# calculating exposed ceiling deck sq.ft?



## STAR

Was curious what percentage do you add to your sq.ft for the corrigated sections, joists and hvac ducts? I understand this could be different from job to job, but I need starting point. The ceiling I'm looking at is new and 3300 sq.ft.


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## Oden

Sixty gallons.


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## STAR

Oden said:


> Sixty gallons.


Care to elaborate? 

I have read depending on the size of the corregation _/\_/\_ you multiply your sq.ft by 1.5


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## jonathanthepainter

Material take off first, measure the sections, multiply, get total sq.footage. determine which material,how much primer, or finish, how many coats, figure access-height, mobilization costs. Time it would take you to do the job. Add. overhead and profit.


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## Oden

I count bays. A bay I figure for forty gallons. A bay is 2500 sq ft. You have to paint a bay and just shy of a half. I never had a mathematical equation. I just break Ceilongs down into bays and round off high.


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## bodean614

1.5 to 1.75. X sqft. Is a general range depending on size of joist and duct to be painted.


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## kmp

I add 35-40% of total square footage of the decking,and count bar joists as a solid beam not open space.No real formula but it has worked for me.


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## kmp

I also hate exposed structural steel in buildings.It's one thing in a warehouse but not in a retail bldg or grocery store.


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## KennedyEstimating

STAR said:


> Was curious what percentage do you add to your sq.ft for the corrigated sections, joists and hvac ducts? I understand this could be different from job to job, but I need starting point. The ceiling I'm looking at is new and 3300 sq.ft.


Plan X 2.75
3300 X 2.75=9075sf

I use 2.5 for deck and joist only.


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## STAR

kmp said:


> I add 35-40% of total square footage of the decking,and count bar joists as a solid beam not open space.No real formula but it has worked for me.


I was speaking with a local paint contractor that has done many of these types of ceilings and his method is basically the same as yours. He said calculate the sq.ft and then add 30% to your total. On new work he also cleans the hvac ducts with vinegar followed by water...no need to prime. Is that right?


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## bodean614

A lot of time the spec paint grip duct.


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## STAR

Okay here are some suggestions that have been discussed:

3300 sq.ft with no allowance of ducts, joist etc.

1. 3300 * 1.5 = 4950 sq.ft

2. 3300 * 40% = 4620 sq.ft

3. 3300 * 2.75 = 9075 sq.ft

The first two methods are close, but the last one seems very high!


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## bodean614

We paint a lot of d&j and the 1.5-1.75 always work for us. When I bid I will use 1.75 and when I order paint I use the 1.5 and always end up getting a few more gallons. A guy should put about 90 gallon a day


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## KennedyEstimating

STAR said:


> Okay here are some suggestions that have been discussed:
> 
> 3300 sq.ft with no allowance of ducts, joist etc.
> 
> 1. 3300 * 1.5 = 4950 sq.ft
> 
> 2. 3300 * 40% = 4620 sq.ft
> 
> 3. 3300 * 2.75 = 9075 sq.ft
> 
> The first two methods are close, but the last one seems very high!


To break the takeoff out "stick method" according to PDCA rules (see their Estimating Guide)
Since we don't know the layout/ deck size (depth profile) and joist spacing/layout. Here are my calculations.
I assume a 66' wide by 50' rectangular area to get your 3300sf.

Roof deck is not flat, the factors for the surface of deck vary from 1.1 sf/lf to over 2.5sf/lf depending on the profile. For this estimate we will use 1.33sf/lf as an average deck type profile. 
Deck = 66' x 50' = 3300sf x 1.33=4389sf

Josit- according to the PDCA, joist should be taken off as a flat surface (include both sides). We will assume 24" joist (a good average) at a spacing of 4' centers-
66' wide / 5'centers= 16.5 josits + 1 for the end= say 17 josts
17 josits X 50' long X 2 high (24") X 2 sides = 3400sf

X bracing, Usually roof joist have X bracing. This is a cross brace that runs perpendicular to the joists. PDCA rules say never use less than 1sf/lf for an item.
66' long (actually 93'long ea but I don't want to explain that here) X 2 ea X 3 runs = 66 X 2 X 3 = 396sf

So,
Deck = 4389sf
Joist = 3400sf
X Brace= 396sf
Total = 8185sf

Now the duct is a little more of a guess. I use 25% of plan area if I have no other details. 
3300sf X 25% = 825sf

