how should I have vaulted ceiling insulated?

[madmaxnj]

I am still in the planning stages for my 24x32x12 garage. Just a hobbyist garage to store my toys and work on them. Eventually will have a 2 post, and much later will store a motorhome. I am looking to have scissor trusses to maximize interior height, as exterior height is frowned upon (need a variance as it is). 4/12 pitch roof on the outside, 2/12 pitch on the inside. I’m looking at builders to do the basics, but then I’ll do some of the finish work. So builder will do foundation, structure, doors/windows, electrical panel, and ceiling/ceiling insulation. Later on I will run electrical in the walls, insulate the walls, and sheath the walls. I am planning on OSB for the entire interior, all screwed in. This allows me to drop sheets if I need to get in the walls for anything. I’d probably paint it all too for light reflection, but I’m not looking for it to look like the inside of a house, it’s a garage after all. I figure I’d run all the electrical in the walls, and mount a series of high mounted outlets off a switch for lighting, maybe 1 or 2 banks. And then I can just hang lights from the ceiling OSB and run the cords to the high outlets on the walls. Not high tech but gets the job done.

Since I'll want the basic work structure to go up as quickly as possible and get ready for me to get working in there, I'll have the builder insulate and put up the ceiling. Working by myself that would just take forever and I'd have to buy or rent some lifts and other stuff to do it all by myself. Doing wall work and hanging lights and fans and whatnot by myself is much more reasonable.

I am in northern NJ, so think 20s-30s in the winter and 80s-90s in the summer. Eventually I will install something for HVAC, but nothing high tech. I have an 8K BTU window AC that I will install in one of the high windows if I plan on working in there in the summer and it gets too hot. I may even install a gable fan below the ceiling, in the open area, to evacuate the air and **** out the hot air. I'll wait and see if I need that. For heat, I'll just go with an electric heater if I'll be working in there in the winter, or if we have a real cold spell and I want to at least keep the temps above freezing/dew point. Again, I'm just a hobbyist but who knows what I will start doing once I have a proper shop. Maybe I will put a hair dryer on the Vette over a winter?

So what exactly should I put in the building specs for the insulation and ceiling? The building will have a full length ridge vent. I'm forgetting the term used, but there should be soffit vents too, something to prevent the insulation from blocking the vent and allow air to circulate from the soffit up to the ridge vent. What's that called? I've seen them installed in builds here, but now that I'm looking for one of those posts I can't find it. Soffit vent blocker stopper... Then for the attic insulation, what type? Faced, un-faced? R##?And what about a vapor barrier below the insulation, above the OSB?

All help appreciated.

 

[DynoDave]

I have 26' 4/12 - 2/12 scissor trusses. Haven't insulated, but hope to in the next year or two. I'll be watching this.

 

[mrramsey]

I am still in the planning stages for my 24x32x12 garage. Just a hobbyist garage to store my toys and work on them. Eventually will have a 2 post, and much later will store a motorhome. I am looking to have scissor trusses to maximize interior height, as exterior height is frowned upon (need a variance as it is). 4/12 pitch roof on the outside, 2/12 pitch on the inside. I’m looking at builders to do the basics, but then I’ll do some of the finish work. So builder will do foundation, structure, doors/windows, electrical panel, and ceiling/ceiling insulation. Later on I will run electrical in the walls, insulate the walls, and sheath the walls. I am planning on OSB for the entire interior, all screwed in. This allows me to drop sheets if I need to get in the walls for anything. I’d probably paint it all too for light reflection, but I’m not looking for it to look like the inside of a house, it’s a garage after all. I figure I’d run all the electrical in the walls, and mount a series of high mounted outlets off a switch for lighting, maybe 1 or 2 banks. And then I can just hang lights from the ceiling OSB and run the cords to the high outlets on the walls. Not high tech but gets the job done.

Since I'll want the basic work structure to go up as quickly as possible and get ready for me to get working in there, I'll have the builder insulate and put up the ceiling. Working by myself that would just take forever and I'd have to buy or rent some lifts and other stuff to do it all by myself. Doing wall work and hanging lights and fans and whatnot by myself is much more reasonable.

I am in northern NJ, so think 20s-30s in the winter and 80s-90s in the summer. Eventually I will install something for HVAC, but nothing high tech. I have an 8K BTU window AC that I will install in one of the high windows if I plan on working in there in the summer and it gets too hot. I may even install a gable fan below the ceiling, in the open area, to evacuate the air and **** out the hot air. I'll wait and see if I need that. For heat, I'll just go with an electric heater if I'll be working in there in the winter, or if we have a real cold spell and I want to at least keep the temps above freezing/dew point. Again, I'm just a hobbyist but who knows what I will start doing once I have a proper shop. Maybe I will put a hair dryer on the Vette over a winter?

