Calculating total weight of build?

Hi folks. I would like to add up all my building materials to find out if I'm within my floor's PSF. Are there any easy programs/spreadsheets to do that? ie: 32 2x4x8 studs, 21 sheets 1/4" plywood etc etc...and I want to input those numbers and also my size of build (sqft) and get the psf? thanks!

Steve was kind enough to post this on my thread. Just passing on the favor Weight of Standard Drywall panels - Regular Drywall Panels. To convert from PSF to kG/M^2 multiply PSF x 4.89 Panel Size /Weight /Lbs/SqFt /PCF /kG/M^3 4' x 8' x 3/8" = /45 lbs. /1.406 /42 /675 4' x 10' x 3/8" = /56 lbs. /1.406 /42 /675 4' x 12' x 3/8" = /67 lbs. /1.406 /42 /675 4' x 8' x 1/2" = /54 lbs. /1.6875 /42 /675 4' x 10' x 1/2" = /68 lbs. /1.6875 /42 /675 4' x 12' x 1/2" = /82 lbs. /1.6875 /42 /675 4' x 8' x 5/8" = /74 lbs. /2.3125 /42 /675 4' x 10' x 5/8" = /92 lbs. /2.3125 /42 /675 4' x 12' x 5/8" = /110 lbs. /2.3125 /42 /675 4' x 8' x 3/4" = /90 lbs. /2.81 /42 /675 Firecode Core Panels 4' x 8' x 5/8" = /70 lbs. /2.1875 /39.73 /638.5 4' x 10' x 5/8" = /88 lbs. /2.1875 /39.73 /638.5 4' x 12' x 5/8" = /105 lbs. /2.1875 /39.73 /638.5 Medium Density Hardboard – 43-60 PCF typical density, or 690-960 kG/m^3 To convert lb/cu ft into kG/m^3, multiply by 16.04. To convert the other way, divide by 16.04. Concrete weights approx. 3600 lbs/cu yd when cured, about 3900 pounds wet. 133 lbs/cu ft, or 2133 kG/M^3 - MDF - approx. 68 pounds per ½” 4x8 sheet or 2.125 PSF, 53 PCF, 850 kG/M^3 Glass = approx. 3.8 times weight per unit thickness of sheet rock - roughly 161 lbs for 4x8 sheet of 3/8” glass. The surface density of ¼” plywood is 0.74 lb/sq ft, or 23.68 pounds per 4’x8’ sheet. The surface density of 3/8” plywood is 1.11 lb/sq ft, or 35.5 pounds per 4’x8’ sheet. The surface density of ½” plywood is 1.48 lb/sq ft, or 47.36 pounds per 4’x8’ sheet. The surface density of 5/8” plywood is 1.85 lb/sq ft, or 59.18 pounds per 4’x8’ sheet. The surface density of ¾” plywood is 2.22 lb/sq ft, 71.04 pounds per 4’x8’ sheet, 35.5 PCF, 562.5 kG/M^3 A dry 8’ 2x4 weighs about 10 pounds, 2x6 about 15.7 pounds; density about 4.28 PSF for 2x lumber. This puts 2x lumber at roughly the same density as a layer of 5/8 and a layer of ½” drywall. 2x10 about 28 pounds per 8' length, or 3.5 lbs/lin.ft. – 2x10 framing on 24" centers adds approx. 2 lbs PSF dead load. 2x10 on 16" centers adds 2.7 PSF to dead load. 2x8 framing on 24" centers adds approx. 1.6 lbs PSF dead load. 2x8 on 16" centers adds 2.1 PSF to dead load. 2x6 framing on 24" centers adds approx. 1.2 lbs PSF dead load. 2x6 on 16" centers adds 1.6 PSF to dead load. Celotex has an average density of 16.8 PCF, or about 39% as dense as gypsum wallboard.

Holy cow! that's awesome!!! thank you thank you!!!

:?: Slightly confused now... Here's my situation. just as a calculation example ie: 8'x13' room (8' high) = 104sqft. 2 layers of 3/8" drywall (4x8) on inside walls and ceiling (we'll just work with the inside of the room, not the outside of the walls for now) = 27.5 sheets of 4x8 drywall... 27.5 x 45lbs(per sheet) = 1237.5 lbs total 1237.5 / 104sqft = 11.89 PSF right? but then in the post above, it also says that drywall weighs 1.406 PSF, so another calculation could be. 27.5 sheets of drywall x 1.406 psf = 38.665 PSF?!?! I'm sooo confused! help?

