Thursday, July 28, 2016

Paradise ponders...

Paradise ponders...  There's some progress on our construction to report.  The excavated soil has been removed from around our new foundations, and some good topsoil has been brought in to fill in some low spots.  This morning, a truck drove in and dropped off the lumber for the sub-floors, I think enough for both the sun room and the mud room.  Some photos below.

The joists are interesting for how they're made (see ends in the first photo below).  In the bad old days, we'd have used solid fir 2x10s or maybe 2x12s (for a long enough span).  Not any more.  The joist of choice these days is 100% engineered wood.  The web (the long vertically-oriented bit of each joist in the first photo) is OSB (Oriented Strand Board) with the chips deliberately randomly oriented.  This provides a nearly ideal web, with equal strength in either tension or compression in all directions.  A solid board, with its grain oriented along the length of the board, must be thicker to achieve the same strength.  The flanges are made of 10-ply plywood, roughly an inch and a quarter thick.  These plies are all oriented linearly, and they are all clear (free of knots).  Taken together, they have the strength of a piece of perfectly clear solid wood, even though they're much longer than one would normally be able to buy clear wood.  They're perfectly straight, and not prone to warping.  They're also much cheaper than clear wood, as they can be made from short sections butt-jointed together (with only one layer jointed at any particular location).  It's really quite ingenious how these engineered wood joists simultaneously improve quality and strength while lowering cost.

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