vicksslc

Thanks for the insight. I'll be hiring an engineer soon to get more details to see if my project is possible. I have a huge pitched roof and the attic open space would easily be 16 x 13 leaving the existing truss sides in place, removing the middle 2x4s and converting to the pic you posted.

Just curious - to get the floor to carry living space load - how does one go about adding 2x6's or so to an existing truss system?

nealtw

The trusses probably span a great open space down stairs, Unless you can find bearing walls and or beams with bearing all the way down to the foundation, I don't think you will be able to do it with out removing and replacing trusses. thw first picture in craigs post is what your after but in hand framed roof you have to support the floor at each end plus the new pony walls to support the roof mid span. I think the 1 floor is figured at about 100 lbs per sq ft and now your adding some portion of the roof load. the engineer is the only answer like was suggested.
The hole house was engineered for trusses and would have been alot more money to build a hand framed roof.

vicksslc

I appreciate the quick response. I looked at the telebeam system http://www.telebeam.co.uk/index.php/case-study?start=6- and it looks like I need to do something similar - adding beams for the floor supported by load bearing walls below. I'll let you all know what I come up with.

nealtw

Had a look at the beam system, They don't seem to talk about rafters. the 2x4s will not be enough. When hand framing more often rafters are 2x8 or 2x10 by engineers specs. The open trusses could be installed simply by removing sheeting on one side of the house and sliding them in with a crane. I would bet it would be about half the price of beams. Look at the thickness of their roof at their skylights.

vicksslc

Good -point. Thanks for the added info.

Maybe I'll just turn it into a bit of light storage space. Doesn't seem worth the work anymore.

WoodlandConstruction

So you have an 8 pitch roof. What is the width of the structure? Im guessing 24 or 26 feet. Is there a center bearing wall? To add 2x10 joist you would need to break them on this bearing wall. Are the trusses 16 or 24" on center? The span would determine the size of the rafter needed. Installing the rafters is alot harder than you think. Trying to get them down onto the top wall plate and then to the peak is not an easy job when you have an existing roof in your way. How do you plan on nailing them to the top wall plate? You will be on your bellie in a crevice trying to nail. Not impossible but be aware it will be very uncomfortable. I may hear you swearing from hear.
It can be done, but wont be fun.

nealtw

Anyone thinking about changing trusses should read this article
Boardwalk Builders - Support for Sagging Trusses

mrdoitall

Hi

I thought I would drop a line or two because this may be your undoing
If you chose to be ill advised

You need to check a span table to determine what lumber you will need

#1 what are the existing rafters constructed of 2"x4" - 2"x6" etc.?
#2 what is the widest span?
#3 is it a hip roof or gable roof?
#4 what is the total area the roof is covering?
#5 what are you willing to spend?

I’m not going to bother with all this nonsense
Disregard the 5 questions

The critical point to if you can do it with out removing the roof or not lies at the bird’s mouth and how much top plate you have to fasten and support the new rafters
If you have the space to accommodate new truss’s from the top plate to the under side of the roof sheeting
You may need to remove the over hang portion of the roof to insert & fasten the new rafters
As well you are going to need collar-ties

I do not know what kind of roof you have or how intricate it may be
If you have hips and valleys it will be vary challenging getting the new truss’s in

dIyblognowdotcom

Yes you can cut the trusses and redesign them but only with an engineer guiding your movements. With that being said you must first see if the walls that you plan to set the floor on will carry the added weight of the floor that you plan on putting up there, remember a floor is designed to carry 30 or 35 pounds per square foot. You are asking the walls and the footer to carry a lot more weight than what they were designed to carry, be careful.