DIY Skylight to replace roof hatch door?

[4nthony]

So I've got this old hatch in the upstairs hallway that allows access to a flat roof in a 2 story house. I don't really need roof access and having a skylight would be way more useful. We always open the hatch -- and keep it open for days, weeks at a time -- in the summer for light and ventilation. The curb of the hatch is in pretty good shape and I had this idea that I could essentially make it into a skylight by removing the hatch door and building something similar to an upside-down drawer box with an oversized acrylic bottom (top). The box would fit over the outside curb and I'd secure it from the inside, through the curb.

Modern skylights are obviously insulated, double-paned, sealed, etc. I live in Southern California where the temperature is pretty moderate all year long. If temps do drop, I could friction fit a piece of rigid insulation into the opening, but it's a 1940s era house and heat loss in this location is the least of my concerns.

Assuming I get a water tight seal between the acrylic and the frame, is there any reason this couldn't be functional for a few years until I get around to having a real skylight professionally installed?

I'm thinking something simple but with some pitch to prevent puddling:

In theory, it seems pretty straightforward and shouldn't take more than a few hours to build (I could easily knock this out before I start demolishing my countertops). What other things should I take into consideration? Condensation maybe?

Also, I'm leaning towards acrylic because:
- Easier for me to work with it than glass
- I can secure it to the frame with screws and seal the holes with silicone
- It is commonly used for sunrooms windows
- Impact and scratch resistant acrylic is available

The company that makes the hatch is still in business and they make replacement doors that have a window in them, but the window is relatively small compared to the size of the opening.

Thoughts? Humor me?  [smile]

 

[Dane]

I’ve done this.  Works fine, especially in CA.  I used polygal, which I would recommend. It has some insulating value- which you can choose by the thickness, cuts easily, and is indestructible.

 

[Bob D.]

I'm not in CA, but we have two Anderson Roof Windows in our living room so I do have experience living with them here in Southern NJ (we're at 39°N so about as far north as Sacramento).

Ours are 41x44 inches IIRC and fixed (stationary) so no venting. When we moved into the house they were plain (as in no tint) and double-insulated. And they leaked when it rained hard. I ordered new tinted glazing (but looking back should have ordered the extra dark tint) and new gaskets. They have not leaked since and that it 19 years now.

For some ideas on how they are constructed, look here:
https://aw930cdnprdcd.azureedge.net...009--400series-ventingroof-stationaryroof.pdf

The windows we have are on page 41, size RW4144S

Cons
- Greatly increases the heat load in the room on sunny days.
- VERY NOISY when it rains. You have to double the volume on the TV to have a chance of hearing it.
- All the sunlight will bleach a path across the room wherever the sun hits.
- VERY NOISY when it rains (oh, I said that already, but it's still true) :-(
- R value is much lower than insulated roof space. 2 times 41x44 inches is a lot of glass (just over 25 sf).

Pros
- You will know when it is about to rain before anyone because you'll hear the first drop to hit the window.
- They let in lots of natural light so gives the room and also the adjacent rooms a bright, cheerful feeling.
- You get a good view of the evening sky from your favorite chair.

The room has a vaulted ceiling and the light well through the space formed by the trusses between the roof and the ceiling is about 24 inches. It's trimmed out in wood stained to match the millwork in the room. But it's been bleached out severely by the Sun which it receives all the time. Plus there are some stains in the corners from when the windows leaked when we first moved in. I would like to replace it but not sure what I will find when I pull it off (is there a substrate or not, don't know) or if I should just cover it over.

Bottom line, if I was building a house I don't think I would put them in. And if I buy another house I would have to think hard about it and if I did buy that house I would remove them ASAP. Like the day after closing.

 

[Ron B]

Little tax hint for U.S. taxpayers.  If you install a skylight and it is either solar powered vented or if you put a solar power window blind in it, then you qualify for a tax credit for the  cost of installation.  The tax credit is for the total cost of installation.  The percentage has changed, I think it is 25-26% now (was 30% when I did it).  I think it is form 5695.  I admit the solar price items are expensive.  I think I paid $300 for a blind. In my case I had to install one rafter and cut another but by installing a solar powered blind I got a tax credit on the whole installation cost of the skylight. Let's say I spent $1000 installing a skylight including the skylight, flashing, drywall, lumber, roofing, etc and labor if I hired it done.  At 30% I received a tax credit of $300 which is a direct reduction in my taxes owed-i.e. this is not a reduction in taxable income but instead a reduction in actual taxes owed.  I installed myself so no write-off on labor, but basically this tax credit would pay for the blind.  It would be even more if you hired it done.  I am not a lawyer and not giving tax advice, just making you aware this is out there.