So what exactly should I put in the building specs for the insulation and ceiling? The building will have a full length ridge vent. I'm forgetting the term used, but there should be soffit vents too, something to prevent the insulation from blocking the vent and allow air to circulate from the soffit up to the ridge vent. What's that called? I've seen them installed in builds here, but now that I'm looking for one of those posts I can't find it. Soffit vent blocker stopper... Then for the attic insulation, what type? Faced, un-faced? R##?And what about a vapor barrier below the insulation, above the OSB?

All help appreciated.

the problem with a 4/12 standard scissor is the lack of heel height. I would suggest what is called an energy heel which will add a bit more height to the truss where it meets the wall plates so you can better insulate. Since there is minimal working space in a 4/12 scissor I would suggest blown in cellulose @ R-38-49. Be sure to install the foam channels at the eaves for ventilation. Blown in cellulose is easy to DIY and cheap. Better fire rating than fiberglass. The second choice is a faced R-30 batt. The facing IS your vapor barrier.

 

[Randy in Maine]

Spray Foam. Closed cell.

Better yet would be to use SIPs for the whole thing. My whole shop including the ceiling is made out of these...went together in a couple of days with very little waste. Very cost effective.

http://www.murus.com/products/pur_sip

 

[madmaxnj]

So vented soffits, rafter baffles (accuvent or the like), and faced R-30. Sounds like a plan.

 

[James-W]

You can use fiberglass bats with a paper face. Staple the paper to the trusses and then put up the drywall. Spray foam would be good, more expensive but a very good way to insulate the ceiling.

 

[buildyourown]

You can decide if the money is worth it but doing ceiling drywall work is actually easier than it sounds. The jack is cheap to rent and the sheets go up easy with one person. Rent or borrow some stilts and the mud goes pretty fast too. Stilts take about 3min to learn how to use.
Personally, I'd use spray foam if I was paying for it or glass bats if I was being cheap and doing it myself. Foam is so much better in every way unless you need to get in there later.

 

[James-W]

Doing drywall on a ceiling is easy if you are doing a normal 8 foot ceiling. Vaulted ceilings can be double or triple that height and in that case it isn’t so easy to do.

 

[yeldogt]

You will most likely need a modified truss at the wall to meet the energy code -- both my projects needed the separate energy review .... and one was only a simple 1 story bump out addition (w/ scissor truss). With all that often needed in NJ, I would recommend you ask the code official what's going to be required ... you may find that a retired architect working in your area can give you both the advise you are needed and drawing required for a reasonable price.

Spray foam will solve all your problems w/ the least amount of height -- but conventional insulation can be done --- both unvented under the roof or vented on the ceiling. I like unvented ... but, thats me.

You will not be able to cool that space with 8k using conventional -- spray foam with continuous operation ...... maybe.

I would not dismiss the use of SIP's They are perfect for a simple structure ... part of my current studio is made with them. energy efficient -- quiet .. quick build. Mine has a cabinet heater and surface wiring.

 

[stm317]

You're probably in climate zone 5: https://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table

So the recommended goal for attic insulation would be R50 or better. Since the building isn't built yet, something like SIPS might be a good option. If you're doing spray foam, you can probably skip all of the vents and baffles since the whole idea is to completely seal it up. Spray foam will be costly though (easily $1 or more per board foot) so to get close to the suggested R Value, you'd have a ton of money ******* in foam. After 3 or 4 inches of thickness, it's not really cost effective.
The traditional building route with vents/baffles will leave you short on room at the narrow end of the trusses. This may or may not be ok with you. The suggestions above are for living space, so if it's "just a garage" to you, having it insulated to the gills may not be critical. You could blow cellulose in there to get the R value that is suggested across most of the ceiling, but it wouldn't be possible to get it deep enough near the eaves, and you'd have to use baffles to keep the soffit vents properly cleared. But it would be cost effective.

 

[madmaxnj]

Guys,
Thanks for the replies.

With the 12' walls and vaulted ceiling, the only thing I want to be doing up there is hanging light fixtures from the OSB. That's why I am looking for exactly how to spec it out for the builder to quote. I'll DIY the electrical, wall insulation, wall sheathing later. For now, just looking to get all the specs for what the builder will do.

Since this is a garage, again mostly for storage. I am not a pro wrench and I will never be in their working daily. Should I take on a big project on one of my rides it will be weekend work. So if I need to heat or cool it, it would just be to maintain temp for a couple of days. Other than that I probably just want to keep it above freezing. So I'm not looking to insulate it at the same level as one would a house. Heck, my house doesn't even have anything close to R50 (yeah, I should work on that too, old owner left the attic a mess, I don't like going up there lol). So the blown insulation is a bit overkill for what I need. This garage is quite the luxury item, money wise, so looking to save wherever I can. As it is I'm still contemplating pole building vs Amish semi-pre-fab stick built. But I tell you, the price on the pre-fab is so close to the pole building, why wouldn't I go with stick? Anyway, just trying to say I'm not looking to put a ton of $ in insulation in a building I won't be working in daily.

