Hello, start building small bungalow next year. Our architect has come up with a design with floors, walls and roof made out of masonite beams and infilled with recycled paper. All very eco and seems just what we want.

Has anybody had any experience with this type of construction, good or (more importantly) bad?

Masonite beams are fine, have seen them used several times, lots less raw material for same strength

you can by a similar beams called TJM beams.

they worked fine on the projects I've seen them on. Make sure a structural engineer calculates the sizes! :-)

Warmcell insulation is fairly standard too.

How did you attach the 50x50 to the ply web, Nick, and would a home made version get through building control? I've thought about doing this myself as I believe the Masonite beams are expensive.

Chris if you look at the treehouseclapham site, under components there is a picture of a pile of lintels. It looks as though the top and bottom of the ply is simply glued into a slot in the 50 X50s. I would like to see the BOTTOM 50 X 50 to be knot free, to maintain the strength.
If you make one, set it on two bricks, measure the gap under the centre, then sit on the centre and remeasure the gap. You now can determine the deflection. If the deflection is too small to be measured accurately, try to borrow an engineers dial indicator on a stand, you then can read the deflection directly to .001". Or even an engineers digital caliper - good for .001". Once you know this then the deflection in service is proportional to its load, under reasonable load conditions (deflection < .3% of length). Theres a lot of info here:- http://www.panelagency.com/pdf/Engineering%20ManualPAJune04.pdf
but these people use Masonite for the top and bottom webs as well.
Look out for woodworm!
Frank

Most new builds use these now and there quite common place
as mentioned above

edit ;see comment below
with regard to I beams most new (small scale)house builders I know use them for flooring joists 1st/2nd floor , and some jobbing builders use them for extensions
I was under the impression the big companies used them alot as well.

Posted By: Nick ParsonsThey take no real load, but having had proprietary I-beams installed in a previous bldg I would not have deemed them as anything special.

They may not seem special but they will have been manufactured with the appropriate grade of wood for the specified loads. In your case, there is no load so there's probably not a problem. The point I really wanted to make is that people can't just put pieces of wood together so that it looks the same as a manufactured item and have any expectation on its actual performance in a real loaded situation. This is why engineered truss companies use appropriate software to design their trusses (and manufactured I-beams) with lumber of known grade that is appropriate for the job. There are at least 6 different grades of plywood that I can think of and most of them are probably not suitable for the web in an I-beam configuration.

Paul in Montreal