How would you frame / insulate these portholes.

January 15, 2014 4:58 AM

I currently live on and am restoring an old dutch barge. I started with no idea what I'm doing and am slowly working my way up to lvl 1 boat restorer. The current job is insulating. I need to cover up all bare metal with insulation (I am using expanded phenolic foam board) but I also need to make sure I have sufficient wooden framing to attach walls to (it will be tongue and groove). The problem I am currently having is to the neatest way to insulate around some portholes and also insulate and neatly frame the triangular metal ribs. I'd like to leave the nice shiny brass visible but have everything else covered up neatly.

Here are some pictures.


Uninsulated
http://imgur.com/xMsYEVo

A couple of insulated ones:
http://imgur.com/FMk2pK0
http://imgur.com/b184ogk

What are your thoughts?
Please also free to ask any questions because I expect I have explained this quite badly.

posted by Just this guy, y'know to Home & Garden (12 answers total)

Best answer: In situations like this I find it helpful to imagine or sketch the contours of the finished surfaces (in this case the paneling and visible moldings) and mentally work backwards through the process/structure necessary to install and support that imagined finished surface. Do you intend to have the paneling run up in-between the triangular gussets in every space, or will you have paneling bridge the gussets where there is no porthole and only run up in-between where there are portholes? Once you make that decision, it should be pretty straightforward to imagine where you'll need nailers to tack the paneling to. Unfortunately it looks like you've already put foam in some places where you'll need a bit of wood.

I think the bigger challenge might be finding a way to neatly finish around the portholes, covering the edges of the insulation and paneling. Custom-made round "frames" would get expensive fast, so you'll need to get creative.
posted by jon1270 at 5:32 AM on January 15, 2014 [1 favorite]

I don't have advanced technical advice to offer but I wouldn't worry about a little metal sticking out (those triangles for example). A little caulk to cover small gaps goes a long way (or the sprayfoam insulation if the gap is large) to make it look a bit more finished.

I'm sure you've already got plenty of experience managing humidity in the boat during colder temps, but asking other barge owners about moisture/breathability/vaporbarrier wouldn't hurt... I only mention it because I see that electric fitting in the photo. If moisture will be accumulating on the wall of the hull due to insulation, it could bead up and run down onto your outlet. Moisture q's may be worth thinking through.

Re: portholes, doesn't look like wood is going to be your best bet. Perhaps painting the insulation directly with something that will strengthen it/make it impervious? A friend of mine make a sink out of painting a mold with a dense, silicone paint. She found it (in France) in lots of creative colors. This is awesome, btw! Are you blogging this? Would be such fun to see more photos- Way cool.
posted by iiniisfree at 5:43 AM on January 15, 2014

Best answer: It's still not an easy job (it will require some forethought and jig building), but you can frame and extend the circular opening by laminating layers of bending plywood to the correct diameter. Bending plywood is made with the plys all oriented in one direction so you can bend it. Google "bending plywood".
posted by Benny Andajetz at 5:50 AM on January 15, 2014 [1 favorite]

Response by poster: A quick update to answer a couple of points.

As to finish, I was debating wither having the panel bridging the gussets if there is no porthole and then where there is a porthole either building some sort of arch perhaps or just boxing around the gusset. (Or a different option, but those are the ones I've so far thought of.)

The electrical socket in the picture is temporary, it will be removed and rehoused in a proper bit of trunking once the walls are insulated and trunking built.
But as to vapour, yes I've thought about it and have a bunch of vapour barrier and also aluminium vapourtape for the gaps in insulation. A very good point nonetheless.
The problem with having the metal stick out is that it becomes a colder surface for condensation to form on. That's why they need to be covered and insulated.

Oh also, I had intended to blog it, but so far it has been quite slow going and I've not taken enough pictures. I might go back and write some restrospective posts and then continue onwards. (That was I could also link back to all my ask questions since they're almost exclusively, how do I build a boat).
posted by Just this guy, y'know at 6:07 AM on January 15, 2014

If a custom built flange is too expensive, I'd probably fiberglass the cut edge and sand it smooth.
posted by Ham Snadwich at 6:56 AM on January 15, 2014

Also, any reason you didn't do spray foam instead of board? It's more expensive, but there's a couple people that make DIY kits that are reasonable.
posted by Ham Snadwich at 6:57 AM on January 15, 2014

I'd use a short piece (so 2" or so ring) of large-diameter PVC or similar pipe to "frame" the porthole (really just cover up the inside edge of the insulation).

I like the triangular ribs, personally.
posted by supercres at 8:31 AM on January 15, 2014

I'm not sure about that particular rigid insulation, but I've used spray-on expanding foam (Great Stuff in the USA is one brand) to fill gaps and joints. It's sandable and sealable and I suspect you could fill your profile and then sand and finish once it's cured.

The two things I'm wary about with using a rigid and rigidly adhered insulation are expansion rates and condensation.
posted by a halcyon day at 8:34 AM on January 15, 2014

Tiger Foam is the one I've seen most often. The big benefit in using it in a house is that it's an air and vapor barrier, and can even provide a little structural rigidity if done properly.
posted by Ham Snadwich at 11:03 AM on January 15, 2014 [1 favorite]

That foam can be shaped pretty easily with a rasp or something, can't it? Part of your solution option is to contour the back side so it is as flush as possible and then finish it with a caulk bead.

I'd also be tempted to contour the openings for the portholes to admit more light and then finish the surface with some fiberglass and resin.

Also, are you using a template or jig to cut the holes in the insulation for the portholes? They might be easier to finish tidily if they are more smooth and regular.
posted by Good Brain at 7:47 PM on January 15, 2014

Hm, a vapor barrier will be important.

If the insulation has gaps, especially at the top and bottom of any rigid foam insulation, you're going to make a dehumidifier out of your wall.

Your portholes will also condense humidity, which will trickle down onto whatever is below them. Not sure hot to fix that.

For insulating the ribs, what if you used a mineral wool blanket? Flexible, can be wrapped fairly tight... not sure how it would play with the solid wood, though.
posted by anthill at 2:20 PM on January 16, 2014

Response by poster: Further updates to belatedly answer raised questions:

I'm using the board insulation over sprayfoam for two reasons.
1: To do sprayfoam I'd pretty much have to know what I wanted to do and plan it all out before doing anything (which is a good idea usually, but I'm learnign as I go, the board insulation is more forgiviing)

2: It is an old old boat (over 100 years old). If it were brand new I would have no hesitation in sprayfoaming, but because it is old I want to be able to get to the hull if need be. It's also not a nice simple new hull there are bits added and removed over time, makes it fiddlier.

It's not rigidly adhered, it is adhered with Marine Flex. Also the board itself has some flex to it.
Expansion isn't a problem.
Condensation though, that is. The gaps in the insulation are all filled with a high quality expanding foam spray rated for thermal and vapour insulation. All joints are then sealed with aluminium tape (The insulation itself is a vapour barrier). I'm also planning a vapour barrier on the warm side once insulated. That's why those metal fins need to be covered up.
I am a little paranoid about condensation. Steel boats rust from the inside out.

Thanks for all the answers so far, they've all really helped me think about the project.
I think the laminated ply rings for the portholes are probably going to be at least part of the solution. Not quite 100% on the rest of the wall though.
posted by Just this guy, y'know at 2:31 AM on January 20, 2014