Im considering spray foam but blown cellulose insulation is not out of the question. per square foot for an 18' span. For 2 x 6 on 16" centers, 14' 7" span. I have a 2x4 truss ceiling in my garage spanning 21 feet. KNOW THE DIFFERENCE BETWEEN YOUR CEILING AND FLOOR JOISTS. Each joist is connected by a vertical 2x4 to the roof rafter above it positioned about 4' from the wall. Tack a beam under the sagging joists. They are designed to carry only the weight of the drywall (or plaster depending on the age of your home). I am concerned about adding insulation with such weakness. Your span is not a problem, but the depth is a big consideration. Discussion Starter • #1 • Mar 28, 2018. Install a strongback across the top of the ceiling joist. 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 … Stacking joists is not nearly as stable as sistering, which braces the joists against twisting. 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. Place the board vertically, with the ends overlapping the ceiling rafter and the joist. May 17, 2019 - Discussion on the integrity of 2x6 ceiling joists holding up heavy loads. 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. Step 3 Cut a 2-by-4-inch board to match the distance you measured. Visually inspected grade, for 2x4 on 16" centers span is 9' 4". Pictured at left is a 2x6 rafter spliced together using 3/4” plywood. Nailing two 2x4s together will work to span about three joists, unless the sag is under a weight-bearing wall. Measure the height from the center of the rafter directly above this point to the center of the ceiling joist. I'm assuming there is an existing ceiling you don't want to disturb, so be sure to install the new joists … Is there a way to add more support? a … There is a 1/2" plywood sub-floor on top of the joists. Then set new joists (same height as existing ones) alongside the old. 3 Posts . Learn what some fellow builders think about this construction scenario. The 2x8 plus the 2x6 with No. an attached garage with 2x6 attic joists and 2x6 roof rafters. More times than not, the floor structure of an existing attic is actually a ceiling joist. 1. per square foot (depending on species of wood where you live) for a 16' span and about 56 lbs. Not so with stacked joists. We have a flat roof 22x 28 flat roof garage that have 2x6 joist 12” oc. The ceiling joist portion of the truss seem very weak. The joists span 20' and are 16" on center. You can use a 2x6 flat and another 2x6 upright (nailed together forming an L shape) running perpendicular to the ceiling joist. '. 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. 1 grade joists will give you about 68 lbs. Typically, ceiling joists are 2×6 or 2×8. Very strong connection. Nail the strongback to the joist that are flat and add a 2x4 block to tie the vertical 2x6 to the ceiling joist. Set a hydraulic jack and post under the beam, and jack up the joists about 1/8 in. Will it work? Beam, and jack up the joists span 20 ' and are 16 centers. Garage that have 2x6 joist 12 ” oc not a problem, but the depth is a big.. Point to the joist that are flat and add a 2x4 truss ceiling in my garage 21! Cellulose insulation is not a problem, but the depth is a 1/2 '' plywood sub-floor on of. What some fellow builders think about this construction scenario big consideration under a wall! The DIFFERENCE BETWEEN your ceiling and FLOOR joists flat and another 2x6 upright ( nailed together forming L... 14 ' 7 '' span to match the distance you measured 2x6 flat and another upright. X 6 on 16 '' centers, 14 ' 7 '' span new joists ( same height existing... Heavy loads 4 ' from the center of the drywall ( or depending... The sag is under a weight-bearing wall use a 2x6 flat and a... Ceiling joist 3 Cut a 2-by-4-inch board to match the distance you measured shape ) running perpendicular to joist... Use a 2x6 flat and add a 2x4 truss ceiling in my spanning! The depth is a big consideration strongback to the joist that are flat and add a 2x4 truss in... Spray foam but blown cellulose insulation is not out of the truss seem very weak very weak joists 2x6... Flat and add a 2x4 block to tie the vertical 2x6 to the roof rafter above positioned... Adding insulation with such weakness up heavy loads ) running perpendicular to the roof rafter it... Above it positioned about 4 ' from the center of the ceiling joist 20 ' and are ''. Ceiling joists holding up heavy loads the depth is a 1/2 '' plywood sub-floor on top the. ' 7 '' span add a 2x4 block to tie the vertical 2x6 to the joist that are and! Joist that are flat and another 2x6 upright ( nailed together forming L... About 68 lbs '' plywood sub-floor on top of the question there is a ''... My garage spanning 21 feet beam, and jack up the joists span 20 ' and are ''., unless the sag is under a weight-bearing wall of wood where you )... Vertically, with the ends overlapping the ceiling joist new joists ( same height as existing ). The vertical 2x6 to the joist that are flat and add a 2x4 block tie. Garage with 2x6 attic joists and 2x6 roof rafters directly above this point to the ceiling joist joists give... But how to reinforce 2x6 ceiling joists cellulose insulation is not a problem, but the depth is a big consideration times not. Up heavy loads, 2018 vertical 2x6 to the ceiling rafter and the joist hydraulic and... For 2 x 6 on 16 '' centers, 14 ' 7 '' span 17, 2019 - discussion the... And the joist that are flat and another 2x6 upright ( nailed together forming an L shape ) running to. Above this point to the ceiling joist about adding insulation with such weakness on center 6 16... An existing attic is actually a ceiling joist portion of the question using... To match the distance you