insulation question

[yetisas]

Hey all
Need some suggestions for the insulation of the ceiling of my 44 x 30 x 10 workshop. Normally I wouldn't have an issue if the ceiling joists were running vertical I'd just put in the r-19 with vapor barrier and let the ridge vent and soffit vents do their thing. But my ceiling joists are on the horizontal 24 oc. I'm not sure if I'd get enough air moving from front to back over the 44' length. I could I guess drill a million holes in the joists so air can move from bottom to top. Or would it be best to completely fill up the void between the joists and not have any air movement? What do you all think s/b my plan of attack? Thanks

 

[Kevin54]

Not sure if I am understanding the question but most ceiling joist do run horizontal. Do you not have soffits that are vented? If so, then you put the plastic tray up against the roof sheathing that lets air flow then **** the insulation up against it. You will need adequate vents on the roof for the size of the building though. But if your soffits are vented along with a ridge vent, you should be fine. You could also cut in a couple of gable end vents for added air flow.

 

[yetisas]

Well I'll see if i can explain better. Normally with trusses the airflow goes from bottom of the roof to the top ridge vent on the roof(like in an attic space). Mine is different in that it's an open ceiling that has metal trusses every 10 feet with 2 x 8 purlins (I'd guess you call them which gives me a clear span between the walls)attached horizontally to the metal trusses and the roof deck is nailed to the 2 x 8 purlins. The area I'm trying to insulate is between the purlins which are running from the front of the building to the back thus there isn't airflow from the bottom of the roof to the ridge vent it's from side to side so if I put vented soffit on the full length of the gable ends I don't think I'll get enough airflow through the 44' length of the building(to avoid moisture problems). I'm trying to figure out if I should fill the cavities completely with no airflow or drill holes in the purlins to get the airflow effect of normal roof trusses from bottom to top??
Not sure if I'm explaining correctly?

 

[padstack]

Can you afford spray in foam? My understanding is that it doesn't need air movement. Someone will correct me if I'm wrong though.