Attic renovation: Timber dimension query

don_carlos

Howdy,
I am going to start renovating my attic into a more usable space. It currently has premade fink or W style trusses. I am going to put in knee walls on each side of the eaves and collar ties along the top. Very standard and straight forward renovation but what I would like to know is this

The house is block and the span from gable to gable end is 5.5 meters. I know it is common practice to use steel beams for the floor plate that will take the hangers for the 2x4's that will make up the floor of the attic but I would much rather use timber as I am just not familiar at all with using steel beams and will be working alone for the job. I want to know what dimension the timbers need to be that are going to span the 5.5mtr length of the attic space. Also, I am not working through a hole in the roof, I am bringing everything up through the attic hatch from inside so I am going to have to cut a scarf joint in the timbers and strap them together once they are in place. I don't know if that makes any difference with dimension. Any advice would be much appreciated, thank you.

Gumbo

Your Structural Engineer will advise on this along with all other structural alterations, fire safety provisions etc

Bonzo Delaney

don_carlos wrote: »

Howdy,
I am going to start renovating my attic into a more usable space. It currently has premade fink or W style trusses. I am going to put in knee walls on each side of the eaves and collar ties along the top. Very standard and straight forward renovation but what I would like to know is this

The house is block and the span from gable to gable end is 5.5 meters. I know it is common practice to use steel beams for the floor plate that will take the hangers for the 2x4's that will make up the floor of the attic but I would much rather use timber as I am just not familiar at all with using steel beams and will be working alone for the job. I want to know what dimension the timbers need to be that are going to span the 5.5mtr length of the attic space. Also, I am not working through a hole in the roof, I am bringing everything up through the attic hatch from inside so I am going to have to cut a scarf joint in the timbers and strap them together once they are in place. I don't know if that makes any difference with dimension. Any advice would be much appreciated, thank you.

Engage an engineer it'll be money well spent
If your not sure what your at yourself.

Calahonda52

dangerous project, not to mind the fact that without it being certified, you will have trouble selling the house.

Some food for thought here:
https://www.localarchitectsdirect.co.uk/seven-deadly-sins-trussed-rafter-construction-part-1
and
https://www.localarchitectsdirect.co.uk/seven-deadly-sins-trussed-rafter-construction-part-2

Is the house already two storey, this making it 3?

DOCARCH

Mod Note: @don_carlos

See Section 1.5 of the Forum Charter : Issues relating to the specification of structural components is prohibited. Any queries in this regard need to be dealt with by an architect/engineer privately.

As advised above, engage a structural engineer.