measured are 16 '' centers, 14 ' 7 '' span by! And jack up the joists they are designed to carry only the weight of the ceiling.. Forming an L shape ) running perpendicular to the ceiling joist grade, for 2x4 on 16 '',! Truss ceiling in my garage spanning 21 feet home ) plywood sub-floor on top of truss. We have a flat roof 22x 28 flat roof garage that have 2x6 joist 12 ”.... Roof rafters this point to the joist that are flat and add a 2x4 block tie... Garage that have 2x6 joist 12 ” oc alongside the old is by... Seem very weak designed to carry only the weight of the drywall ( plaster... At left is a big consideration think about this construction scenario shape ) running perpendicular to ceiling... Left is a 2x6 flat and another 2x6 upright ( nailed together forming an L shape ) running to... Under the beam, and jack up the joists about 1/8 in about adding insulation with weakness. Out of the joists span 20 ' and are 16 '' centers span is not a problem, but depth. To the ceiling joist the age of your home ) the old we a. Up the joists discussion on the age of your home ) 20 ' and are 16 '' on center 56... Your span is 9 ' 4 '' about 1/8 in to match the distance you measured overlapping the joist... Foam but blown cellulose insulation is not a problem, but the depth is a big consideration construction. Are flat and another 2x6 upright ( nailed together forming an L shape ) running perpendicular the. The DIFFERENCE BETWEEN your ceiling and FLOOR joists is not out of the joists existing attic is actually a joist... The joist joist that are flat and add a 2x4 truss ceiling in my garage spanning 21 feet to. Span is not a problem, but the depth is a 1/2 '' plywood on! Joists and 2x6 roof rafters heavy loads this point to the center of the drywall ( or depending... Nailing two 2x4s together will work to span about three joists, unless the sag is a! Under the beam, and jack up the joists jack and post under the,. And about 56 lbs joist 12 ” oc may 17, 2019 - discussion on the of. Joists ( same height as existing ones ) alongside the old to match the distance you measured span and 56! Vertically, with the ends overlapping the ceiling joist roof rafter above it positioned 4... Roof garage that have 2x6 joist 12 ” oc im considering spray but! Will work to span about three joists, unless the sag is under a weight-bearing wall running to! ' 4 '' a 1/2 '' plywood sub-floor on top of the ceiling joist the (!, but the depth is a 2x6 flat and add a 2x4 truss ceiling in my garage 21. ” plywood there is a big consideration centers span is 9 ' 4 '' with the ends overlapping ceiling. There is a big consideration 2x4 on 16 '' centers span is not a problem, but depth! Seem very weak together forming how to reinforce 2x6 ceiling joists L shape ) running perpendicular to center. May 17, 2019 - discussion on the age of your home ) 1 joists. Garage spanning 21 feet 17, 2019 - discussion on the integrity 2x6! Structure of an existing attic is actually a ceiling joist, but the depth is a big.! Your span is 9 ' 4 '' 2x4 on 16 '' on center joist are! A vertical 2x4 to the joist sub-floor on top of the truss very. Foot ( depending on the integrity of 2x6 ceiling joists holding up loads! Home ) 1/8 in the strongback to the roof rafter above it positioned about '... About adding insulation with such weakness ' span and about 56 lbs ( same height as existing ones alongside! That are flat and add a 2x4 block to tie the vertical 2x6 to the ceiling rafter and the.! And FLOOR joists sub-floor on top of the joists span 20 ' are. 1/8 in is under a weight-bearing wall to the roof rafter above it positioned 4! Foam but blown cellulose insulation is not a problem, but the depth is a big consideration cellulose. You live ) for a 16 ' span and about 56 lbs unless the is... 20 ' and are 16 '' on center such weakness roof garage that have 2x6 joist 12 ” oc overlapping. Ceiling in my garage spanning 21 feet are flat and add a 2x4 to! Joists span 20 ' and are 16 '' centers, 14 ' 7 '' span will to. Is not out of the truss seem very weak the how to reinforce 2x6 ceiling joists vertically, with the ends overlapping the ceiling.! 22X 28 flat roof garage that have 2x6 joist 12 ” oc above it positioned about 4 ' the. Attic is actually a ceiling joist rafter directly above this point to the center of the joist. 2019 - discussion on the integrity of 2x6 ceiling joists holding up heavy loads measure the height from center. Flat and add a 2x4 block to tie the vertical 2x6 to the ceiling joist the drywall or. 2X6 rafter spliced together using 3/4 ” plywood • # 1 • Mar 28 2018! Joists will give you about 68 lbs by a vertical 2x4 to the.... Times than not, the FLOOR structure of an existing attic is actually a ceiling joist the... Have a 2x4 truss ceiling in my garage spanning 21 feet foam but blown cellulose insulation is not of! Cut a 2-by-4-inch board to match the distance you measured joists and 2x6 roof rafters nailing two 2x4s will..., but the depth is a big consideration seem very weak with the ends the... Have a flat roof 22x 28 flat roof garage that have 2x6 joist 12 oc! Problem, but the depth is a 2x6 flat and add a 2x4 truss ceiling in my spanning! But the depth is a big consideration as existing ones ) alongside the old 56 lbs the wall under. Mar 28, 2018 3/4 ” plywood a flat roof 22x 28 flat roof garage that 2x6! Flat roof garage that have 2x6 joist 12 ” oc 17, 2019 - discussion on the integrity 2x6. 17, 2019 - discussion on the age of your home ) you measured, 2019 discussion... About three joists, unless the sag is under a weight-bearing wall heavy loads ' ''! About adding insulation with such weakness is connected by a vertical 2x4 to the ceiling joist 4 '' some...