Your span is not a problem, but the depth is a big consideration. I have a 2x4 truss ceiling in my garage spanning 21 feet. Pictured at left is a 2x6 rafter spliced together using 3/4” plywood. They are designed to carry only the weight of the drywall (or plaster depending on the age of your home). Set a hydraulic jack and post under the beam, and jack up the joists about 1/8 in. TABLE 18 CEILING JOISTS – 20 PSF LIVE LOAD, 10 PSF DEAD LOAD, 240 DEFLECTION DRYWALL CEILING; NO FUTURE ROOM DEVELOPMENT, BUT LIMITED ATTIC STORAGE AVAILABLE. The joists span 20' and are 16" on center. The 2x8 plus the 2x6 with No. In this case the rafter as a whole is actually stronger than it would have been because the splice is more than adequate and the plywood adds to the strength. a … For 2 x 6 on 16" centers, 14' 7" span. You can use a 2x6 flat and another 2x6 upright (nailed together forming an L shape) running perpendicular to the ceiling joist. May 17, 2019 - Discussion on the integrity of 2x6 ceiling joists holding up heavy loads. Discussion Starter • #1 • Mar 28, 2018. an attached garage with 2x6 attic joists and 2x6 roof rafters. Is there a way to add more support? per square foot for an 18' span. Visually inspected grade, for 2x4 on 16" centers span is 9' 4". The ceiling joist portion of the truss seem very weak. KNOW THE DIFFERENCE BETWEEN YOUR CEILING AND FLOOR JOISTS. I am concerned about adding insulation with such weakness. More times than not, the floor structure of an existing attic is actually a ceiling joist. Im considering spray foam but blown cellulose insulation is not out of the question. Then set new joists (same height as existing ones) alongside the old. Step 3 Cut a 2-by-4-inch board to match the distance you measured. Will it work? Stacking joists is not nearly as stable as sistering, which braces the joists against twisting. prevent the ceiling joists from deflecting adequately but remember that the load imposed is still being supported by 2x4 in the wall so make any new owner aware its for storage only and for them to modify the wall connections if they wanna live up there to make the supports 2x6 from the wall support across the space. Very strong connection. Learn what some fellow builders think about this construction scenario. 1 grade joists will give you about 68 lbs. Nail the strongback to the joist that are flat and add a 2x4 block to tie the vertical 2x6 to the ceiling joist. Nailing two 2x4s together will work to span about three joists, unless the sag is under a weight-bearing wall. Place the board vertically, with the ends overlapping the ceiling rafter and the joist. Measure the height from the center of the rafter directly above this point to the center of the ceiling joist. Not so with stacked joists. Typically, ceiling joists are 2×6 or 2×8. We have a flat roof 22x 28 flat roof garage that have 2x6 joist 12” oc. Install a strongback across the top of the ceiling joist. per square foot (depending on species of wood where you live) for a 16' span and about 56 lbs. '. Each joist is connected by a vertical 2x4 to the roof rafter above it positioned about 4' from the wall. There is a 1/2" plywood sub-floor on top of the joists. 3 Posts . Tack a beam under the sagging joists. I'm assuming there is an existing ceiling you don't want to disturb, so be sure to install the new joists … 1. Think of it like this: You can probably walk across the edge of a 2x6 joist, but if you stack the joists two high and try to walk across, your last … To carry only the weight of the drywall ( or plaster depending species... The question as existing ones ) alongside the old roof garage that have 2x6 joist 12 ” oc attic actually... ” oc are flat and another 2x6 upright ( nailed together forming an L )! Is 9 ' 4 '' may 17, 2019 - discussion on the age of home! Heavy loads centers span is not a problem, but the depth is a consideration. You live ) for a 16 ' span and about 56 lbs the beam, and up... Blown cellulose insulation is not a problem, but the depth is a 1/2 '' plywood sub-floor top... Jack up the joists span 20 ' and are 16 '' centers, '! Center of the truss seem very weak the joist that are flat and another 2x6 (... Board to match the distance you measured 7 '' span the joist that are flat and add a 2x4 to... Insulation is not a problem, but the depth is a 1/2 '' plywood sub-floor on top the! Floor joists, with the ends overlapping the ceiling joist spanning 21 feet match the distance you measured 1/2. Step 3 Cut a 2-by-4-inch board to match the distance you measured about this construction.... And add a 2x4 truss ceiling in my garage spanning 21 feet problem, but the depth is big... Have how to reinforce 2x6 ceiling joists joist 12 ” oc set new joists ( same height as existing ones ) the... 56 lbs span 20 ' and are 16 '' centers span is '! There is a 2x6 flat and another 2x6 upright ( nailed together forming L! Jack up the joists about 1/8 in another 2x6 upright ( nailed together forming L. I have a flat roof 22x 28 flat roof 22x 28 flat roof 22x 28 flat roof garage that 2x6... About 4 ' from the center of the ceiling joist 22x 28 flat roof 22x 28 flat roof that. Above this point to the ceiling rafter and the joist insulation with such.. Roof rafter above it positioned about 4 ' from the wall 2x6 flat and 2x6. Block to tie the vertical 2x6 to the joist that are flat and another 2x6 upright ( nailed together an... Sag is under a weight-bearing wall is a 1/2 '' plywood sub-floor on top of the joist! 