Flitch beam bolt spacings

[^woody^]

Conservation?

 

[messimagician]

I believe it was designed because of accessibility and that it could be made in the loft rather than trying to get a huge UB up there. Also the hangers have something to fix to at the top of the beam rather than fixing to just the face of the timber.

Timber in a 152x89 UB would only be able to sit 125mm timber but the joists attaching to the timber in the beam are 195x45 I wouldn't have a clue if the hangers would have enough nails to support such weight

Having looked at the room myself I think a UB is possible but my friend isn't so sure

 

[jks7492]

Well first of all if the SE who designed the flitch beam hasn't specified the bolt size/spacing clearly enough for it to be built then he's not done a decent enough job...

But sounds like complete overkill to be using a flitch beam with 3 timbers and 2 steel plates for a span that size, not to mention a proper faff to install. Why not use a steel beam split into two and spliced together in the loft? Or use a timber beam with deeper timbers and lose the flitch plates? If the joists are 195mm deep then the beam can be deeper than 145mm.

I'd be going back to the SE if it was me...

 

[tony1851]

If the existing joists are 195 deep, why not build the beam out of three pieces of 47 x 195 c24 insead of using any steel?

@jks7492 - you beat me to it!

PS if it's in a loft with low eaves , you (or your SE) could argue that the floor loading will never reach 1.5kN because of low headroom

 

[messimagician]

Ah the existing joists are 70x50. The beam is supposed to be sitting above these by 20mm but he wants to keep the bedroom ceilings flush without the beam sticking down. At the same time I suppose you don't want the beam sticking out the top of the floor. It might not be possible unless he starts notching existing joists and have the beam sat in them instead but I thought the new floor needs to be independent so not to cause any cracking to ceiling. It's not possible to install two beams either so beams would be out the way in storage area, the beam is just off center of room due to how the load bearing walls run

The eave is quite narrow and won't fit the full 195mm depth of the joist but apparently that's ok

 

[tony1851]

Have you considered steel box-section as a beam? If you are supporting around 9 sq m of floor, a 100 x 100 x 10 with a 97 x 47 screwed on top should do that over 3m without excessive deflection.

 

[messimagician]

Hi Tony, would this work as an option? See attached image.

would it be correct that each beam would only take half the span load ?