017)

I agree with Neal with the curb mount. All in all, IMO, a skylight is a hole in an otherwise non leaking roof that will have the propensity to leak eventually.


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## PatChap (Nov 17, 2012)

Deck mounts require a bit less interior finishing, as they have a finished wood interior. 
They also have more options for blinds and stuff.
Deck mounts are the higher end option, that said If your going for a basic option I would do the curb mount. 
The skylight can be replaced without touching the roof, just 8 screws hold it in.

The flashing kits are required for the 10 year no leak warranty from Velux. 
On curb mounts they are nothing special, and a little overpriced but should still be used for the warrant.
On deck mounts the flashing kits must be used sufficient flashing can't be made on a brake


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## aribert (Apr 7, 2012)

Thank you all for your responses. 

Yes, I understand that a skylight is a potential hole in the roof. In this particular house, with small windows, exterior walls that are only 7 ft and 24 inch soffits, tall shade trees and a two story house next door, having two skylights **really** brightens the interior. My workshop garage has 2 skylights and I would have more skylights in the workshop garage if I did not want to give up precious attic storage space. I like working in daylight.

PatChap: Thanks for the detailed reply. I'll have to look at how I can trim out the existing skylight openings before I decide between curb and deck mount. I sure like the serviceability/replaceability of the deck mount.


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## craig11152 (Jun 20, 2015)

We mostly ever used deck mounted but you are correct that a curb mount would be easier to replace. Of course with a curb mount you have to build the curb....not really a big deal.


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## aribert (Apr 7, 2012)

Is there any reason not to use a 2x4 curb instead of a 2x6 curb? I am thinking of the aesthetics - keeping the skylight closer to the deck.


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## Colbyt (Jan 27, 2014)

chandler48 said:


> I agree with Neal with the curb mount. All in all, IMO, a skylight is a hole in an otherwise non leaking roof that will have the propensity to leak eventually.



In most cases I would agree with Chandler but this time not so much.


We have 3 of the Velux raised deck fixed skylights that were installed in 1995 and they have never leaked not even when the outer layer of glass was broken by a golf ball. This affected 2 of them and a total of 3 times.


A new flashing kit was installed on each of them when the roof was replaced this year. We've had lots of rain this year and all still seems fine.


Our builder flatly stated that it was the only brand he would install as it was the only one he never had callbacks with.


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## roofermann (Nov 18, 2013)

Colbyt said:


> In most cases I would agree with Chandler but this time not so much.
> 
> 
> We have 3 of the Velux raised deck fixed skylights that were installed in 1995 and they have never leaked not even when the outer layer of glass was broken by a golf ball. This affected 2 of them and a total of 3 times.
> ...


I agree with your guy, the factory flashing kits are as close to idiot proof as you can get.:smile:


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## chandler48 (Jun 5, 2017)

Thanks guys, but my comment was generic. Yes, there are better and just OK sky light kits. If they are not installed properly, then that leak average goes way up.


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## aribert (Apr 7, 2012)

OK, back to my question 2x4 or 2x6 curb? I'm in moderate (not severe) snow country. I realize a higher curb moves the curb to skylight joint higher up off of the roof deck, but I like the look of a near flush mount so is a 2x4 curb too much of a risk of water intrusion between the curb and the skylight asm?


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## Colbyt (Jan 27, 2014)

Do you have 2 models to choose from? The curb is part of the skylite. 



https://www.lowes.com/pd/VELUX-Fixe...in-x-45-75-in-Actual-24-in-x-48-75-in/3280996


I am fairly sure that is the unit I have and it only projects a total 3-4" above the roof with an 11-12 pitch.


I'm sure you have a lot more snow than we do.


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## aribert (Apr 7, 2012)

Colbyt: Your link appears to be a deck mount skylight; definitely not a curb mount.


So there are 3 distinctly different skylight mounting designs: flange mount (the style that I am replacing), deck mount (where the skylight mounts directly to the roof deck, uppermost piece of the flashing kit fits under the shingles and over the upper edge of the skylight) and curb mount where the skylight mounts to a framed curb (the curb is flashed and then the skylight is screwed to the curb).

















I have bought curb mounted skylights so that if a branch drops and damages the skylight that I can unscrew the skylight and screw its replacement in place without doing any roofing. My understanding is that the flashing is sized for a 2x6 curb but can be cut down for a 2x4 curb. My preference is for a 2x4 curb to keep the skylight low to the roof - just not sure if that is a reasonable plan where there is snow/ice.


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## Nealtw (Jun 22, 2017)

We always put them on a 2x6 curb. I think that fits the roofers step flashing better.


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## Colbyt (Jan 27, 2014)

aribert said:


> Colbyt: Your link appears to be a deck mount skylight; definitely not a curb mount.
> 
> 
> So there are 3 distinctly different skylight mounting designs: flange mount (the style that I am replacing), deck mount (where the skylight mounts directly to the roof deck, uppermost piece of the flashing kit fits under the shingles and over the upper edge of the skylight) and curb mount where the skylight mounts to a framed curb (the curb is flashed and then the skylight is screwed to the curb).
> ...





*You are probably right.* The Velux site isn't real clear: https://www.veluxusa.com/products/skylights/fixed


I don't have the my actual model number. I do know the following:
it's on a northern exposure.

it projects no more than 4" above the roof
it has never leaked.
the IGU is easy to replace by removing a few screws. My local glass company made and installed the replacements



And while we don't have your winters we do get some including the 'ice storm of the century' for us back it 08 or 09. They have never leaked. There was no concealed damage to the roof deck when it was stripped in Feb of this year.



My opinion based on nothing but gut is that a 2 x 4 curb will be fine if you use their flashing kit and follow directions.


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## aribert (Apr 7, 2012)

Colbyt:

I'm hijacking my own thread but your statement is of interest. 

"...the IGU is easy to replace by removing a few screws. My local glass company made and installed the replacements...."

How did having a local glass co make a replacement glass asm price out compared to buying a new skylight?


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## Colbyt (Jan 27, 2014)

They made one trip to measure and one to install; 2 men both times because of the roof pitch. They ordered the safety glass or unit to proper size. They make IGUs so I'm not sure which they did. They sealed around the edges of the IGU before replacing the metal caps.


On a lessor pitch I might have measure and installed the IGU myself. While the bill is not itemized I imagine 2 men 2 trips was a goodly % of the total cost.



The last bill in 2012 was $254.00. Now there is no way I could be on that pitch roof to install a new skylite or even the IGU so for me it was far cheaper that having someone replace the entire lite. And I did not risk them damaging the roof or not doing it correctly.


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