Post frame finishing question - soffit venting

[Low50s]

Hey everyone I have tried to use the search and have seemed to come up empty handed.

I recently had my 30x40x14 constructed and I am wanting to finish the inside with tin also but am having a dilemma with how to vent my soffits. I have looked at baffles but I can only find for 24"oc max could I use that foil bubble insulation and build a baffle ? Or what does everyone think ?

Also when I run purlins for the bottom chord how would everyone recommend doing so ?

Strong ties and cut to keep them at bottom chord height or just attach 2x4 across the bottom and use blow in cellulose and call it a day ? Thanks for the help attached are some pictures

 

[blair683]

Your building is by far not designed with the intent to finish the inside. I recently built a more traditional pole building. I put my trusses on 24" centers knowing that I would eventually finish the ceiling. Your "soffit vent" looks to be lower then the bottom chord of your trusses. Are your trusses spaced 8' apart? Maybe the way your building is designed is more common for your location. It's the first time I have seen one built like that. I am guessing you would have to run your purlins in between the bottom chords with joist hangers. I think you would get a lot of sag If you just screw 2"x4"s flat against the bottom chords across an 8' span. Especially with insulation on top of them.

 

[keen]

I recently had my 30x40x14 constructed and I am wanting to finish the inside with tin also but am having a dilemma with how to vent my soffits. I have looked at baffles but I can only find for 24"oc max could I use that foil bubble insulation and build a baffle ? Or what does everyone think ?

I'm confused what insulation and baffles have to do with soffits? the soffit is outside - which you dont show (the underside of the eave). Are they enclosed now? External vents should probably be on the bottom face..

You may choose to vent them into your "attic" if you're going to finish the attic.

You can use vented closure strips between the roof metal and the wood (these have meshy vents in the ribs) - but those were best installed as the root was installed. If you're going to close the attic, and soffit the eaves, I'd just let the attic get its vent from the ribs themselves.

If you really feel the need for more eave > attic connection than the ribs provide, you could drill holes in that top of wall purlin and screen over them. the only structure it supports is that section of roof sitting on top of it. There are even "standards" out there for drilling purlin for venting out there somewhere if you dig a bit.

Also when I run purlins for the bottom chord how would everyone recommend doing so ?

Strong ties and cut to keep them at bottom chord height or just attach 2x4 across the bottom and use blow in cellulose and call it a day ? Thanks for the help attached are some pictures

Note that you -can- just finish the ceiling at the roof purlins if you want, and insulate it above that ceiling. (make sure you maintain vent - which the ribs provide across the purlins through to the peak vent)

If you want to enclose the attic space and put a flat ceiling at the bottom chord of the truss, I'd probably do hang 2x 24" OC with joist hangers....probably 2x6 or 2x8 depending. If you're using metal, it depends which way you run the ribs - if you want to run the ribs long way, I'd treat it closer to how I would for drywall: I'd then run 1x3 strapping across those 24" to provide a flat surface with a drywall friendly spacing. or metal friendly (so 24" would probably be OK - even 48 if the ribs are working in your favor, depending on the metal)

It's worth noting that the ceiling supports are not purlins. purlins support roof. girt support walls. in post frame terms, I dont think there's a name for the ceiling structure.


I'd remove that open mesh at the top of the wall and close that with metal outside - if your soffits are already enclosed, I'm assuming that connects to them?? No idea what someone was thinking there.


As for the other construction details - those are typical trusses for post frame (1 truss, or a pair of trusses, per post). because of the need for purlins (even if you ran trusses at 24 or 16 OC you'd still have to strap or purlin the top) with rib metal, you're really wasting trusses doing it that way (and you have to beef up your supports between posts to carry them..)

It's good that there's a fair amount of diagonal bracing in the walls, since those posts are NOT posts - and they are not in the ground, but bolted to the floor. You lose all of the structural sheer strength advantages without embedment.

 

[blair683]

But with 24" on center trusses sitting on a double header. Your ceiling would have been much easier to finish and easier/ cheaper to insulate. I assumed that you are calling that screened wall vent a "soffit vent". A picture of the outside of the building would probably help out here.

