Can I add a loft to this truss?

[woodlandfarms]

I have this carport. Looks like the trusses are 2X4. I want to put up some sheets of plywood to create a storage area, but it is right where the 2X4s seem together. Before I collapse this on my tractor, does anyone have any thoughts?

Here are some pix.

 

[George2615]

For a general storage area above those rafters I'd get some additional 2x4's to put over the joint from the other side and drill some 1/2" holes thru both pieces and bolt the new 2x4 to the old one with 1/2" bolts, nuts and large flat washers on each side. Then lay your plywood.

 

[Sackett2]

without modifications I say no. those patches are not providing downward support from what I can see.
Other peoples votes?

 

[czechsonofagun]

I would not do that. The bottom 2x4 main purpose is to keep the pitch of the roof, without this tie the roof could go flat

I would reinforce it or/and support it in the middle before using the space above it. The question also is if the walls of the garaqe are built to hold more than the roof. I quess it all depends what you want to store there - bails of fiberglass insulation it would hold now; few cubic yards of lumber for drying - you can not reinforce it enough.

 

[Farmerford]

If those trusses were built by a truss manufacturer, so that the metal tie plates at the center of the lower chords are well pressed into the wood, I think you can put a moderate load on the bottom chord if you install a king post on each truss (verticle 2x4 from the center of the bottom chord to the peak). The trusses appear to span about 20' and to be less than 2' on center. If you don't have snow, and the roof is not very heavy, I would guess you can safely put 5#/sf more load if you distribute it fairly evenly over the lower chords. The local design standards here in south Georgia call for (I think 1' of snow) and ceiling weight of 10#/sf, which allows for ceiling tiles, light fixtures, etc.

If it were me I would add a king post to a couple of adjacent trusses, put a 1/4" plywood or 1/2" particle board floor across them around the center, and store about 100# on it and measure the sag of the center of the lower chord. I bet it doesn't drop 1/4".

Course, I won't be standing under it when you try.

 

[EddieWalker]

No.

The bottom chords are to pull the walls together so that the angle of the top chords do not push them out. This creates a triangle that will not go anywhere. The bottom chords are ony designed for that force, holding the walls straight up and down. The plates that hold the chords together are not rated for a load, just the pull of the lumber in an outward direction.

If you feel it is something that you really want to do and create a storage area in that attic space, then you will need to create an platform independent of the roof truss. You can add to the truss by sistering lumber to the sides of what is in place. The size of the lumber needs to be determined by the length of the span. Then you will need to have it supported properly. In this case, with proper bracing and support, multiple kind studs that tie into the wall at multiple poinds should be sufficient. I'd want those kind studs to be attached to a wall stud at the very minimum.

It would probably be cheaper and easier to extend the length of the roof for more storage without worrying about damaging the integrity of your building. Lay some brick or block, pour some concrete of whatever for a floor and you have an inexpensive storage area.

Good Luck,
Eddie

 

[radioman]

No way ! you really need to sister in new supports for each one of those bottom trusses. If i was on a low budget, and cant afford anything, at the very minimum - i would nail in 2X6's that is long enough to reach each end of posts and then throw on some plywood on top and store only light things.

 

[schmism]

Oh this one i can answer as a former truss engineer.

do you have the truss drawings for those trusses?

how old are the trusses? What building code was used?

If it was fairly recent then they may have been built with a non-concurrent bottom chord live load of 10psf. That would only get you storage of a few xmas decorations.

the key on truss design is total load. If they were designed for 20psf TCLL and you only have 15 you can sometimes take that extra 5 and put it on the bottom. Not always, depends on lumber grades and webbing design.

if you knew who built them, your best source is to go back and ask them what you could put up there. OFten times you can get a sealed engineering repair to add additional storage load to trusses if you go back to the original supplier.

 

[schmism]

The plates that hold the chords together are not rated for a load, just the pull of the lumber in an outward direction.

a bottom chord splice plate will always be sized for tension force first. the tension force in a bottom chord is orders of magnitude larger than moment forces due to bottom chord live loads. as such any BC splice plate will likely pass the moment check even for basic storage loads.

Many times you see repairs to BC splice plates in the form of scabs applied to both faces of the truss. The 9 times out of 10 those scabs are required not for a moment failure of the plate, but that the increased load on the truss has increased the tension force in the bottom chord and thats what the repair is ment to cover.

 

[woodlandfarms]

Well, darnit. I guess I am going to have to build a whole new shop. You guys... all you do is cost me money ;-)

Thanks for stopping me before I brought the carport down...