Bifold Doors

[mobe]

We frequently get asked to size beams over bifold doors. What is a typical weight/m2 for these & a limiting deflection under load of door plus any live load over (eg roof over)? Thanks

 

[Chickenhawk6451]

Typically I would aim for less than Span/500 deflection or 10mm, whichever is smaller. A bit more restrictive than standard requirements because bi-folds are a bit more sensitive to deflection from what builders have been telling me.

As for a weight/m2, I'm not sure I follow. Do you mean acceptable loading on a m² basis? That will be determined by local Standards but if you get stuck i use 1kPa Dead load for floors and roofs, 0.4kPa for walls and 2.5kPa live load for flooring (3kPa on balconies and other areas). If you can get your hands on is, AS1170.0 has a great table with all these things in it, you local code might have similar in it

Cheers
Chicken

 

[jayrod12]

For those large style bifold doors I'll usually take 15 psf (0.75 kPa). And around here they typically require 1/8th inch for every 12ft of span for deflection.

 

[mobe]

Thanks for that! Great help.

 

[helfreco]

mobe, when you say 'under load of door' do you mean dead load? For large doors, a bifold should support its dead load from the floor; the track above would be responsible for stabilization and resisting lateral loads like wind.

For deflection, L/500 like Chicken suggests is a good rule of thumb. It is more stringent since you are dealing with moving parts. You can also check with the door manufacturer. They are aware the frame above deflects and have built play in their tracks for this. Very large doors (not sure how big you are getting, but like airplane hangars) can have telescoping guides to accommodate larger deflections. You can work with your door manufacturer to find out what both of your needs are. A telescoping door can accommodate several inches if need be.

 

[msquared48]

I agree with the above, but would contact the manufacturer for backup if you know who it will be.

If not, state your assumptions on the calcs/ drawings with the note to verify and contact you if different than your assumptions.

Mike McCann, PE, SE (WA)

 

[XR250]

I would def. check with the manufacturer first. I get some residential ones where they want 1/16" - totally ridiculous IMHO.

 

[Chickenhawk6451]

I would def. check with the manufacturer first. I get some residential ones where they want 1/16" - totally ridiculous IMHO.

Totally reasonable, but i'll bet that 1/16" changes real quick once the builder sees the size (and cost) of beam required to achieve it