Converting an attic

nelsonjh

I have W trusses and already have a plan on how to create a room in my attic which will give me a nice sized 465sq ft bed room with a bathroom and proper reinfofrcement of the ceiling when cutting out some of the "W"s.

My question is now the "flooring" of the attic space which is 2X4, I had 2 ideas;

1. To create a new floor (joists running east to west) on top of the existing attic "floor" (joists running north south), using 2X6.

2. Reinforcing the existing 2X4 attic "floor" with 2X6's on each side of the 2X4 joists. The only problem is the joists run north to south and the house is 40 ft long (north south).

Any Idea's

Scuba_Dave

You can't cut trusses without having the load/bracing/joists etc re-engineered

nelsonjh

Thanks for your reply, it’s not that I am just cutting them out, there will be reinforcement of the "roofing" and then a carving out of some of the "W's" to create the room. I have been looking at a few jobs that have been done this way and received some explanations on how to do it, so this is not the concern.

I am trying to figure out proper reinforcement of the Attic floor, could I create a sub floor or should I reinforce the existing floor with 2X6 or maybe 2X8s?

Thanks in advance

Scuba_Dave

Again, you can't guess at this
The loads need to be engineered as does the new bracing
You can't copy what someone else did & assume everything will be OK
If the houses were exactly identical AND you were able to supply the building Inspector with the engineer approval then they would probably accept it

Have you talked to the building Dept to see what they need as far as plans?

Ron6519

I think you are oblivious to the reality of truss framing if you think you can successfully do what you've stated above.
What you are planning is at best ill advised, at worst, possibly negligent.
The fact that it's, "not the concern" shows complete ignorance of the dangers involved.
Ron

davethebuilder

Exactly Scuba Dave..

You can organise to have a structural engineer design your attic space for you, or a builder (general contractor) to build this for you?

With this in mind, trusses can be cut. BUT, the areas you are cutting out have to be supported elsewhere ie: the truss rafter is supported by the "W", which in turn is also connecting the bottom chord of the truss and which in many cases supports the ceiling below. See the cause and effect issue here?

If you cut one area such as the 'W", the rafter holding up the roof and the bottom chord holding up the ceiling no longer have any strength...

What do you do without taking the whole roof apart? If you are not a builder, then suggest you get a builder (general contractor) to do the work or a structural engineer to design your structure?

If it was my place, I would install new load bearing rafters along side the trusses in question (Large enough that they do not need support) and bolt and nail these new rafters to the existing trusses and the new rafters are fixed and seated to the top plate below.

The ceiling / new loft floor. I would install new timber floor joists (size will depend on span and load) that are separate from the existing ceiling joists (Bottom chord of the truss). I would then attach the old ceiling joists to the new floor joists for strength and connecting these with joist hangers or timber droppers nailed or screwed or similar.

Only then would i start carefully removing the truss supports.

I would then attach stud walls to the underside of the rafters and on top of the new floor which will also help brace and stiffen the whole structure.

Job done!