replacing joists in flat garage roof

[biccus1]

Hi

I have two brick built garages next to each other with a dividing brick wall which i have removed so now one large garage.

The size of the new garage is 6m long and 5.1 m wide what i have done is to put two 50mm x 150 mm c16 joists front to back with a piece of 8mm steel flat plate bolted in the middle of the wood supported on the front pillar and supported on a pillar at the rear.

but i want to remove the front pillar to put in one large door 16ft wide !!!

i would like a roller door but do not have the head room with the centre beam there so was thinking of running new joists along side the original ones across the garage and bolting to the original joists and also joist hang the to the walls.

the original beams are 50mm x 150mm what size do you think i would need to run along side to get enough strength to hold it there are 10 original beams in the roof so must be approx 600 apart..

help please i need to do this next week as got time off work to sort it

Thanks shane

 

[noseall]

a 9" x 2" would probably be ok on span but i'm not sure about the 600mm spacing.

 

[biccus1]

what i did think about was keeping the originals there and bolt a piece of 6x2 say 1mtr long across the gap in the joists and then add say 9x2 in between these so giving me approx 16 beams over 6 mtrs some 9x2 and rest joined 6x2

What anyone think?

 

[noseall]

in addition to the joists you will also need solid bridging at 1/3rd spans, i.e two lots at 1.7m apart.

 

[biccus1]

in addition to the joists you will also need solid bridging at 1/3rd spans, i.e two lots at 1.7m apart.

Do you mean nogings or do i need to make the beams up then put them up?

what do they do?

I know the roof is not that heavy but worried about snow etc later

 

[noseall]

they are similar to noggins and are there to prevent twist and add some degree of stiffening to the roof.

each joist space will require a short piece of similar sized timber fixed their-in. two lots on spans greater than 4m. i offset or stagger them to make fixing easier.

 

[biccus1]

so over my 5.1m span i would need them at 1.7 from each end ?

in between each joist ?

also what do you think best bolt 2x9 to original 2x6 and rehang the ends or bolt 2x6 togeater with more 2x6 and fit new 2x9 on ther own?

 

[noseall]

because the existing joists are split, i.e. they are two separate lengths attempting to span one larger one, then they become a liability.

your new 9x2's will be doing all the work, making the existing largely redundant.

 

[noseall]

so over my 5.1m span i would need them at 1.7 from each end ?

yes, this will achieve 1/3rd span spacing.

 

[biccus1]

thanks for the help

Do you think the 600 spacing will be ok?

shane

 

[noseall]

thanks for the help

Do you think the 600 spacing will be ok?

shane

this i'm not sure about.

 

[biccus1]

One more thing what would be the best way to put up the joists and join them to walls as i have the flat roof on i cannot slide them in from top so can screw up one joist hanger to wall but second one will not be able to be fixed until joist is in place or would i be better with two pieces of wood bolted to the wall and sit the beams on top ?

 

[noseall]

cut slots out of the masonry and slide 'em in?

the wall plate method may be flawed because of the lack of masonry at that height. there will be little resistance to push or pull.

where's shytalkz when you need him.

 

[biccus1]

umm trouble is garages in block so would be interfering with two more garages is there no eaiser way?

shane