Subfloor: Exterior or marine?

[Harriet 1400]

I've decided that I'm going to replace part of the subfloor in the back end. I believe it's 5/8", but is exterior grade okay, or should I spring for marine grade?

[boandsusan]

Exterior is fine IMO. I wouldn`t spring for the marine unless I was doing the complete floor.

[mobiltec]

Materials from the big box stores is so crappy anymore that I would go for marine if I can afford it. It depends a lot on how you protect the underside of the trailer.

[Harriet 1400]

Haha, one vote for marine and one for exterior. Mobiltec, I haven't researched the undercoat too much, yet, to be honest, but I was thinking about using something like this Herculiner:

www.amazon.com/Herculiner-HCL1B8-Brush-Bed-Liner/dp/B0002TDUW4

What would you recommend?

[vikx]

Herculiner is a mess to work with. Our Corvette had plywood walls, so I sealed the bottom with Herculiner. Still trying to get the dots of rubber of my shop floor. LOL. It's good stuff. Wear gloves.

[Harriet 1400]

I will be sure to do that, when it's time. And also hair protection. Yuck, can you imagine?

So, would exterior grade be fine with the Herculiner undercoat? Was the original subfloor made from marine plywood or exterior, I wonder?

[pathfinder3081]

I dont' know alot about "exterior grade" plywood other than the stuff I have seen at DIY stores. However, the Marine grades that I have worked with were impressive. I've seen some with almost a hard epoxy or resin embedded into one face. It's been a few years since I've seen that stuff. It had a red face and was at a Marina yard on my coast.
I used some 3/4" Baltic Birch Marine Grade Ply on my lofyte this past winter. Really nice stuff.. 4x8 @ $84.00 per sheet. You would still seal it and paint it but the glue is made to hold up if it ever becomes wet. It's dense and has zero voids.

[Harriet 1400]

Marine it is, then! We were leaning that way, anyway, but wanted some input, just in case everyone said "NO, that's overkill; no need to go to the expense!"

We'll have to make arrangements to get it out here. A 4 x 8 sheet is just too big for our vehicles.

Thanks so much for the advice.

[kto17]

Apr 30, 2013 7:22:45 GMT -5 Harriet 1400 said:

Marine it is, then! We were leaning that way, anyway, but wanted some input, just in case everyone said "NO, that's overkill; no need to go to the expense!"

We'll have to make arrangements to get it out here. A 4 x 8 sheet is just too big for our vehicles.

Thanks so much for the advice.

I don't know what area you are in, but here in the south the big box stores carry pressure treated plywood and some call it a marine grade. I would avoid the greenish pressure treated plywood. That stuff warps horribly as it dries out. I would hate to see what it would do to a camper if it wasn't secured just right.

There are lots of exposure rated plywoods now so do your research as to what you are buying. Some are only rated for 30-60 days of exposure to the elements.

[mobiltec]

Apr 30, 2013 8:55:16 GMT -5 kto17 said:

Apr 30, 2013 7:22:45 GMT -5 Harriet 1400 said:

Marine it is, then! We were leaning that way, anyway, but wanted some input, just in case everyone said "NO, that's overkill; no need to go to the expense!"

We'll have to make arrangements to get it out here. A 4 x 8 sheet is just too big for our vehicles.

Thanks so much for the advice.

I don't know what area you are in, but here in the south the big box stores carry pressure treated plywood and some call it a marine grade. I would avoid the greenish pressure treated plywood. That stuff warps horribly as it dries out. I would hate to see what it would do to a camper if it wasn't secured just right.

There are lots of exposure rated plywoods now so do your research as to what you are buying. Some are only rated for 30-60 days of exposure to the elements.

Pretty much DITTO (we need a DITTO button) on everything above. If any of you have been following my Shasta videos you know that I had to replace my floor TWICE front and rear because the expensive plywood I bought fell apart while working on the rest of the trailer. It didn't last a month before it started delaminating. Really got me POed.

[boandsusan]

Know what you mean mobile. We try to buy all our boards/lumber at our local hardware shop as its 2nd generation family owned and ran, so they are a lot more particular about the quality than the big box stores. However they only have so much room under their sheds and so once in a while if its a rush job, we do resort to a big box store instead of ordering it through our local store. I get so ticked off in the big box stores when I need something as simple as a STRAIGHT 2x4, I end up culling half a pile before I find what I want. I know they hate it when they see me coming lol.Guess tree`don`t grow as straight as they use to. If we`re replacing a small section of floor we just use treated plywood as we usually have a piece laying around. If it was a whole sheet or floor needed, I`d definately go with marine. We also slop marine topcoat (Valspar) around the outer perimiter of the floor on the top side.

[Harriet 1400]

Apr 30, 2013 9:25:12 GMT -5 mobiltec said:

... I had to replace my floor TWICE front and rear because the expensive plywood I bought fell apart while working on the rest of the trailer. It didn't last a month before it started delaminating.

Mobiltec, eeek!

KT017, we're not in the south; we're West Virginia yankees. That said, we get PLENTY of rain here, and it's very humid in the summers. I'll be sure to visit a lumberyard to get the good stuff. I'm glad you all are so generous with the advice!

[Harriet 1400]

BoandSusan, marine topcoat sounds like a good idea, too. Really, only the two back corners are bad, so not much actually needs replaced--maybe 6 or 8 inches of the very back, just to be absolutely sure we're getting to good wood. But because we're not especially experienced with travel trailer construction, we decided it would be easier to go ahead and replace the whole back sheet. That's probably overkill, but I was afraid that otherwise I wouldn't be able to center the edges on a joist.

[mobiltec]

Apr 30, 2013 10:08:56 GMT -5 boandsusan said:

Kn I get so ticked off in the big box stores when I need something as simple as a STRAIGHT 2x4, I end up culling half a pile before I find what I want. I know they hate it when they see me coming lol.Guess tree`don`t grow as straight as they use to..

Trees have never grown completely straight. It's not the tree's fault. It's because the lumber we are buying is wet. Way too green for milling and selling. They cut the tree down, mill it and ship it out before it has had a chance to dry out a little. They bundle all those 2x4s or what ever into a stack and ship and then once opened in the store and stocked on the shelves, they begin to dry out and warp. I worked for Weyerhaeuser for a while so I know how things used to be done when Quality was abound in the United States Of America. But now just about everything is done with no quality control. Profit is the bottom line.

The lumber we have been gettting for the last 10 years is SOOOO green that limbs and branches and leaves are growing inside the walls of the newer homes. I'm not kidding.

[boandsusan]

Apr 30, 2013 11:54:41 GMT -5 mobiltec said:

Apr 30, 2013 10:08:56 GMT -5 boandsusan said:

Kn I get so ticked off in the big box stores when I need something as simple as a STRAIGHT 2x4, I end up culling half a pile before I find what I want. I know they hate it when they see me coming lol.Guess tree`don`t grow as straight as they use to..

Trees have never grown completely straight. It's not the tree's fault. It's because the lumber we are buying is wet. Way too green for milling and selling. They cut the tree down, mill it and ship it out before it has had a chance to dry out a little. They bundle all those 2x4s or what ever into a stack and ship and then once opened in the store and stocked on the shelves, they begin to dry out and warp. I worked for Weyerhaeuser for a while so I know how things used to be done when Quality was abound in the United States Of America. But now just about everything is done with no quality control. Profit is the bottom line.

The lumber we have been gettting for the last 10 years is SOOOO green that limbs and branches and leaves are growing inside the walls of the newer homes. I'm not kidding.

Ditto,I was trying to be sarcastic when I refered to "straight trees" lol. As long as the big box stores continue to purchase it wet, nothing is going to change. Trees will never grow straight again lol

[kto17]

Yup. Next time your in you local big box culling thru the 2x4 look at the stamp on them and see if they are even from the USA. Before the economy took a dump I worked for a builder full time and part time at the local HD in the lumber dept. I take pride in my work and that place drove me nuts when I had to buy stuff there. They loved me when I built my 12'x25' deck. Talk about digging thru piles of lumber for a few good boards. I did at least help them clean up my mess.

I love my old house the 2x are all straight and hard as a rock. Every time I do any remodel work I reuse every bit of the old wood as possible.

Sorry, back on topic.

[boandsusan]

Apr 30, 2013 10:29:32 GMT -5 Harriet 1400 said:

BoandSusan, marine topcoat sounds like a good idea, too. Really, only the two back corners are bad, so not much actually needs replaced--maybe 6 or 8 inches of the very back, just to be absolutely sure we're getting to good wood. But because we're not especially experienced with travel trailer construction, we decided it would be easier to go ahead and replace the whole back sheet. That's probably overkill, but I was afraid that otherwise I wouldn't be able to center the edges on a joist.

.

There are lots of ways to do something and you`ll probably find a way that works best for you but this is what works for me. Drive a screw or drill a small hole where you think the rot ends. Go under the trailer and find the closest beam ahead of the screw. Now drill a few small holes up close, along the length of the beam closest to the rot. Set your saw to cut to the depth of the floor. From inside, drop a line, 3/4 inch from the drill holes. This should put you centre of your beam. Hope this helps.

Someone please jump in if they have an easier method......

[mobiltec]

Final say on straight lumber.... If God wanted houses to be straight, he would have made trees straight. The same applies to trailers.

[bigbill]

In 1980 I designed and built a predryer for Hartzel Ind. walnut saw mill prior to that they coated the end of a log with wax and let it air dry for at least a year before sending it through the mill. With the predryer that time was cut to 90 days.but the cost increased. From there I think some companies didn't wish to invest in something that takes at least a 10,000 Sq.Ft. building to house. So they started sawing green logs to cut down the cost of inventory drying and to prevent their money from being tied up so long. But it is the buying public who is at fault because we go ahead and buy it, Myself included I want something that will work as cheap as possible so like others I root through the stack to try to find usable wood.