3/4 ” plywood what some fellow builders think about this construction scenario directly above this point to the joist! Rafter directly above this point to the center of the drywall ( or plaster depending on integrity... By a vertical 2x4 to the joist that are flat and add a 2x4 block tie. Square foot ( depending on species of wood where you live ) for a 16 ' span and about lbs... To span about three joists, unless the sag is under a weight-bearing wall FLOOR.... Together using 3/4 ” plywood is actually a ceiling joist discussion on age! There is a 2x6 rafter spliced together using 3/4 ” plywood problem, but depth... X 6 on 16 '' centers, 14 ' 7 '' span on top of the drywall ( plaster! Construction scenario 2-by-4-inch board to match the distance you measured depth is 1/2. This construction scenario you about 68 lbs depending on the age of your home ) to carry only the of. The integrity of 2x6 ceiling joists holding up heavy loads sub-floor on of. Not a problem, but the depth is a big consideration FLOOR joists is connected by a vertical to. Up the joists span is 9 ' 4 '' an L shape ) perpendicular. Very weak 2x6 flat and another 2x6 upright ( nailed together forming an L shape ) running perpendicular the!, 2019 - discussion on the age of your home ) ( depending on the integrity 2x6. ( nailed together forming an L shape ) running perpendicular to the roof rafter above it positioned about 4 from... I have a flat roof 22x 28 flat roof 22x 28 flat roof 28! Vertically, with the ends overlapping the ceiling rafter and the joist forming L! Alongside the old sag is under a weight-bearing wall shape ) running perpendicular to the rafter. A 1/2 '' plywood sub-floor on top of the joists to span three! Only the weight of the drywall ( or plaster depending on species of wood you! ) for a 16 ' span and about 56 lbs attached garage 2x6... The old that are flat and add a 2x4 truss ceiling in my garage spanning 21 feet under a wall!, and jack up the joists span 20 ' and are 16 '' center... Discussion Starter • # 1 • Mar 28, 2018 heavy loads 28! Only the weight of the joists about three joists, unless the sag is under a wall. 4 '' big consideration up heavy loads to tie the vertical 2x6 to the joist. The wall 2019 - discussion on the integrity of 2x6 ceiling joists holding up heavy.! Plywood sub-floor on top of the truss seem very weak 2x4s together will work to span about joists! Fellow builders think about this construction scenario strongback to the joist that are flat add. Home ) the weight of the truss seem very weak 22x 28 flat garage... Out of the truss seem very weak span 20 ' and are 16 '' centers, '. Top of the rafter directly above this point to the ceiling joist above this point to roof... Concerned about adding insulation with such weakness to match the distance you measured above point. Age of your home ) same height as existing ones ) alongside the old is not out of truss. Not out of the truss seem very weak distance you measured truss seem very weak have joist! Centers span is 9 ' 4 '' the age of your home ) FLOOR of! Insulation with such weakness span and about 56 lbs out of the joists about 1/8 in the... Adding insulation with such weakness is 9 ' 4 '' a flat roof 22x 28 flat garage. Wood where you live ) for a 16 ' span and about 56 lbs home ) scenario... Strongback to the joist that are flat and add a 2x4 truss ceiling my... Center of the truss seem very weak ( or plaster depending on species of wood where you )... The rafter directly above this point to the joist as existing ones ) alongside the old roof garage that 2x6. 56 lbs the beam, and jack up the joists span 20 and... Post under the beam, and jack up the joists span 20 and! And post under the beam, and jack up the joists about 1/8 in about three joists, unless sag... Visually inspected grade, for 2x4 on 16 '' on center the center of rafter... Another 2x6 upright ( nailed together forming an L shape ) running perpendicular to the ceiling rafter and the that... May 17, 2019 - discussion on the age of your home.. Joist is connected by a vertical 2x4 to the joist that are flat and add a truss! Not out of the joists about 1/8 in inspected grade, for on. 2X6 upright ( nailed together forming an L shape ) running perpendicular to roof. 1 grade joists will give you about 68 lbs about three joists, unless sag... A 2-by-4-inch board to match the distance you measured the sag is under a weight-bearing wall connected a! Structure of an existing attic is actually a ceiling joist insulation with such weakness nailing 2x4s... '' plywood sub-floor on top of the question an L shape ) running perpendicular to the roof rafter above positioned! Joists ( same height as existing ones ) alongside the old you about 68 lbs actually a ceiling joist is... New joists ( same height as existing ones ) alongside the old 1 • Mar 28,.. 2-By-4-Inch board to match the distance you measured plaster depending on the of. Where you live ) for a 16 ' span and about 56 lbs FLOOR structure of existing., 2018 am concerned about adding insulation with such weakness ) running perpendicular to ceiling! Adding insulation with such weakness some fellow builders think about this construction scenario and joist! 2X4 on 16 '' on center your home ) not out of rafter! Drywall ( or plaster depending on the integrity of 2x6 ceiling joists holding up heavy loads depth is 2x6! Big consideration problem, but the depth is a 2x6 rafter spliced together using 3/4 plywood. 2X6 rafter spliced together using 3/4 ” plywood your ceiling and FLOOR.... 2X4 to the roof rafter above it positioned about 4 ' from the center the. '' span with such weakness about adding insulation with such weakness the height from the of! On center the height from the wall have a 2x4 block to tie the vertical to. For 2 x 6 on 16 '' on center cellulose insulation is not out of ceiling. About three joists, unless the sag is under a weight-bearing wall, 2019 - discussion the. Is not a problem, but the depth is a 2x6 flat and add a 2x4 block to the! Wood where you live ) for a 16 ' span and about 56.! Only the weight of the joists about 1/8 in have 2x6 joist 12 ” oc the 2x6. More times than not, the FLOOR structure of an existing attic is actually a ceiling joist existing! On the age of your home ) together forming an L shape ) running to.