8185 sf + 825 = 9010 sf
My original statement said to use a factor of 2.75/sf of plan for a total of 9075sf. That was not too far off from the "stick" takeoff I just showed you. Without a drawing, that is the best I can do. :thumbsup:


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## The Estimator67

KennedyEstimating said:


> To break the takeoff out "stick method" according to PDCA rules (see their Estimating Guide)
> Since we don't know the layout/ deck size (depth profile) and joist spacing/layout. Here are my calculations.
> I assume a 66' wide by 50' rectangular area to get your 3300sf.
> 
> Roof deck is not flat, the factors for the surface of deck vary from 1.1 sf/lf to over 2.5sf/lf depending on the profile. For this estimate we will use 1.33sf/lf as an average deck type profile.
> Deck = 66' x 50' = 3300sf x 1.33=4389sf
> 
> Josit- according to the PDCA, joist should be taken off as a flat surface (include both sides). We will assume 24" joist (a good average) at a spacing of 4' centers-
> 66' wide / 5'centers= 16.5 josits + 1 for the end= say 17 josts
> 17 josits X 50' long X 2 high (24") X 2 sides = 3400sf
> 
> X bracing, Usually roof joist have X bracing. This is a cross brace that runs perpendicular to the joists. PDCA rules say never use less than 1sf/lf for an item.
> 66' long (actually 93'long ea but I don't want to explain that here) X 2 ea X 3 runs = 66 X 2 X 3 = 396sf
> 
> So,
> Deck = 4389sf
> Joist = 3400sf
> X Brace= 396sf
> Total = 8185sf
> 
> Now the duct is a little more of a guess. I use 25% of plan area if I have no other details.
> 3300sf X 25% = 825sf
> 
> 8185 sf + 825 = 9010 sf
> My original statement said to use a factor of 2.75/sf of plan for a total of 9075sf. That was not too far off from the "stick" takeoff I just showed you. Without a drawing, that is the best I can do. 👍


K, I am looking at a project similar to the one discussed.
It has an area of 15, 386 sq feet.
2' high bar joist @ 4' on center.
No a/c duct work, on 5 a/c units with 4 vents directly below each unit.
Also has 4 structural beams that are 2.5' high x 113' wide each.
And of course there is sprinkler pipe & electrical conduit.
I am using a factor of 2.5 for a total square foot of 38,465.
How do I calculate the amount of materials?
My paint rep says 150 sq ft per gallon, I think 200 is more accurate.
What do you say?
I am figuring on using SW Procryl to prime everything and top coat with flat latex dry-fall.


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## Masterwork

Shouldn't need to prime anything, if it's all new construction. Just go straight to dryfall. Figure 50-100sq/ft per gallon, but you'll see once you actually start spraying. Don't buy all the paint at once, obviously.

Do the math, using the actual square footage of the floor. 15000/75 = 200 gallons or 40 five gallon pails.

No need to try to figure out the EXACT area of the ceiling, etc. It is worth working out the area of the beams, since each linear foot of beam actually has about 5-6 square feet of metal.

I will add, this is one of those things where having experience in spraying and applying the coating will save your ass come estimate time. You can literally do ALL the math, and figure out the EXACT surface area to be painted, but if you're blowing half the paint off into empty space due to a number of conditions, it really doesn't matter at all. It's better to know how much work you can do with one pail of paint, given the ceiling type. After hundreds of hours of spraying, that's how I know I can do 80sq/ft per gallon, with 3' open web joists, which is what most buildings use where I live. I also know I can do about 2000-2500sq/ft per day, depending on obstacles (like having to mask off an exterior wall), or just how lazy I'm feeling.


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## The Estimator67

The deck and bar joist may already have been shop primed.
Doing another site visit in the morning to verify with SW sales rep.
If that's the case, I will only need to prime raw sprinkler pipes.
Then shoot everything with flat dry-fall.....


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## The Estimator67

Site pics from 2 weeks ago.


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## Masterwork

The only thing to prime is the chunks of galvanized duct. No need to prime sprinkler pipes, either. Just wrap the sprinkler heads in tin foil, drape plastic over the lights (remove after spraying so you don't start a fire). Also, tell the electricians to put their cover plates on, or set them aside to be sprayed on the floor, before they install them.


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## The Estimator67

Thanks. I appreciate your input.


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