water proofing your wood

[eaglesdare]

i laugh everytime i read the title of this thread (i do have a dark side to me )

[bonnie]

Snort, Snigger,

[PcHistorian]

waterproof my shingles... hmmm.... well I figured doing the wood, layer of spray-tar undercoating, layer of tar paper, then shingles.
What about the underneath wood? I've been thinking of undercoating with spray tar undercoating since I can't account for any previous stuff and it's an hellish nightmare to paint "UP" with anything so viscous as a stain. (spraying will change the color but soak in?!? maybe a power roller! (I sort of got the under side of the roof/ceiling done. I'm talking now about the bottom / ground side of the trailer. I tried to do "thompson's water seal with a paint brush" and got about half way. I THINK I got more on the wood than my hands...

[working on it]

I just finished sanding away the uneven cut marks on my door edges (roto-zip thru 2 thicknesses of 3/4" plywood = wavy lines, don't try this at home!), and fine-sanded the surfaces with 120 grit to remove footprints and dings acquired in being underfoot for 3.5 months. Then I used 50/50 mix to seal. One coat. I will do another tomorrow, since I ran out of poly. I previously tested the 50/50 mix on one side of my galley shelf to-be, and liked the way the 2 coats penetrated thru the edges and showed wicking to about 4 inches up/around on the other surface. Just a test piece, to be used inside and covered with tile or formica when used, but it proved the mix works. Though I did the test piece a month ago, and tested it with water, no delamination began. Besides, the main waterproofing will be the enamel finish, and rubber flashing tape over vertically oriented plywood edges. The reason that I used it 50/50 was to see if I could skip the 75/25 > 50/50 > 25/75 > 0/100% mineral spirits (thinner)/polyurethane progression. After a second coat of 50/50 mix, I'll go to 100% and then see what I've got. I liked the way the grain shows, and probably will leave the interior just that way. But I want an enameled glossy look outside, and heat-reflectve paint topside.

[PcHistorian]

well, now that the snow has melted I took a really god look at my shingles and I may need to repair them soon. the good thing is I now date the trailer to the mid to late 1980's, due to shingle deterioration.
does vinyl siding have a date of manufacture stamped into it?

[GPW]

Quote: " The reason that I used it 50/50 was to see if I could skip the 75/25 > 50/50 > 25/75 > 0/100% mineral spirits (thinner)/polyurethane progression” ... Wonder where this came from ???

[working on it]

Quote: " The reason that I used it 50/50 was to see if I could skip the 75/25 > 50/50 > 25/75 > 0/100% mineral spirits (thinner)/polyurethane progression” ... Wonder where this came from ???

Maybe I've misread the formula, or I just assumed that a thinner initial application was needed for total penetration of the thicker plywood I'm using. The test of 50/50 showed good enough saturation that I was encouraged to run with it. Remember, I have no experience with waterproofing wood, and don't know how to judge the end results. And, some other material I've read elsewhere had led me to believe that more solvent would drive the existing moisture from the wood, to be replaced with poly.

[PcHistorian]

ok, so this stuff keeps moisture from dissolving the glue, what about ice getting in the edge and expanding, and tearing it apart that way? caulk? heavy paint? bondo? how do I seal the edge of plywood (I am going to be getting some to build my wheel wells with I guess. Either that or I have to paint to fiberglass reinforced panels.

[GPW]

Wood , even plywood , is basically composed of many little tubes , That’s how wood grows .. and they are subject to capillary action , which means it wants to suck up water naturally ... Saturating the wood with the mix means the poly soaks into the tubes , making them “plastic coated” and resistant to Rot. (bacteria) End grain exposes the tube openings , so must be extra sealed ... ( several extra coats on the exposed edges.)
On plywood all these “sheets of tubes" are glued together with another glue ... Which , depending on the glue , means you have to either protect that too , or if the correct glue is used , just protect the wood itself ...
With the revelation of different glues being used now , the mixture may have to be adapted to the type of glue used to fabricate the ply . Some being water resistant , some solvent resistant ... which is not immediately apparent at the time of purchase... Which complicates the waterproofing selection... so basically , if the ply is made with water resistant only glue , the solvent may weaken the bond ... With a solvent resistant glue (which used to be the norm) , the Min/poly mix works fine ... just as it would work fine on plain (non ply ) wood ...
On the new ply a mix of T3 and water may (or may not) be a better choice .... in either case the ends , and end grains MUST be protected ... so extra applications are prudent ... Once any wood is properly sealed , water can’t get in , rot can’t happen , and ply can’t de-laminate ... Hopefully ....
I did see the new ply with the “sawdust" core ... That can’t be good ... but it still can be protected...


Ps. on my little Foamie’s ply floor , I used plastic wood filler on all the edges too as extra insurance ,that and the ply had Voids which were like rivers in wood .. Seems the box stores no longer handle GOOD plywood ... so it may require a search to find a quality product .... and it will be Pricy ... But if that’s what it takes , remember about what Mike says about using quality materials ...

[bonnie]

just to clarify something -- would I use the mix on all exposed wood surfaces, even if I planned on covering the shelves with formica?

[PcHistorian]

@bonnie, ply-wood I would. (pun intended) Is there ever going to be a spill on it? Water seepage at the edges...(joints of the surface?) Is storage upside down going to be possible?

I'm amazed that the bottom of my trailer is not covered and particle board. I'm going to be putting insulation under there, besides the water tanks, and sheath storage for awning, table, possible solar stuff. But still... Your formula, maybe spray tar auto undercoating. Then the insulation, etc...

[atahoekid]

Hey GPW, 3 questions about the magic elixir as I'm working on the Road Foamie this week

1) I've coated one area with the mix just for waterproofing. If I hadn't waterproofed it, I would have left it bare wood. Does this absolutely need painting over or can I leave it as is?

2) I inadvertently coated an area (4 coats) that will need glue later. I think if I rough sand well, I can get enough tooth for bonding. Your thoughts???

3) Do water based paints work well over the mix? With all that thinner, I fear that water based paints might not work well... What's your experience been?

Thanks for your expertise....

[GPW]

1. It doesn’t really NEED paint , but if you leave it bare it would look nice with some full strength poly as a “finish” ...
2. Probably ... depends on the glue ... GG would stick ... T2 , I don’t really know ... Time for a test sample ...
3. You let the thinner DRY thoroughly , it evaporates ( couple days ) ... I painted Latex ext. house paint on my Big TD after the mix ... no problems .... stuck just fine ...

When ever in doubt ... test first ...

[atahoekid]

You're right about testing, but I knew you probably had the answers Oh, Wise One. thanks

[GPW]

Sorry to disappoint ... not really wise , just experienced using this stuff ... Just a Builder !!