Green Building Forum - Masonite beam construction

Masonite beam construction

dickster — Mon, 07 Jan 2008 10:36:54 +0000

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 beam construction

caliwag — Mon, 07 Jan 2008 10:44:26 +0000

Take a look at www.treehouseclapham.org.uk a house that was built using Masonite type floors and walls.
The construction was serialized in the Independent Property section and I understand there is a tie-in book, though I havn't seen it.
The Engineered beams were made by Jones of Forres (Scotland), but I bet there are many more available closer too home.

Masonite beam construction

mattstan51 — Mon, 07 Jan 2008 10:54:09 +0000

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.

Masonite beam construction

Nick Parsons — Mon, 07 Jan 2008 18:56:40 +0000

We made our own - 2 x 50 x 50, and a ply web.

Masonite beam construction

Chris Wardle — Mon, 07 Jan 2008 19:23:45 +0000

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.

Masonite beam construction

Paul in Montreal — Mon, 07 Jan 2008 19:24:33 +0000

Posted By: Nick ParsonsWe made our own - 2 x 50 x 50, and a ply web.

Hope you had a structural engineer sign-off on the design and the choice of materials. You can't just slap together some wood and ply and hope for the best - the dimensions have to be correct for the design loads together with appropriate materials. There are many grades of timber and plywood which wouldn't necessarily create a satisfactory beam.

Paul in Montreal

Masonite beam construction

chuckey — Mon, 07 Jan 2008 20:42:15 +0000

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

Masonite beam construction

Nick Parsons — Mon, 07 Jan 2008 20:49:19 +0000

Chris: Routed and glued.

Paul: No, but neither did I read the original post properly! Ours are for studding only in post and beam structure. They take no real load, but having had proprietary I-beams installed in a previous bldg I would not have deemed them as anything special.

Masonite beam construction

jamesingram — Mon, 07 Jan 2008 22:45:59 +0000

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.

Masonite beam construction

tony — Mon, 07 Jan 2008 23:04:25 +0000

Not most?? some may be.

Masonite beam construction

Paul in Montreal — Mon, 07 Jan 2008 23:11:46 +0000

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

Masonite beam construction

Nick Parsons — Tue, 08 Jan 2008 20:43:13 +0000

Accepted, Paul. I would not want to encourage anyone to incorporate a very fundamental element of a bldg which was not 100% sound. I am a great believer in spaced studs for a variety of non-load-bearing jobs, though, and these can be very basic.