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William Gibson Posted: Jul 26, 2011 07:32 AM	Roof Crickets Mason: working on a bid for a roof. Have a low-sloping roof that slopes down to a portion of the building that is taller than the roof deck. The building was an after-thought and obviously roof drainage wasn't thought about. The building spans 24' of the roof. Looking to build a cricket to keep the water to the right and left of the building. Do you find it easier to make a site-built cricket, buy a pre-built cricket, or build up the SPF to form a cricket?
mason Posted: Jul 26, 2011 08:27 AM	It is easier to spray in crickets, not to mention that it would be an integral part of the roof and not another mechanically fastened assembly that could be a source of problems later on. The technique takes some practice. You want to start by spraying the center of the cricket first in the shape you want, then spray another layer of foam just slightly larger on the next pass and continue until you have the cricket the size required. Spray the foam in 0.5 inch lifts and make sure to let it cool before installing the next pass to prevent too much exothermic heat from developing. Try practicing on the ground first until you feel comfortable with the shape and size.
richard sucher II Posted: Jul 26, 2011 01:34 PM	For what it is worth, these crickets need to be at least 1/2"/foot fall to be effective in my opinion. Spraying crickets can be problematic and the results can be uneven. I would buy tapered foam panels specifically designed to meet the roof conditions and either mechanically attach them or set them in low rise foam adhesive. Then spray your foam roof over the tapered crickets.
William Gibson Posted: Jul 27, 2011 06:49 AM	cobb: Thanks for the response. Any place in particular where pre-fab crickets are available? Did a google search but came up with minimal results.
Posted: Jul 27, 2011 09:38 AM	Newman Mason is correct. It is very simple to spray a cricket. One question though, do you need a cricket for a penetration or do you need to taper a roof to force water in different directions?
richard sucher II Posted: Jul 27, 2011 09:55 AM	My suggestion that you use precut tapered iso pieces is based on your comment that you do not have experience in spraying these types of details. Crickets can be sprayed by experienced applicators. If you are tearing off existing roofing materials down to deck, spraying in crickets can be more foregiving. If it is a reroof over existing irregular surface, spraying in crickets can be more problematic as surface makes it more difficult to get water to flow positively. Precut tapered pieces can be purchased from any commercial roofing supply house such as ABC Supply, etc. Just need to give distributor drawing of existing roof dimensions and location of scuppers/drains etc where water is to flow. Depending on existing slope of roof, estimator can work with you to design tapered system with adequate flow. Starting level is usually one half inch and can slope typically 1/4" to 1/2"/foot. If price is an issue, you can use expanded polystyrene for tapered pieces but beware that density of poly is low and this starting pieces break easily, therefore I use iso. Good luck.
William Gibson Posted: Jul 27, 2011 11:21 AM	We have several years of spraying experience. Mostly wall/interior and air barrier applications. Done a half-dozen flat roofs. Crickets have not been needed on the roofs we've already sprayed. Because we have not dealt with crickets I wanted to get some input to see what is typically used. We will likely spray in the crickets. When the guys get back from a project early we'll lay out the 4-mil on the shop floor and do a test or two. It is only to divert the water around the building for proper run-off to a lower roof.
Posted: Jul 27, 2011 02:38 PM	Cobb is right. It really depends upon your experience. If you taper horizontal to the edge of the roof where you want water to go and you have pass line bumps to your right and left, you will trap water to the middle of your pass. If you want to maintain a flat spray on a tapered spray foam system, put your temps to where when the foam hits the roof it sort of looks the color of Coco Cola hitting the ground when you spill it before it starts to rise and turns white. If it takes 5-10 seconds to begin to rise, then you are to cold. It should be just a second or so after it hits the deck. If it is white coming out of the gun like some of the wall foamers like to spray, god help you trying to keep it smooth. There is something about roofing foam when it is a little cooler (115 on A and 125 on B summertime right now) that allows it to lay out flatter and makes pass lines invisible. Right now, I have to turn off my hose heat to keep it under 140 on the roof with the heat. If your foam is white coming out of the gun, you will look like a Rookie, even if your not. Pay attention to your temps and how the foam lays down and a tapered system will be easy. 1/8" on 12 will do the trick, 1/2" on 12" is better, but since you are bidding on it, you may be high if everyone else is basing off of 1/8" on 12".