By the way, the solar powered blind is very nice.  In the summer I just lower and shut the blind by remote control to block the sun.  I like to hear the rain hit the skylight but will admit hail does make me nervous. 

 

[Peter_C]

They build fish tanks out of acrylic. *shrugs* Go for it! Acrylic glues super easy.

Cost is the bigger concern. Have you found a place to buy the plastic? Scrap recycled would be better. Weight vs thickness and rigidity. Thicker plastic can be tapped for threads. Easy enough to glue on pieces of plastic for areas requiring hardware mounting.

If it were me I would probably get rid of that whole metal contraption above the wood that creates a dark hole, and find either a commercial vented skylight solution or build one from scratch. Could even replace the metal portions with acrylic, reusing the hardware and measurements. I'd also glue a small overhang as shown in drawing, but then flush cut it, round the top edge some, and polish it. More light is always good.

 

[4nthony]

Cost is the bigger concern. Have you found a place to buy the plastic? Scrap recycled would be better. Weight vs thickness and rigidity. Thicker plastic can be tapped for threads. Easy enough to glue on pieces of plastic for areas requiring hardware mounting.

HD sells a 36 x 48 x 3/8 piece for $225. I wasn't able to find a source for the Polygal mentioned previously by [member=3078]Dane[/member] but I'll keep looking. Based on the size of the hatch opening, I would need at least a 28 x 40 piece. There are a few glass shops in the area so I'll call around and see if they have acrylic and if I can find a piece close to my needs at a reasonable price.

If it were me I would probably get rid of that whole metal contraption above the wood that creates a dark hole, and find either a commercial vented skylight solution or build one from scratch. Could even replace the metal portions with acrylic, reusing the hardware and measurements. I'd also glue a small overhang as shown in drawing, but then flush cut it, round the top edge some, and polish it. More light is always good.

The goal is to eventually remove the whole hatch and replace it with something like this Velux. We did a re-roof earlier this year before we moved in and had I been smart, I would've had the hatch removed and replaced at that time.

If I build the skylight, I'd also trim out the inside of the hatch with drywall so it looks like a typical light shaft. The hallway is narrow and in the middle of the house so unless the west facing bedroom door is open, it is somewhat dark all day. More light in the hall throughout the day would be a huge improvement.

 

[Peter_C]

How much is that Velux? Definitely something to be said for a commercially built unit. They also make the ones that are either electric, or operated by a pole so no ladder required. Don't you need a bug screen? Or to keep critters out?

This is more of a NorCal store I believe, but will give an idea on costs. They are known to be expensive. I buy direct from a plastics company, and for them that size would probably be considered an off cut, and something they would sell for cheaper as it would be just sitting on a shelf.https://www.tapplastics.com/custom-cut-to-size-plastic-sheets/clear-plastic-sheets

 

[4nthony]

How much is that Velux? Definitely something to be said for a commercially built unit. They also make the ones that are either electric, or operated by a pole so no ladder required. Don't you need a bug screen? Or to keep critters out?

HD has it listed on their site for $938, but it doesn't seem to be available for order. We didn't have too many issues with bugs over the summer when we kept the hatch open. We actually noticed more bugs downstairs coming in through open doors than we did upstairs.

This is more of a NorCal store I believe, but will give an idea on costs. They are known to be expensive. I buy direct from a plastics company, and for them that size would probably be considered an off cut, and something they would sell for cheaper as it would be just sitting on a shelf.https://www.tapplastics.com/custom-cut-to-size-plastic-sheets/clear-plastic-sheets

Sizing out a piece of cast acrylic at TAP ends up being a dollar more than the cost of the piece at HD (I don't know if HD is cast or extruded). Sizing it closer to what I actually need ends up around $165. There's probably a store down here that is similar to TAP. I'll have to look around. Thanks!

 

[Packard]

How much is that Velux? Definitely something to be said for a commercially built unit. They also make the ones that are either electric, or operated by a pole so no ladder required. Don't you need a bug screen? Or to keep critters out?

HD has it listed on their site for $938, but it doesn't seem to be available for order. We didn't have too many issues with bugs over the summer when we kept the hatch open. We actually noticed more bugs downstairs coming in through open doors than we did upstairs.