Rdolmat, You are looking at it slightly skewed Your ceiling is 104 square feet....two layers of 3/8 you will need approx 6 sheets. 270 pounds which is 2.59 PSF Now your walls are standing on end so you need the PSF where they sit which is 42 linear feet. Close enough to 20 sq ft of loaded floor space 18.5 sheets at 45 lbs. is about 41 PSF. Now if you are building a room within a room and are decoupling, all your weight from your ceiling will be on your walls. total weight 1100 lbs over 20 sq ft =55 PSF I came up with 440 sq ft of area to cover with rock. 25 sheets Tom

Thanks Tom!! So 55 PSF is my final total for the new room build? My new walls will actually be sitting on a new floor too, so would we still consider the walls as linear (even if the weight is distributed on the 104 sqft new floor?) This is the actual rating for my floors. I've been trying figure this out for months now...whether or not I can build a new room on these floors without crashing through and dying... Live Load 50 psf Partition 15 psf Dead Load 35 psf Not having much luck. I'm not a struc eng. I appreciate any help! cheers rich

Calculating the entire surface in square meters / feet for drywall should be no problem - simple math? Include all door / window areas to be on the safe side I'd say. Then calculate how many 2 X 4's that will be needed and so forth. For the record, my new recording area (only 4,3 x 4,1 meters) will way in abut 2000 kg! That's aprx. 114 kg/m2..a lot of weight

Lasso wrote:

Calculating the entire surface in square meters / feet for drywall should be no problem - simple math? Include all door / window areas to be on the safe side I'd say. Then calculate how many 2 X 4's that will be needed and so forth. For the record, my new recording area (only 4,3 x 4,1 meters) will way in abut 2000 kg! That's aprx. 114 kg/m2..a lot of weight

That's about 23 PSF...not too bad really. That's more what I thought I would be weighing in as...my dead weight PSF for the floor is 35, so we're good. And there's no way I'll get more than 50PSF live load either... And your room is actually bigger than mine...so why is my PSF calculation so skewed when compared to Tom's? When dividing the total weight of all the materials into the sqft, shouldn't we be using just the floor square footage to determine the PSF? So again. 13'lx8'wx8'h room 27.5 sheets drywall = 1237.5 lbs 350lbs plywood for floor area 42 2x3 = 420 lbs Studs, floor joists 10 2x6 = 160 lbs Ceiling joists 16"OC Total weight of build = 2167.5 lbs divided into floor sqft (for PSF Calculation) = 20.8 PSF total for the room.... The walls are resting on a floating floor, so I don't consider them linear as the weight of the walls and ceiling are spread over the 104 sqft footprint. Is this at all correct?! Are there any calculators online that I can punch in details of the materials and the sqft and it will spit out the PSF? Why is this so hard?!?!? :cry:

rdolmat, I stand corrected. I did not add any lumber into the calculations

When dividing the total weight of all the materials into the sqft, shouldn't we be using just the floor square footage to determine the PSF?

This is true but lets say you had a 500 pound computer and it only takes up 2 square feet of floor...you are at 250 pounds per square foot. So think of your walls in the same vein. Not to say your new floating floor wont help disperse the weight but I cant tell you how much. In other words I dont really know :o Tom

TomVan wrote:

rdolmat, I stand corrected. I did not add any lumber into the calculations

When dividing the total weight of all the materials into the sqft, shouldn't we be using just the floor square footage to determine the PSF?

This is true but lets say you had a 500 pound computer and it only takes up 2 square feet of floor...you are at 250 pounds per square foot. So think of your walls in the same vein. Not to say your new floating floor wont help disperse the weight but I cant tell you how much. In other words I dont really know :o Tom

Thanks Tom. I appreciate the help...I'm still delaying my build because I haven't heard back from 3 struc eng I've emailed regarding the floor potentially crashing down. Would 8' (2x4) ceiling studs hold 1 layer 3/8" drywall? I'm trying to lower the weight of the ceiling and walls. Or maybe I should ask, how much drywall can 2x4 (8' span) ceiling joists hold?

The local "building authorities" has approved of my build. The ceiling is 2 x 4''s spaced 24" centers, around 12 foot span with two layers of drywall (13mm each layer) attached.

