Hardboard for the roof

[MarksMG]

I made the mistake of using hardboard for the roof of my tear. I let it set for a month without working on it (other priorities). Well last night I went out to the garage and it appears that the liquid nail is not holding real well on it. After reading the back of the tube of adhesive it says it is not for hard board. Now my question is should I rip it off and start over or just use lots of countersunk screws to hold it down? Getting the hard board off will not be a problem but the liquid nail will be a different story. I know that I will have to grind it down. That will be some work but not real bad. I am almost sure that I will rip it off and start over but was just wanting other opinions.

[MtrngMan]

I'm no expert, but if it were I, I'd the hardboard carefully (because I would hope to re-use the hardboard). After removing the liquid nails, I'd re-install using gorilla glue, after rouging up the mating surface areas of the hard board to allow the Gorilla glue to expand into the fibers of the hardboard to get the best adhesion.

[DestinDave]

My intentions are to use a 1/8 sheet of hardboard with a 1/8 sheet of oak ply over that. I figured (without any research yet) on using PL Adhesive and staples to attach the hardboard to the spars and epoxy or contact cement to attach the oak to the hardboard. No staples or nails on the outside. Will PL work, Gorilla Glue, epoxy????? I guess roughing up the surface of the hardboard would be good no matter how I go, huh? 80-grit disc and a quick pass with a DA?

[MarksMG]

Well the hard board is now off the tear. It was not that the adhesive did not stick to the hard board but the hard board came apart. There was a thin layer stuck to the adhesive. Now it is just a matter of getting that off. Dave if I was you I wouldnt use the hard board even under the oak ply. I think that I am just going to double up luan or oak if I can get 1/8th inch oak this time.

[DestinDave]

The 1/8 inch oak is a little pricey but may be the way to go.. It's about $34 per sheet but I'm concerned about bending 1/4" around the front of The Trailer For Two and having it snap. Thanks...

[doug hodder]

Dave, here's a trick that I use on boats. I have used this only on plywood with exterior ratings, or marine grade. I don't recommend doing this on interior rated material, or any of the Home Depot birch laminated plys. (my disclaimer) I boil up about 3 gallons of water and pour it on top of the wood that has a ton of towels on it. Let it sit for a while, do it again, and it is a lot more flexible. That is what I do for compound curves on boat bows. I haven't done this on anything other than 1/4" marine grade or exterior grade ply, but it works well for me. I was able to bend 1/4" luan all the way around on my tear without using any hot water or steam. When you bend it, don't try to hold it with 1 screw with out a backer board while you get your next screw ready. It ain't gonna work. I made up a bunch of 1" boards full width of the trailer with about 6 screws pre-set. As I worked the curve down I sunk the middle screw into the spars and worked my way out to the edges. This prevents screws from tearing through the wood and evens out the material. No puckering between the screws. I agree with previous comments. Hardboard may act like a sponge, just looking for water and structurally isn't going to be as strong as a cheap ply or luan. Also check out the materials, oak, cherry, maple, birch etc... typically indicates what the top veneer is, it's still luan substrate...You're paying for the veneer, If it is going to be covered on both sides, just get the cheap luan or ply...Just my experience....Doug Hodder

[DestinDave]

Is lauan available in 1/4 marine/exterior grade and still have an "A" grade one side? I'm finishing my tear as a woodie... I guess I need to check my local hardwoods place - lots of nice dead trees there... Thanks. Dave

[doug hodder]

Dave, I've never seen luan in a marine grade, but it may exist. Typically the least expensive marine grade mohogany is Okume, there is a cheaper grade called Ocean Proof, It is made of lower quality veneers, but still look as good as Okume, (straight from the flounder bay catalog). It is lighter than honduran, or sapele, kind of pink. It does take dye well, but doesn't have the grain like a Sapele or a honduran. I used Okume on my tear, Sapele on my most recent boat. There are plenty of anilin dyes available for you to get the color you want. As a woody builder, think of the wood grain also, not just the color, you can doctor the color.....doug hodder

[ceebe]

Check aircraft spruce and specialty for ply. They have some non aircraft certified ply that iasnt 'terribly" expensive. The hoop pine 1/8 thick will bend to a 6 in radius

[OkieSailor]

It is too late to change, but what about using hard board on the interior sides and roof. I JUST finished installing it and then I found this posting.

Comments please!

I am hoping you guys with experience on this tell me I did not foul up. My daughter has an artist friend that wants to paint the interior with a mural and ceiling painting and she uses hardboard to paint on all of the time. So that is what we have installed.

I will be posting some new photos in the next few days.