This is more of a NorCal store I believe, but will give an idea on costs. They are known to be expensive. I buy direct from a plastics company, and for them that size would probably be considered an off cut, and something they would sell for cheaper as it would be just sitting on a shelf.https://www.tapplastics.com/custom-cut-to-size-plastic-sheets/clear-plastic-sheets

Sizing out a piece of cast acrylic at TAP ends up being a dollar more than the cost of the piece at HD (I don't know if HD is cast or extruded). Sizing it closer to what I actually need ends up around $165. There's probably a store down here that is similar to TAP. I'll have to look around. Thanks!

Velux is a customer of mine.  I can vouch for the fact that they never cut corners.  They always fully engineer their systems and they insist that things are done exactly as specified. (They also pay their bills right on time.).

I would ask this question:

Is the roof hatch a code requirement?  Is ingress/egress a requirement of that code?  If so, will a skylight meet that code?

 

[Cheese]

I've installed 3 skylights in our house, 1 in my parents house and I have 3 more to install in the new garage when it's built. All are/were Velux and I can't recommend them enough. I've had no bad experiences with Velux skylights in over 30 years.
Velux really has the flashing system down, that's a huge difference between Velux & the others.

My dad didn't want to spend the extra $$ for the electric model and so it is a real PITA to open & close the skylight with a 4' long pole, although he doesn't seem to mind.
I opted for the electric models and they work really well. The 1st generation electric models were more bulky and were noisier while the 2nd generation models are A LOT quieter and have a built-in rain sensor. The actual actuation mechanism is also more robust in the 2nd generation models.

For my dad's situation, I bell-mouthed the bottom of the skylight opening so that it opened up in the room and allowed a lot more light in, other wise the light just bounces around in the light shaft, it's extra work but well worth the effort.

 

[Vtshopdog]

I've installed 7 Velux units in my house.  4 were in a new addition, (couldn't be easier) and 3 were retrofits with messy chase framing through the roof joists to attic space then 2x ceiling joists where a previous owner dropped the original 9' ceilings to 8' in our 100 year old bungalow.  Once hole is cut, getting them installed and flashed on roof deck is very straightforward, putting in the chase to your living area variable difficulty. 

Totally agree on Velux quality and ease of installation.  For all my units I purchased their flashing kits (couple hundred extra? can't remember) and paid close attention to their installation directions.

So my question for you, 4nthony is why do the project twice?  (whats the old saying "if you don't have time do it right the first time, when will you find time to do it again")  You are more than capable of building a DIY temporary unit so installing a prefabricated model should go well and save $$ in long term.  If you only want some light and the Plexi DIY unit is your end game then it makes sense, but doing that then forking over for Velux, not so sure.

 

[Holzhacker]

I'm a big skylight fan. Installed dozens over the years. Velux and Anderson along with a few off brand ones.
Not a fan of homemade skylights. Seen too many people make those and have them leak. Besides being ugly.
I don't know about your location but that ~ size skylight around here for an operable unit is +/-$1000 depending on options. That's a lot of money but its also piece of mind having a unit that isn't going to leak.
You have to go with an operable unit. Don't cheap out and get a fixed pane. Fixed pane is nothing but a heat sink into the home. I wouldn't spend the money on a motor but some do. A pole works just fine given how often you'll open or close. The factory mini blinds or shade between the glass can be nice depending on sun exposure.
Apply roofers tape to curb joints before installing the factory flashing. You might want to think about curb orientation in relation to sun exposure. The roof windows are nice for roof access but if you have kids that will be teenagers too soon I would stay way from those.

 

[Packard]

Our company only makes components for their solar tubes.  If all you want is light, this is a good option. 

Also note that a home fabricated skylight may not enhance the resale value the way a factory skylight will.

 

[Packard]

I would note that when I moved into my current home the kitchen had a recently installed non-operable skylight.  It was installed into a (probably) 25 to 35-year-old roof.  Disturbing that old of a roof was a problem.

I resolved that by adding a layer of roofing starting from just below the skylight and carrying it to the ridge with roofing about 5 feet on either side of the skylight.  That stood up until I needed a new roof (about 7-9 years later).

So, if the roof is very old, I would not disturb it.  Asphalt roofing becomes very brittle as it ages and flashing properly becomes nearly impossible.

 

[cpw]

I'm a big fan of skylights.  We have four in our house.  We never ever open them, but the extra light is great, especially in the bathrooms which otherwise would have no windows.

Just as a Chesterton's fence type check, do you have safe alternative access to the roof with a ladder?

