I want to glue some PT boards together to make a deck for a swim platform and have them very waterproof. Will biscuits swell properly with urethane glue? I have a large bottle of TitebondII, but don't think it is sufficiently waterproof for this application.
(If not, maybe I will try that glue-joint router bit I have never used...)
Try titebond III - it's new, better than urethane and waterproof. it's the green label bottle.
I constructed a deck storage box (24 x 48) about 4 years ago and used poly glue for the M/T lid and for the butt joints on the box. I stained it with semi-transparent (Behr) stain.
No problems so far - joints still tight (allowing for the P/T wood shrinkage factor).
It is not adjacent to the pool, so not soaked daily. I cover it woth a tarp during the snowy months, but not during the rainy spring/ summer/fall.
Lou
No, they don't swell at all -- but they don't really need to, either. The urethane glue forms a pretty strong bond. In any event, the principal benefit of biscuits is to aid in alignment of the joint, and not to add strength: the strength comes from the glue bond between the edges of the boards.
You're better off with a box of 16d galvanized spiral deck nails.
I have my doubts that *any* glue is going to work for long in this application. No finish short of total encasement in Lucite is going to make your platform waterproof. After a few years/months/weeks/days (depending on where you live), the UV in sunlight will have degraded any finish you put on. The platform will be exposed to repeated soaking and drying cycles, hence repeated swelling and shrinking cycles, and the glue joints will eventually break. Further, the PT lumber is going to twist and warp as it dries, too. IMO you can count yourself lucky if any glue survives two years in this use.
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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it isn't REALLY "waterproof". it's water resistant. You gotta read the fine print.
David
snipped-for-privacy@earthl> Try titebond III - it's new, better than urethane and waterproof. it's the
on second thought, i think i would consider using cedar and shiplap the joints. if you prefinished the boards, you could add a bead of clear caulk in the shiplap during assembly. I'm uncertain as to why you need a watertight deck, but water has to go somewhere. You may be able to cut a channel in the deck or slope it in the direction you want the water to go. In any case, keep in mind that galvanized fasteners will stain cedar (and redwood for that matter) so another metal fastener, such as stainless steel , would make a better choice. I built many decks and have not yet been challenged with making one watertight, but i do know the characteristics of PT. I can say for sure it has a tremendous shrinkage rate, and easily checks, making way for splinters in your feet. I've used 2x6 tongue and groove and some of the boards shunk so much the tongue and groove were barely touching each other after time even with 3 16d twistie nails per row! You could leave the boards out in the sun for some time until they dry out for use, but they have a tendency to twist and bow as they dry (about 1/3 of them would be useless and have to be returned for straight ones) I personally don't recommend PT to finish a deck for these reasons. PT is fine for the framing though. If cost is not a problem, you also may want to consider vinyl (hate so suggest this on a WW forum, but vinyl can be far superior to wood in some cases) please keep us informed as to your choice and how it turns out. -dave
"toller" wrote in message news:LcOVc.1788$ snipped-for-privacy@news01.roc.ny...
I've used the PU glue with biscuits for some gates and arbors a few years ago and they have held up fine. Don't know if it is really necessary, but I dunked the biscuits in water before inserting in the slots.
I've had similar success with Gorilla glue.
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