Spar on oak plywood walls?

[McBrew]

Sooooo... it's getting close to wall-making time on my first TD. I found some 1/4" oak plywood at "big orange box" and was thinking of using that for my woody-to-be. We've got plenty of boater supply stores in Annapolis... so I was thinking of using Spar on it. My questions:

1) Good idea?
2) Should I stain it first? Doesn't Spar usually have an amber tint? How noticeable is it?
3) How do I prepare the oak plywood before using Spar? Sanding? Any kind of pre-treatment necessary/recommended?

Thanks in advance!

By the way, the idea is to have 1/4" ply on the outside, framed with 1x3 (probably), insulated, and then ??? on the inside. Maybe more oak ply for an inside-woody... maybe something cheaper.

[Mary K]

Congrats on your decision to build!

I used Spar Urethane on my TD and it is working out okay. But, I do have a spot that cracked where a piece of trim meets the skin. It leaked under the skin and started to mold. I have now found out that Spar does crack where as Epoxy will give a little and stretch. I now plan to go back over all my trim edges where it touches the skin and fill with epoxy. These are potential leak points anyway and it can not hurt.

Steve Cox helped me on this issue and hopefully he will chime in and give advice.

If you want to stain, do it before the Spar. Spar does have an amber tint, but not unattractive. I prepped my wood by just sanding with 150 grit and then 220. Some just sand with 150. No pretreatment other than if you want to stain. If you do stain, practice first on some scrap. I used clean cotton rags to stain my trim.

After your first coat of stain or spar dries, you will notice the wood is rougher. This is because the grain will swell and lift when it gets wet. Make sure you sand well between the first and second coats.


Good Luck,

Mk

[Sparksalot]

I used red oak veneer plywood. So far all I've done is 3 coats of Rot Doctor CPES. It's got an amber tint as well.

[McBrew]

Thanks for the replies! Sparks, that oak looks beautiful! I have done some further reading and it looks like CPES then Spar is a good combo. I'll probably wait to find some 4x10 sheets since my TD is going to be nearly 9.5' long with the overhang.

Anybody in Maryland know where to get some nice looking plywood in larger sheets?

[GPW]

Sparks , no use just sealing the outside.... we sealed everything on ours , inside and out...less chance for Rot...

[sid]

McBrew, take a look in my album and on our website. It's birch, but I've done oak the same with marine spar varnish, and you can see how much it will change the color.

I did not use any stain. It really brings the grain out in the wood.

Mark

[McBrew]

Mark, the dragonfly looks great! By the way, what kind of molding is that between the roof and wall? That's the kind of molding I've been looking for. Is it just rubber, or is there a "backbone" to it? Does it glue on, use screws, or what? How do you like it?

[DBizer]

Mine is done with 2 coats CPES and 3 coats spar, no stain. Both the epoxy and the spar add the amber color.


David

[sid]

Mark, the dragonfly looks great! By the way, what kind of molding is that between the roof and wall? That's the kind of molding I've been looking for. Is it just rubber, or is there a "backbone" to it? Does it glue on, use screws, or what? How do you like it?

Thanks McBrew,

The molding is just a "L" shaped aluminum RV molding I bought at a local RV store. It is like what Grant carries here http://www.lilbear.teardrops.net/parts.html#molding (2nd from left).

It was white, so we scuffed it with some light sanding, primed it and painted it black. It takes the plastic insert that covers up the screws. It is very strong being that it is "L" shaped, but it's also easy to work around the curves with a rubber mallet and some patience.

Good luck on your build.

Mark

[McBrew]

David, that's a nice looking tear! That's great info about the CPES and Spar... kinda reinforces what I've been hearing.

Mark, I get it now... for some reason it looked like L-shaped rubber. My old class-C RV had that same molding around the roof with the rubber insert covering the screws. So, it's not too hard to work with? That's good to know.

[sid]

Mark, I get it now... for some reason it looked like L-shaped rubber. My old class-C RV had that same molding around the roof with the rubber insert covering the screws. So, it's not too hard to work with? That's good to know.

Believe me, it's a lot better than trying to soften aluminum from the Big Box stores!

[Steve_Cox]

Congrats on your decision to build!

I used Spar Urethane on my TD and it is working out okay. But, I do have a spot that cracked where a piece of trim meets the skin. It leaked under the skin and started to mold. I have now found out that Spar does crack where as Epoxy will give a little and stretch. I now plan to go back over all my trim edges where it touches the skin and fill with epoxy. These are potential leak points anyway and it can not hurt.

Steve Cox helped me on this issue and hopefully he will chime in and give advice.

If you want to stain, do it before the Spar. Spar does have an amber tint, but not unattractive. I prepped my wood by just sanding with 150 grit and then 220. Some just sand with 150. No pretreatment other than if you want to stain. If you do stain, practice first on some scrap. I used clean cotton rags to stain my trim.

After your first coat of stain or spar dries, you will notice the wood is rougher. This is because the grain will swell and lift when it gets wet. Make sure you sand well between the first and second coats.


Good Luck,

Mk

Chiming in..............Nothing like 8 or 10 coats of Spar Varnish.........for that deep, wet look.

[McBrew]

I asked:

Anybody in Maryland know where to get some nice looking plywood in larger sheets?

Well, I found a place near Annapolis, just a mile off my normal drive to work! The name of the place is Exotic Lumber and their website is http://www.exoticlumberinc.com/. They don't list plywood on their website, but they do stock a few different kinds of hardwood ply. I'm going up there next week to take a look. Oh, the guy I talked to said they don't keep 4x10 sheets in stock, but they should be able to get some.

[McBrew]

I went to Exotic Lumber today and took a look at what they had. Wow! They had pretty much anything I could think of, including snakewood at $300/board-foot! Anyway, they had some good looking 4mm and 6mm marine okoume ply in stock. I asked about 4x10 sheets and the owner said he could get it in 5x10 sheets -- even better!. He quoted a price of $122 per sheet, which is about what I was expecting. Unless something better falls in my lap, I'll be buying a couple of sheets of 4mm from him.

The 6mm was about $220 a sheet, so I figure I can laminate the 4mm to some crappy ply for the exterior. I dunno about the interior yet... he had some teak cabin sole that would look awesome!