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philip mullins Posted: Sep 04, 2007 11:01 AM	remove the vents? i just got a call for a 100 year old home with a new metal roof. customer converted the attic space into bedrooms and is searching for a way to cool things down a bit. he is interested in applying foam to yhe underside of the roof, wich is becoming quiet common down here in the deep south. client told me that he just had a roof vent installed along the peak of the roof. my question is this, if we foam the underside of the roof, should i do away with that vent? since the home is insulated conventionaly and 100 years old i dont think that an unvented attic system would be very beneficial(?). but, i dont think that leaving a 'hole' in the middle of the area i am tryin to insulate would be a good idea either. any reccomendations?
mason Posted: Sep 04, 2007 05:59 PM	Venting the attic or the roof defeats the benefits of the sprayfoam and allows hot humid air to entry the attic. Close off the vent if you spray to the underside of the roof deck. This will prevent the attic from getting hot in the summer and cold in the winter. The building will be much more comfortable and you can count on significant energy savings.
philip mullins Posted: Sep 05, 2007 11:06 AM	ok, i met with the guy this morning and looked at the job.its gonna be a nightmare just to get to all the areas that need to be sprayed. i guess thats why they call it work. the only remaining questions i have left are, first, he wants to leave the metal vents in the soffit and have me foam over them so that he doesnt have to redo the soffit and repaint. i was thinking about taking them down and duct taping them from the inside. then foaming over them. would that work? and last but not least, what is the cheapest ignition barrier i can use in the attic. i dont know if this guy is gonna go with foam or not so i dont wannaadd any more cost than neccesary. but, hes gotta do something. he has absolutely no insulation up thier at all. sry for the dumb questions mace. i am still a newbie and have never tackled a project like this before. and i realy wanna do a good job.
Gerry Wagoner Posted: Sep 05, 2007 01:54 PM	Hi Trout. You can use a number of materials over the vents to act as a slipsheet barrier to spray to. Duct tape, cardboard, cheap luan board or paneling. Anything that will prevent foam from extruding through the vents. As to the vents, yes. Just pack them with something and foam them closed. If they are small, the foam itself should seal them off. Have fun and keep your head down. :) oG
mason Posted: Sep 06, 2007 04:49 PM	I like Olger's idea on the vents. The cheapest ignition barrier is 1-1/2" of fiberglass or rockwool. Don't use the kraft faced stuff, it is not an ignition barrier. Staple right over the foam. Intumescent coatings may be used if they have been specifically tested and approved by ICC Evaluation Services over the foam you are using in the same type of application.

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philip mullins

Posted: Sep 04, 2007 11:01 AM

remove the vents?

i just got a call for a 100 year old home with a new metal roof. customer converted the attic space into bedrooms and is searching for a way to cool things down a bit. he is interested in applying foam to yhe underside of the roof, wich is becoming quiet common down here in the deep south. client told me that he just had a roof vent installed along the peak of the roof. my question is this, if we foam the underside of the roof, should i do away with that vent? since the home is insulated conventionaly and 100 years old i dont think that an unvented attic system would be very beneficial(?). but, i dont think that leaving a 'hole' in the middle of the area i am tryin to insulate would be a good idea either. any reccomendations?

mason

Posted: Sep 04, 2007 05:59 PM

Venting the attic or the roof defeats the benefits of the sprayfoam and allows hot humid air to entry the attic. Close off the vent if you spray to the underside of the roof deck. This will prevent the attic from getting hot in the summer and cold in the winter. The building will be much more comfortable and you can count on significant energy savings.

philip mullins

Posted: Sep 05, 2007 11:06 AM

ok, i met with the guy this morning and looked at the job.its gonna be a nightmare just to get to all the areas that need to be sprayed. i guess thats why they call it work. the only remaining questions i have left are, first, he wants to leave the metal vents in the soffit and have me foam over them so that he doesnt have to redo the soffit and repaint. i was thinking about taking them down and duct taping them from the inside. then foaming over them. would that work? and last but not least, what is the cheapest ignition barrier i can use in the attic. i dont know if this guy is gonna go with foam or not so i dont wannaadd any more cost than neccesary. but, hes gotta do something. he has absolutely no insulation up thier at all.

sry for the dumb questions mace. i am still a newbie and have never tackled a project like this before. and i realy wanna do a good job.

Gerry Wagoner

Posted: Sep 05, 2007 01:54 PM

Hi Trout.

You can use a number of materials over the vents to act as a slipsheet barrier to spray to.

Duct tape, cardboard, cheap luan board or paneling. Anything that will prevent foam from extruding through the vents.

As to the vents, yes. Just pack them with something and foam them closed. If they are small, the foam itself should seal them off.

Have fun and keep your head down. :)

oG

mason

Posted: Sep 06, 2007 04:49 PM

I like Olger's idea on the vents. The cheapest ignition barrier is 1-1/2" of fiberglass or rockwool. Don't use the kraft faced stuff, it is not an ignition barrier. Staple right over the foam. Intumescent coatings may be used if they have been specifically tested and approved by ICC Evaluation Services over the foam you are using in the same type of application.

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