Lasso wrote:

The local "building authorities" has approved of my build. The ceiling is 2 x 4''s spaced 24" centers, around 12 foot span with two layers of drywall (13mm each layer) attached.

Wow! I was thinking we'd need 2x6 min for ceiling joists. So, basically you're hanging two layers of drywall on 2x4 24"OC and the city said "sure no problem". So I guess the ceiling's not going to fall on anyone? Sorry for my paranoia. I just want to be triple sure of safety.

Yes. But better safe than sorry always! But hey, I have had 2 independent engineers and the local authorities approve the construction so it should be ok. But always double check. Here are the plans we're working after in case you're curious. I'm posting the measures again in metric to be sure we're not misunderstanding each other: Ceiling is build using 45 x 95 mm joists spaced 60 cm centers. They span 4,1 meters. We might attach some short pieces of 45 x 95 between the joists to make it more rigid. But if you do the math you'll find out that each joist actually doesn't carry THAT much weight:)

Lasso wrote:

Yes. But better safe than sorry always! But hey, I have had 2 independent engineers and the local authorities approve the construction so it should be ok. But always double check. Here are the plans we're working after in case you're curious. I'm posting the measures again in metric to be sure we're not misunderstanding each other: Ceiling is build using 45 x 95 mm joists spaced 60 cm centers. They span 4,1 meters. We might attach some short pieces of 45 x 95 between the joists to make it more rigid. But if you do the math you'll find out that each joist actually doesn't carry THAT much weight:)

Thanks Lasso! I did the conversions to inches, and we're on the same page. You're right though, if you really think about it. 1 peice of 3/8 drywall weighs 45lbs (20kg). If I go 16"OC then each 2x4 only has to carry 15 lbs. 30lbs if using two layers drywall. I'm sure the joists can handle that!

UPDATE! We've finished framing, and with a span of 4,1 meters we've decided to ad a support beam. You should do the same;) The support beam was made using two 2 x 4's screwed together, and put, obviously, on top of the roof joists, on a 90 degree angle relative to the joists.

Lasso wrote:

UPDATE! We've finished framing, and with a span of 4,1 meters we've decided to ad a support beam. You should do the same;) The support beam was made using two 2 x 4's screwed together, and put, obviously, on top of the roof joists, on a 90 degree angle relative to the joists.

ooops.! Was that an engineer's suggestion? Thanks for the update. Basically you put two 2x4 peices (screwed together) across the top of your ceiling joists (at a 90 degree angle). And you just screwed these down with 5inch screws to the to of the ceiling joists? Or would stringers in between the joists work as well/better? cheers rich

Basicly we just realized that we had enough spare wood left to build it and so we did. It did wonders stabilizing the roof construction! Remember, that this is before drywall is put up which will make the construction even more rigid. But we did it to be on the safe side...not because the structure would not be able to hold the 2 layers of drywall, but because the roof joists had a tendancy to bend down a litle. And that wouldn't look nice;) The support beam was put on top of the "existing" roof joist, right in the middle at an 90 degree angle (on the high side ofcourse), resting on the outer wall joist. See? I'll post some pictures later...(and probably get flamed to pieces hahahaha)

ha ha!! Thanks Lasso! I'm looking forward to it!

here we go: Basic framing using 45 x 95 mm joists - to the left my dad and chief engineer, to the right Jens, my studio partner. You can see a litle of how the floor is built: neoprene pucks, joist on high, 2 layers of "floor board" Starting on the roof framing...Jens doing nothing More roof framing Framing in progress - first door about to be put in - an exiting moment:) Even more wall and roof framing - notice how the roof joists are put directly above the wall joists to distribute the weight on the wall joists instead of the top vertical joist. The support beam of death! Notice how the support beam ofcourse does NOT touch the existing roof. When the drywall is put up, the entire structure will settle even more on the neopren pads, creating a bigger gap to the existing roof. Another shot of the support beam, showing how it's mounted to the floor joists. The brackets were put a couple of milimeters under the support beam, so the beam is pulled towards the roof joists when the screws come in :D

Nice pics!! Thanks so much! Looking good! It's always great to have Dad around to tell you what you're doing wrong. That will be my situation too. :wink: although he loves it 'cause he's retired anyway. PS:Tell Jens to get to work! :twisted: