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SPFer Posted: Feb 18, 2010 05:55 PM	Yield over Concrete I am bidding a parking garage in the Northeast. We are spraying the concrete ceiling of the garage, sometime after April. We will be putting up temporary, plastic walls and can throw our big heater in the enclosure to heat it up. However, I know cement is hard as hell to heat up. What should I account for loss in yield? I was thinking 10%, so I would figure we'd get 4,000 bd ft out of one 5,000 bd ft set.
mason Posted: Feb 18, 2010 07:53 PM	You might get 10 to 15 percent loss of yield with colder temperatures. Below a certain temperature you should not spray. (typically substrates below 50 degrees) But there are cold weather formulas that might get you better yields in colder temperatures. Check with your supplier for their opinions and the yields of the foam in various climates and substrates.
Terry Adams Posted: Feb 18, 2010 10:21 PM	what brand are you getting 5000bf out of. like to try that one out.
SPFer Posted: Feb 20, 2010 08:21 AM	We're spraying Lapolla. Get around 5,000 bd ft.
richard sucher II Posted: Feb 20, 2010 07:34 PM	Assuming that 60 degrees is optimum, we would allow 10% loss for substrate temp of 50 degrees. It has not been our experience to get 5000 bd. ft. out of a set of two pound closed cell foam. At best , we would use 4500 bd. ft. as yield on a set weighing 1050 pounds. 4000 board feet per set makes more sense to us at 50 degrees. We disagree on the starting point that you use of 5000 board feet per set. Good luck on the job bid.
Posted: Feb 22, 2010 04:32 AM	...right on caddis,, if its yieldin 5000 its gots to be 1.7 or there abouts,,, not sure on the compressive strength of 1.7 but 2lb far exceeds the 2" boardstock,,, use 3500 for your yeild estimate and you wont get burned,,too bad,,specially when its cold..you may even make some $$$
Posted: Feb 25, 2010 10:32 PM	What thickness are you going? That will play a part, as your first lift will see the greatest loss in yield.
mason Posted: Feb 26, 2010 10:41 AM	Sprayfoam1 makes a good point. On colder substrates you can get better yield by installing your first lift at 0.5 to 0.75 inches. Check adhesion to the substrate and then you can install thicker lifts (after letting the foam exothermic heat dissipate) The first layer of foam insulates the surface so the next lift of foam comes up with a better yield. Be sure not to go over 1.5 inches per lift unless you are sure the foam can handle it without exhibiting poor physical properties such as too many open cells, low compressive strength, etc.

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Comments

SPFer

Posted: Feb 18, 2010 05:55 PM

Yield over Concrete

I am bidding a parking garage in the Northeast. We are spraying the concrete ceiling of the garage, sometime after April. We will be putting up temporary, plastic walls and can throw our big heater in the enclosure to heat it up. However, I know cement is hard as hell to heat up. What should I account for loss in yield? I was thinking 10%, so I would figure we'd get 4,000 bd ft out of one 5,000 bd ft set.

mason

Posted: Feb 18, 2010 07:53 PM

You might get 10 to 15 percent loss of yield with colder temperatures. Below a certain temperature you should not spray. (typically substrates below 50 degrees) But there are cold weather formulas that might get you better yields in colder temperatures. Check with your supplier for their opinions and the yields of the foam in various climates and substrates.

Terry Adams

Posted: Feb 18, 2010 10:21 PM

what brand are you getting 5000bf out of.
like to try that one out.

SPFer

Posted: Feb 20, 2010 08:21 AM

We're spraying Lapolla. Get around 5,000 bd ft.

richard sucher II

Posted: Feb 20, 2010 07:34 PM

Assuming that 60 degrees is optimum, we would allow 10% loss for substrate temp of 50 degrees. It has not been our experience to get 5000 bd. ft. out of a set of two pound closed cell foam. At best , we would use 4500 bd. ft. as yield on a set weighing 1050 pounds. 4000 board feet per set makes more sense to us at 50 degrees. We disagree on the starting point that you use of 5000 board feet per set. Good luck on the job bid.

Posted: Feb 22, 2010 04:32 AM

...right on caddis,,
if its yieldin 5000 its gots to be 1.7 or there abouts,,,
not sure on the compressive strength of 1.7 but 2lb far exceeds the 2" boardstock,,,

use 3500 for your yeild estimate and you wont get burned,,too bad,,specially when its cold..you may even make some $$$

Posted: Feb 25, 2010 10:32 PM

What thickness are you going? That will play a part, as your first lift will see the greatest loss in yield.

mason

Posted: Feb 26, 2010 10:41 AM

Sprayfoam1 makes a good point.

On colder substrates you can get better yield by installing your first lift at 0.5 to 0.75 inches. Check adhesion to the substrate and then you can install thicker lifts (after letting the foam exothermic heat dissipate)

The first layer of foam insulates the surface so the next lift of foam comes up with a better yield.

Be sure not to go over 1.5 inches per lift unless you are sure the foam can handle it without exhibiting poor physical properties such as too many open cells, low compressive strength, etc.

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