 

[Ron B]

When I reroofed my house 4 years ago, I already had Andersen skylights.  I tried to buy new flashing for my old skylights when I found out that Andersen no longer made skylights-so no flashing available.  I had to replace with Velux.  Velux is a good product but not direct replacement size for Andersen which meant I had replace the skylights and redo the interior tunnels.  I did use curb mounted skylights which will allow me to replace a broken skylight without ripping up half the roof.  A skylight installation is not a place to cut corners.  I set the curbs on top of a silicone bead and used lag screws, and used the sticky runner membrane that comes with the Velux, being carefully with the corners.  I then put a larger layer of Grace rubber membrane (great product) over the first layer.  So the skylight was water tight even before the flashing was installed. 

My advise-don't cut corners.  If you plan to replace it later with a factory built skylight, size it so the replacement will not require much work.  Check out the Grace rubber membrane. 

 

[Packard]

Yeah.  I recall (though I cannot remember where from) this:  "Water is the enemy of a home". 

There are other enemies but water, by far, does the most damage. 

A local business owner wanted to tear down a very large house to make room for a new commercial building.  The old house was a "historic site" and he could not tear down the building.

So when it needed a new roof, he ignored that.  A few years back they condemned the building.  It is just an empty lot now, and there are so many retail and office spaces that remain un-leased that I doubt that they will build that new commercial building anytime soon.

But water did what lawyers could not:  It brought down a building.

 

[4nthony]

Wow, thanks for all the feedback. There's a lot to digest here.

I would ask this question:

Is the roof hatch a code requirement?  Is ingress/egress a requirement of that code?  If so, will a skylight meet that code?

I don't believe it is. My understanding is a former occupant was a ham radio operator and had numerous antennas on the roof. Supposedly, the hatch was installed so he could have easy access to do whatever one does with antennas on a roof. There are similar houses in the neighborhood that do not have a roof hatch. The house was built in the 40s. My guess is the hatch was installed in the 80s or 90s.

For my dad's situation, I bell-mouthed the bottom of the skylight opening so that it opened up in the room and allowed a lot more light in, other wise the light just bounces around in the light shaft, it's extra work but well worth the effort.

The opening is fairly shallow and an attic ladder was installed for access. Velux has a great page showcasing numerous light shaft ideas. If I proceed with this, I would remove the ladder, bell out (correct terminology?) the left side of this photo, and install drywall up to the rim of the hatch curb.

So my question for you, 4nthony is why do the project twice?  (whats the old saying "if you don't have time do it right the first time, when will you find time to do it again")  You are more than capable of building a DIY temporary unit so installing a prefabricated model should go well and save $$ in long term.  If you only want some light and the Plexi DIY unit is your end game then it makes sense, but doing that then forking over for Velux, not so sure.

Valid question. This old house is new to us and as we live here, we're making notes of things we want to do and things we want to undo. We're considering this house our forever home and for our family of 5, it's OK right now but as the kids age, we'll outgrow and need to expand. In one of our ideas for a future reconfiguration, the hallway with the hatch becomes a closet. If I were to take on the expense of having a Velux installed, there's a chance that it will be removed at a later date once real remodeling work begins.

Most of the projects I'm looking at for the short term are easy wins to make our current day-to-day a little nicer. The curb of the hatch is fairly robust and water-tight. Our roof is new (April 2021). Like most all of you, I like to build things. The idea of fabricating a simple lid for the hatch and illuminating a dark space is appealing, even if it is temporary (2-3 years?).

If you plan to replace it later with a factory built skylight, size it so the replacement will not require much work.

I would leave the hatch curb intact, remove the hatch lid, and fit the DIY skylight over the existing curb.

Just as a Chesterton's fence type check, do you have safe alternative access to the roof with a ladder?

Yes, there's easy ladder access if necessary.

 

[Packard]

If you know someone with a really huge pizza oven you could probably slump form this from a single piece of plastic. 

Slump forming is a glass forming technique where glass is placed over a male form and heated.  The heat allows the glass to become plastic (soft and pliable) and gravity provides the forming pressure. 

I did check online and there are videos on slump forming of acrylic.  Apparently, a heat gun is not adequate for this, though.  Hence, the "large pizza oven" (or lower temperature alternative). 

The temperature has to hover around 300 to 330 degrees F. to form.  In any event, if it were one-piece, it would eliminate any seams and the leak concerns that seams bring on.

Picture framers often have large dry mounting presses.  They heat to about 270 to 350 degrees and you can select the temperature on that.  It would be the ideal way to soften acrylic sheets.  My dry mounting press was smaller, but I believe the largest sizes are about 40" x 60". 

Here is the search I used: https://www.google.com/search?client=firefox-b-1-d&q=slump+forming+acrylic