Author

Comments

William Gibson

Posted: Jul 26, 2011 07:32 AM

Roof Crickets

Mason: working on a bid for a roof. Have a low-sloping roof that slopes down to a portion of the building that is taller than the roof deck. The building was an after-thought and obviously roof drainage wasn't thought about. The building spans 24' of the roof.

Looking to build a cricket to keep the water to the right and left of the building.

Do you find it easier to make a site-built cricket, buy a pre-built cricket, or build up the SPF to form a cricket?

mason

Posted: Jul 26, 2011 08:27 AM

It is easier to spray in crickets, not to mention that it would be an integral part of the roof and not another mechanically fastened assembly that could be a source of problems later on.

The technique takes some practice. You want to start by spraying the center of the cricket first in the shape you want, then spray another layer of foam just slightly larger on the next pass and continue until you have the cricket the size required. Spray the foam in 0.5 inch lifts and make sure to let it cool before installing the next pass to prevent too much exothermic heat from developing.

Try practicing on the ground first until you feel comfortable with the shape and size.

richard sucher II

Posted: Jul 26, 2011 01:34 PM

For what it is worth, these crickets need to be at least 1/2"/foot fall to be effective in my opinion. Spraying crickets can be problematic and the results can be uneven. I would buy tapered foam panels specifically designed to meet the roof conditions and either mechanically attach them or set them in low rise foam adhesive. Then spray your foam roof over the tapered crickets.

William Gibson

Posted: Jul 27, 2011 06:49 AM

cobb:
Thanks for the response. Any place in particular where pre-fab crickets are available? Did a google search but came up with minimal results.

Posted: Jul 27, 2011 09:38 AM

Newman

Mason is correct. It is very simple to spray a cricket.

One question though, do you need a cricket for a penetration or do you need to taper a roof to force water in different directions?

richard sucher II

Posted: Jul 27, 2011 09:55 AM

My suggestion that you use precut tapered iso pieces is based on your comment that you do not have experience in spraying these types of details. Crickets can be sprayed by experienced applicators.
If you are tearing off existing roofing materials down to deck, spraying in crickets can be more foregiving. If it is a reroof over existing irregular surface, spraying in crickets can be more problematic as surface makes it more difficult to get water to flow positively.
Precut tapered pieces can be purchased from any commercial roofing supply house such as ABC Supply, etc. Just need to give distributor drawing of existing roof dimensions and location of scuppers/drains etc where water is to flow. Depending on existing slope of roof, estimator can work with you to design tapered system with adequate flow.
Starting level is usually one half inch and can slope typically 1/4" to 1/2"/foot. If price is an issue, you can use expanded polystyrene for tapered pieces but beware that density of poly is low and this starting pieces break easily, therefore I use iso. Good luck.

William Gibson

Posted: Jul 27, 2011 11:21 AM

We have several years of spraying experience. Mostly wall/interior and air barrier applications. Done a half-dozen flat roofs. Crickets have not been needed on the roofs we've already sprayed.

Because we have not dealt with crickets I wanted to get some input to see what is typically used. We will likely spray in the crickets. When the guys get back from a project early we'll lay out the 4-mil on the shop floor and do a test or two.

It is only to divert the water around the building for proper run-off to a lower roof.

Posted: Jul 27, 2011 02:38 PM

Cobb is right. It really depends upon your experience. If you taper horizontal to the edge of the roof where you want water to go and you have pass line bumps to your right and left, you will trap water to the middle of your pass.

If you want to maintain a flat spray on a tapered spray foam system, put your temps to where when the foam hits the roof it sort of looks the color of Coco Cola hitting the ground when you spill it before it starts to rise and turns white. If it takes 5-10 seconds to begin to rise, then you are to cold. It should be just a second or so after it hits the deck.

If it is white coming out of the gun like some of the wall foamers like to spray, god help you trying to keep it smooth.

There is something about roofing foam when it is a little cooler (115 on A and 125 on B summertime right now) that allows it to lay out flatter and makes pass lines invisible. Right now, I have to turn off my hose heat to keep it under 140 on the roof with the heat.

If your foam is white coming out of the gun, you will look like a Rookie, even if your not. Pay attention to your temps and how the foam lays down and a tapered system will be easy. 1/8" on 12 will do the trick, 1/2" on 12" is better, but since you are bidding on it, you may be high if everyone else is basing off of 1/8" on 12".

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