Foam, 2lb or 4lb?

[Uncle Dave]

Happy Holidays all,<br /><br />Any suggestins as to which foam weight to use. Is the 2 lb too weak to provide any deck support?<br />Like under 3/8 ply?<br /><br />Thanks,

 

[Hooty]

Re: Foam, 2lb or 4lb?

Not only will the higher density foam offer more strenght, it's a lot less likely to absorb water because it has smaller, thicker-walled cells. Opened cells are what cause urethane foams to soak up water.<br /><br />c/6<br />Hooty

 

[CCrew]

Re: Foam, 2lb or 4lb?

I used 4lb, under a 3/4" deck. It's going absolutely nowhere.. solid. Under 3/8 you're going to need structural foam, as there's no way 3/8 ply will properly support weight without it. That means 4lb at a minimum. 2lb is not structural rated, is only "resistant" to water, and is basically made for filling cavities that bear no weight, and gunwale or above deck applications.. not to mention foam in place packaging. <br /><br />Were it mine, I'd use 4lb, or I'd spend the $ in ply and upgrade to 1/2" and then possibly go with the lighter foam. That would be your cheaper option I'd think. <br /><br />-Roger

 

[JasonJ]

Re: Foam, 2lb or 4lb?

I used 4 lb with 1/2 inch ply on the floor, it is solid like the rock.....