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Forum topic by jinjin posted 05-07-2017 09:55 PM 632 views 0 times favorited 12 replies Add to Favorites Watch
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jinjin

13 posts in 3376 days


05-07-2017 09:55 PM

Hi

I built a deck box for our roof top deck, but after a year, the top of the deck box is a disaster. I used 1/4” plywood over 2×4 for frame. After one year of harsh sun and rain, plywood is peeling off badly. I had applied 3 coats of exterior polyurethane, but it didn’t seemed to have helped much.

What would be the most economical and maintenance free way to re-do the top side of the deck box that will last for many years against sun and moisture? I live near the beach and the box sits in the area with no cover.

Below are some thoughts I had without much research, so I don’t know how sound they are.

1. Tile—I don’t want to have to seal the grout every year…
2. Acrylic sheet—might be expensive
3. Copper sheet—might be expensive
4. Galvanized sheet metal—not sure how to deal with the sharp edges
5. Paint the plywood—not as durable…

Thank you so much!
—Jennifer


12 replies so far

View jerryminer's profile

jerryminer

812 posts in 1281 days


#1 posted 05-07-2017 11:09 PM

For a plywood cover, paint is a much better protector than a clear finish.

Galvanized SM is not a bad option—your local sheet-metal fabricator (look for HVAC contractors) can make a top with “hemmed edges”

-- Jerry, making sawdust professionally since 1976

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JBrow

1275 posts in 760 days


#2 posted 05-08-2017 02:04 AM

Jinjin,

If the only requirement is that a deck box that will last for many years against sun and moisture, a rubber or synthetic flat roof membrane applied with roofer’s contact cement to a new lid from marine grade plywood could be option 6 on your list. If the lid were modified to include some pitch (assuming no pitch now exists), water would run off after a rain and could perhaps add a little more life to the lid. But the sun will eventually take its toll.

View Carol's profile

Carol

57 posts in 353 days


#3 posted 05-08-2017 02:38 AM

how about framing a galvanized sheet with cedar, cypress or ipe? i like jerry’s idea of a rolled edge on galvanized.
imho, forget plywood. no sealant over plywood can compete with damaging uv rays and the sun’s heat.

-- Carol

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jinjin

13 posts in 3376 days


#4 posted 05-12-2017 04:54 AM

Thank you so much.
I will see if I can find galvanized steel of that size… And figure out how to “roll” the edges. Hopefully it’s pliable with regular home tools.

@JBrow
The roofing material sounds good. Maybe I can lay that on top of plywood and then add tile on top for nicer look? Even if I don’t seal the grout frequently, the roofing material should provide waterproofing, right?

Also, what do you guys think about linoleum used in flooring? It is not meant for outdoors, so I don’t know if that will melt under the Southern California sun.

Thanks again, everyone!

View Fred Hargis's profile

Fred Hargis

4766 posts in 2333 days


#5 posted 05-12-2017 11:03 AM

I think you can use plywood and have success, but you need to be choosy. One of the problems you had was using a urethane finish for outdoor, a good exterior finish will not contain that….urethanes do poorly in high UV environments. the other thing (maybe) was the 1/4” thickness of the plywood….but that’s a shot in the dark. As mentioned above, paint would be the best protection for what you have but even better may be to use MDO plywood, it’s made for outdoor signs so it does very well in the weather (I’ve not seen it in 1/4” though, it may exist but i haven’t seen ti). The second thing would be to use an appropriate out finish, that would be paint or a marine spar varnish. If you want a clear coat, you can still use paint. Just get some that isn’t tinted, the deep color base (#4 in most brands) without tint will dry clear much like an oil based varnish.

-- Our village hasn't lost it's idiot, he was elected to congress.

View ksSlim's profile

ksSlim

1263 posts in 2729 days


#6 posted 05-12-2017 11:35 AM

Marine grade ply over stringers. Marine finish, lasts 4 yrs w/ no rework.
I’ve started using SW deck finish lasts 3yrs and is half the $$.
Marine finish have UV inhibitor and are pricey.

-- Sawdust and shavings are therapeutic

View jbay's profile (online now)

jbay

1861 posts in 739 days


#7 posted 05-12-2017 01:06 PM

Plywood with,
Fiberglass cloth and resin…
It’s good enough on all the kayaks and canoes I see here!

PS: Throw a cushion on it and make it a seat.

-- If anyone would like to see my Portfolio, PM me and I would be glad to send you the link.

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JBrow

1275 posts in 760 days


#8 posted 05-12-2017 01:56 PM

jinjin

The roofing material sounds good. Maybe I can lay that on top of plywood and then add tile on top for nicer look? Even if I don’t seal the grout frequently, the roofing material should provide waterproofing, right?

If you were to lay tile on the top, using tiles with rectified edges and no grout tabs should allow the tiles to set tight against one another. This could eliminate the need for grout.

The rubber roof membrane would make the lid waterproof. However, I am not sure that attaching tile directly to the membrane would be a good idea. My first concern is ensuring the tile to roof membrane connection is secure and would last over time. Perhaps there is an adhesive that would work for bonding clay or porcelain to rubber. In another post, a LJ posted this handy link for selecting adhesives. This site may be a good place to start if you plan to go forward and stick tile to the rubber membrane.

http://www.thistothat.com/

The second issue could arise when the lid is lifted. The weight of the tile may pull on the membrane. The stress on the membrane could cause it to tear over time.

The third issue is the flex in the lid as it lifted. My understanding is that flex in the substrate can lead to tiles cracking. The substrate (plywood) would have to be beefed up quite a bit to minimize flexing when the lid is lifted. All this material; a beefed up substrate, the roof membrane, and the tile, would make the lid quite heavy and potentially difficult to lift.

Some of these problems could be solved if access to the deck box interior is through doors in the front, making the lid fixed.

Also, what do you guys think about linoleum used in flooring?

My guess is that any sheet floor good, like linoleum, would deteriorate under sunlight. But if you can find a floor material that is rated for outdoor use, it could last longer under direct sunlight and eliminate the problems associated with tiling the lid.

For what it is worth, I like jbay’s idea; waterproof the plywood lid with fiberglass and resin (or roofing material) and use a cushion to hide the ugliness.

View BurlyBob's profile

BurlyBob

5068 posts in 2105 days


#9 posted 05-12-2017 03:41 PM

I agree with Jbay. Fiberglass and resin is the way to go. You can also add colors to the resin if you wish.

View papadan's profile

papadan

3584 posts in 3208 days


#10 posted 05-12-2017 07:06 PM

Forget plywood, just use regular pine boards instead. Caulk the joints and seal with Spar varnish. This would even make it strong enough to use for a seating bench.

View jinjin's profile

jinjin

13 posts in 3376 days


#11 posted 06-23-2017 07:08 AM

Thank you everyone for your suggestion. Sorry for the late reply. I was going to fix it up and report back, but still haven’t had a chance.
I did buy roofing rubber and is currently covering the box. I will need to cut it to size and glue/nail it on and paint it. It won’t be as pretty as wood, but it will work.

Thank you so much for all your inputs!

View paratrooper34's profile

paratrooper34

915 posts in 2791 days


#12 posted 06-23-2017 01:44 PM



Plywood with,
Fiberglass cloth and resin…
It s good enough on all the kayaks and canoes I see here!

PS: Throw a cushion on it and make it a seat.

- jbay

This ^

-- Mike

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