 

[Low50s]

Your building is by far not designed with the intent to finish the inside. I recently built a more traditional pole building. I put my trusses on 24" centers knowing that I would eventually finish the ceiling. Your "soffit vent" looks to be lower then the bottom chord of your trusses. Are your trusses spaced 8' apart? Maybe the way your building is designed is more common for your location. It's the first time I have seen one built like that. I am guessing you would have to run your purlins in between the bottom chords with joist hangers. I think you would get a lot of sag If you just screw 2"x4"s flat against the bottom chords across an 8' span. Especially with insulation on top of them.

I told the builder the plan was to finish and he said it could be finished when built.

Yes trusses are 8'OC I was debating on flat vs joist hangers yes the vent is lower than the bottom chord which is odd and I have never seen anything like it before

Yes I have 1' overhangs on the building also sorry I'm trying to type everything on cell phone so hope it all makes sense

 

[Low50s]

I'm confused what insulation and baffles have to do with soffits? the soffit is outside - which you dont show (the underside of the eave). Are they enclosed now? External vents should probably be on the bottom face..

You may choose to vent them into your "attic" if you're going to finish the attic.

You can use vented closure strips between the roof metal and the wood (these have meshy vents in the ribs) - but those were best installed as the root was installed. If you're going to close the attic, and soffit the eaves, I'd just let the attic get its vent from the ribs themselves.

If you really feel the need for more eave > attic connection than the ribs provide, you could drill holes in that top of wall purlin and screen over them. the only structure it supports is that section of roof sitting on top of it. There are even "standards" out there for drilling purlin for venting out there somewhere if you dig a bit.




Note that you -can- just finish the ceiling at the roof purlins if you want, and insulate it above that ceiling. (make sure you maintain vent - which the ribs provide across the purlins through to the peak vent)

If you want to enclose the attic space and put a flat ceiling at the bottom chord of the truss, I'd probably do hang 2x 24" OC with joist hangers....probably 2x6 or 2x8 depending. If you're using metal, it depends which way you run the ribs - if you want to run the ribs long way, I'd treat it closer to how I would for drywall: I'd then run 1x3 strapping across those 24" to provide a flat surface with a drywall friendly spacing. or metal friendly (so 24" would probably be OK - even 48 if the ribs are working in your favor, depending on the metal)

It's worth noting that the ceiling supports are not purlins. purlins support roof. girt support walls. in post frame terms, I dont think there's a name for the ceiling structure.


I'd remove that open mesh at the top of the wall and close that with metal outside - if your soffits are already enclosed, I'm assuming that connects to them?? No idea what someone was thinking there.


As for the other construction details - those are typical trusses for post frame (1 truss, or a pair of trusses, per post). because of the need for purlins (even if you ran trusses at 24 or 16 OC you'd still have to strap or purlin the top) with rib metal, you're really wasting trusses doing it that way (and you have to beef up your supports between posts to carry them..)

It's good that there's a fair amount of diagonal bracing in the walls, since those posts are NOT posts - and they are not in the ground, but bolted to the floor. You lose all of the structural sheer strength advantages without embedment.

I plan on running metal and with the way my ribs are going they will be working in my favor I was thinking of 36" spacing but I could easily run 24" and thanks for the clarification on girt/purlin I want to close in the attic then I won't see the trusses on the building and I have a nice surface to run electric on

 

[keen]

I plan on running metal and with the way my ribs are going they will be working in my favor I was thinking of 36" spacing but I could easily run 24" and thanks for the clarification on girt/purlin I want to close in the attic then I won't see the trusses on the building and I have a nice surface to run electric on

Note that if you (or anyone else) ever need to crawl inside that attic, closer is better than further, even though it costs more up front... trying to straddle a 36" ceiling joist spacing would be Fun.

Might be worth laying down some plywood even if it's just a 24" end-to-end crawl path down the center, to make future maintenance easier, as the ceiling goes up.

 

[Low50s]

Note that if you (or anyone else) ever need to crawl inside that attic, closer is better than further, even though it costs more up front... trying to straddle a 36" ceiling joist spacing would be Fun.

Might be worth laying down some plywood even if it's just a 24" end-to-end crawl path down the center, to make future maintenance easier, as the ceiling goes up.

Ya I was planning on taking like a 2x12 or something similar and putting that from end to end along with two attic access doors about 10' from my end walls being that I am 40 wide I could hopefully be able to be no more than 10' from any corner (in a perfect world)