Convert permanently fixed skylight into removeable one as a roof access hatch?

[Bob Blarney]

Hello,

I've removed the 18" x 26" bathroom skylight from my '94 28' Excella Classic for refurbishment/recaulking/ resealing, and I think I would like to convert it to a hinged skylight that can be removed. Aside from ventilation, I could use it as an access hatch to the roof for inspection of the other roof penetration fittings. Has anybody done this already?

[james.mileur]

Originally Posted by Bob Blarney

Hello,

I've removed the 18" x 26" bathroom skylight from my '94 28' Excella Classic for refurbishment/recaulking/ resealing, and I think I would like to convert it to a hinged skylight that can be removed. Aside from ventilation, I could use it as an access hatch to the roof for inspection of the other roof penetration fittings. Has anybody done this already?

Hi Bob,
are you thinking about a bunkbed style ladder? I'm not sure if they sell step stools/ladders narrow enough for the hallway and tall enough to get you up enough for topside inspection. Guess you could make your own and stow?

James

[HiJoeSilver]

I like the idea. It'll just take some engineering and fab work to make it happen.

[dznf0g]

There was a member who installed a boat hatch for just your reason several yeares ago. I do not remember who it was, but search on skylights or maxim threads. Maybe you'll hit it.

[Bob Blarney]

Originally Posted by james.mileur

Hi Bob,
are you thinking about a bunkbed style ladder? I'm not sure if they sell step stools/ladders narrow enough for the hallway and tall enough to get you up enough for topside inspection. Guess you could make your own and stow?

James

At the moment I'm able to use a stepladder so that my waist is just below the opening and I'm able to reach both the bath vent and stack vent that I'm replacing, as well as clean up and tape the skylight flange. I haven't figured out about how I would refurbish the A/C seal/caulking

An 8-10ft telescoping ladder would probably be excellent. But for now I have an extension ladder that could be separated and I think it's narrow enough to fit the opening.

[mschneid]

If you were using a high quality skylight like the Maxim (aluminum frame) you should be able to make it work.

[dower.bill]

Well, now.

This kind of idea is why I keep checking this site. Thanks for this, I am not ready to start any action in this direction at this point, but I do love the thought. And I appreciate the input from those with more experience, to help clarify which clever ideas are maybe a bit beyond the edge, which could be done if certain issues are taken into account, and which are straightforward, based on the accumulated knowledge.

Thanks everyone.

[Bob Blarney]

After giving this some more thought, I have developed some ideas.

There is a white PVC trim board made for exterior house trim, and it may be suitable for the rectangular frame. The frame will fit over the existing roof flange, and have an EDPM weather seal on the bottom edge where it rests on the roof.
The corners could be solvent welded with plumbers' cement. A question will be the amount of expansion and contraction of the PVC material with temperature changes, so that the glazing does not pop off or crack due to mechanical stress.

The glazing will be a plastic, either acrylic or polycarbonate. I believe that it's thin enough to form an arch that sheds water, so then the next question is how to fasten it to the frame. There are double-sided tapes with very high bonding characteristics such as the 3M VHB series, but I'll need to consider whether a tape seal could hold things together under all conditions. I suppose that for added insurance, I could drill a few oversized holes for screws, and use stainless steel screws with neoprene sealing washers underneath.

[DavidsonOverlander]

I would be looking at building with aluminum rather than PVC. It will be longer lasting and will hold fasteners better. There is a wide range of extruded aluminum available to work with, and you might even get by with easy-to-find aluminum angle. It might involve welding at the corners, but if you have everything ready to go the cost to do that should be minimal. I would also sandwich the polycarbonate between layers of aluminum with a good sealant rather than relying on the sealant (or sealant and screws) alone.

[Bob Blarney]

I think aluminum presents its own set of issues with fabrication. The range of commonly available sizes of material is small, and there is still the problem of expansion and contraction. So far as holding fasteners goes, I'm not convinced that that is an important issue for this purpose.

The PVC material for house trim is engineered to perform and hold fasteners (e.g. pocket screws) like wooden trim for many years, and solvent-welding PVC is easily achieved in home shops. Moreover, it is easy to cut and finish to a desired shape with common woodworking power and hand tools.

[65CV]

For a couple of ideas from the boating world, search westmarine.com for Lewmar Hatch and Nicro Solar Vent.

I have an older trailer with a removable Astradome. I'm making a "storage cover" that will have the Nigro Vent installed -- storing the trailer for a couple months in Arizona this year and want to get some heat out! Also good for removing moisture.

[Bob Blarney]

Yea, measure not once, nor twice, but thrice...

I'd made some initial notes as I was working on the roof, and then I made some 'careful' measurements with a tape measure. Well, when it came down to cutting the material today, I thought it might be a good idea to check again.

I used two carpenter squares to bracket the existing flange, and then discovered that the flange had been racked into a rhomboid parallelogram when it was installed. it's about a 2 degree out of square on the corners. If I had made the hatch to my original measurements, it certainly would not have fit. It's no wonder that the original cover and interior garnish/trim are so oversized! They compensate for the poor workmanship.

[Bob Blarney]

Made from 3.5" x 96" PVC fascia trim board, acrylic sheet, 3M Outdoor Permanent Mounting Tape, stainless steel screws with neoprene sealing washers for insurance. It still needs weatherstrippong on the bottom and latches to hold it down tight, and also neat finish work of the interior frame, but it's watertight for sure. The frame was glued and pocket-screwed, and the holes in the acrylic were drilled oversize with a pointy 1/4" ceramic tile bit since a bit for plastic wasn't available.

[Bob Blarney]

The skylight hatch has proven to be weatherproof through some heavy wind & rain without being dogged down tight while the AS is parked. It's very nice to look up and see the clouds go by. As soon I'm done getting some other things done in prep for the Fall and Winter, I'll work out the details on the latches and then trim out the inside for beauty.

[james.mileur]

Looks great.