Alter roof truss

A

Areid

New Member
IMG_1302.jpeg IMG_1310.jpeg IMG_1310.jpeg IMG_1302.jpeg IMG_1310.jpeg Currently planning to renovate my garage and would like to create a partial attic within the roof space.
I plan to remove the 4x collar ties shown with red lines and install rafter ties all the way across which would then be used to secure floor boards to and create the attic space.
Is the above achievable/realistic or a big no go?

any advice/pointers appreciated.
 
Yes it’s certainly achievable however it’ll be as dark as hell in there. Remove one collar tie at a time, then fit the joist, remove one, fit one etc. Do not remove all the ties then fit joists as you’re tempting fate.
 
Any suggestions on the size of joists to use to span across the bottom of this roof space, to be bolted either side to the bottom of the rafters and the top collar tie removed.

Approx 5m across.

to be used for storage of a few boxes nothing unusually heavy.
 
all depends on loading but assuming weight of floor and few boxes does not exceed 50kg/m2 and joists are at 600 centres and c24 wood is used then 50 x 160 joists would be structurally ok and the deflection of 15mm would just be around the allowable limit of 14mm. Can be fine tuned with more accurate info
 
Jord86 said:
Yes it’s certainly achievable however it’ll be as dark as hell in there. Remove one collar tie at a time, then fit the joist, remove one, fit one etc. Do not remove all the ties then fit joists as you’re tempting fate.
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Or... install the joist ....then.... remove the collar !!
 
Just measuring up for the required materials. My thought was to use through bolts/large washers to secure either end of the new joists to existing rafters at each end.
Does this sound reasonable or does anyone have a better suggestion ?
 
If they’re sitting on the wall plates then nails or screws would do. Screws won’t damage the tiles of slates outside with lack of hammering.
 
Severntrent said:
all depends on loading but assuming weight of floor and few boxes does not exceed 50kg/m2 and joists are at 600 centres and c24 wood is used then 50 x 160 joists would be structurally ok and the deflection of 15mm would just be around the allowable limit of 14mm. Can be fine tuned with more accurate info
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just about to order the joists, the exact span is 4.9m plus the seating at either side (where they will be secured to the rafters with coach bolts.
I plan to use 18mm chipboard to keep the weight down, overall probably want to store around 200kg of items in the area (4.9m x 3m) will focus the boxes around the edges.
From contacting suppliers 45x145 is readily available in the length I require.

Do you think this would be suitable, from looking at joist tables this size is just slightly under.

The joist will be at 450mm centres.

I could go bigger to 170 or 190 but this becomes more awakened to install.

any advice/opinions are appreciated.
 
Areid said:
just about to order the joists, the exact span is 4.9m plus the seating at either side (where they will be secured to the rafters with coach bolts.
I plan to use 18mm chipboard to keep the weight down, overall probably want to store around 200kg of items in the area (4.9m x 3m) will focus the boxes around the edges.
From contacting suppliers 45x145 is readily available in the length I require.

Do you think this would be suitable, from looking at joist tables this size is just slightly under.

The joist will be at 450mm centres.

I could go bigger to 170 or 190 but this becomes more awakened to install.

any advice/opinions are appreciated.
Click to expand...
The actual bending moment in the joists will be less than half the allowable (even less if you are loading around the edges) and deflection about 10mm of an allowable 14mm as per building regs {in your case it doesn't really matter as long as the joist doesn't collapse) so you are OK
 
Severntrent said:
The actual bending moment in the joists will be less than half the allowable (even less if you are loading around the edges) and deflection about 10mm of an allowable 14mm as per building regs {in your case it doesn't really matter as long as the joist doesn't collapse) so you are OK
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Actually when you say around the edges do you mean at the edges of the span or along the 2 outermost 4.9m joist edges (so basically there is no load on the central section of your 3m wide storage area
 
Severntrent said:
Actually when you say around the edges do you mean at the edges of the span or along the 2 outermost 4.9m joist edges (so basically there is no load on the central section of your 3m wide storage area
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Aiming to put anything of a higher weight around the edges of joist bearing points, will fit a Ramsay ladder in the central section for easy access so the central area will be kept clear minus the weight of an aluminium Ramsay ladder.

in my opinion 45x145 should be sufficient, if there is too much movement I can always double up the joists in the future.
 
Areid said:
Aiming to put anything of a higher weight around the edges of joist bearing points, will fit a Ramsay ladder in the central section for easy access so the central area will be kept clear minus the weight of an aluminium Ramsay ladder.

in my opinion 45x145 should be sufficient, if there is too much movement I can always double up the joists in the future.
Click to expand...
Mk3 Spitfire?
 
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