Thanks
Max

 

[stm317]

I'd have a discussion with any prospective builders that you're considering and see what they advise. The blown in cellulose is often the most budget friendly way to achieve a specific R Value.

As a bit of an aside, I'd also strongly suggest putting a moisture barrier like Tyvek on the building. It will allow yyour insulation to work as intended. It's something that a lot of people with pole buildings don't think about and later regret. It's a lot more difficult to add it later than it is to put it on during the build.

Also, it may be worth considering metal liner panels on the ceiling. They're a bit more expensive than OSB per sq ft, but they come pre painted, so any costs associated with painting the OSB could very well negate the lower initial purchase price (For my building, I'm coming up with the liner panel being $.03/sq ft more expensive than .5 inch thick OSB before any paint costs). The bright white will reflect a lot of light and make it easier to see, and it usually goes up faster than OSB would. Talk this over with your builder.

 

[yeldogt]

Guys,
Thanks for the replies.

With the 12' walls and vaulted ceiling, the only thing I want to be doing up there is hanging light fixtures from the OSB. That's why I am looking for exactly how to spec it out for the builder to quote. I'll DIY the electrical, wall insulation, wall sheathing later. For now, just looking to get all the specs for what the builder will do.

Since this is a garage, again mostly for storage. I am not a pro wrench and I will never be in their working daily. Should I take on a big project on one of my rides it will be weekend work. So if I need to heat or cool it, it would just be to maintain temp for a couple of days. Other than that I probably just want to keep it above freezing. So I'm not looking to insulate it at the same level as one would a house. Heck, my house doesn't even have anything close to R50 (yeah, I should work on that too, old owner left the attic a mess, I don't like going up there lol). So the blown insulation is a bit overkill for what I need. This garage is quite the luxury item, money wise, so looking to save wherever I can. As it is I'm still contemplating pole building vs Amish semi-pre-fab stick built. But I tell you, the price on the pre-fab is so close to the pole building, why wouldn't I go with stick? Anyway, just trying to say I'm not looking to put a ton of $ in insulation in a building I won't be working in daily.

Thanks
Max

You need to find out what you can build .. I could not build with 12' walls.

 

[madmaxnj]

You need to find out what you can build .. I could not build with 12' walls.

I've already had a 'workshop' meeting with the planning board and they seemed pretty receptive. Once the main guy realized I wasn't going to become a full time mechanic running a business, he got it and said "you're just looking for a nice place to park your toys " The plan for the motorhome is the clincher on the height. I'm actually submitting the paperwork for the variance tomorrow morning.

 

[bobbyjean]

variance---da da dome..bring your checkbook-that's where the fun begins....at least in my area -add a few grand to the bottom line

 

[madmaxnj]

$350 for the application. $10 for the list of names of neighbors I need to contact. $500 in escrow for overages, so I could get some or all of this back depending on how it goes. The lady apologized to me yesterday, "sorry you have to go through this just for the height, this shouldn't be a problem." Hearing will likely be in Jan or Feb. I just want everything lined up so I can build in the spring.

variance---da da dome..bring your checkbook-that's where the fun begins....at least in my area -add a few grand to the bottom line

 

[laser3kw]

You can use fiberglass bats with a paper face. Staple the paper to the trusses and then put up the drywall

I have 30 x 40 x 12 with scissor over 16 ft and attic over 24 ft. I went with OSB on the walls and ceiling rated dry wall on the ceiling. All ceiling area is insulted as mentioned with a standoff type thing between the sheathing and insulation for air flow.

 

[finn]

Better check if the type of RV you are considering will fit in a building with only 12’ wall height.

My fifth wheel needs a 14’ door.

 

[Oldbear]

I have a 32x28 with the scissor trusses on the shorter side. I used R40 insulation batts to go with my R34 ICF walls. I did that myself and hired a local contractor/drinking buddy to let me help him with the vapour barrier (I can't swing a tack hammer straight to save my life). The more insulation you have now the less it costs later.

 

[jives]

Couple of other things to consider. . .
What is the truss spacing? 16" or 24" will make it easy for fiberglass batts, but if they are 4' spacing then you need to change you plans.

What is the load ratings on the bottom of the truss? Can you screw up drywall or OSB?

Seems like you are planning on insulating the bottom chord. What about leaving the truss web open and insulating above the top chord (e.g., insulate the roof or use SIPs), or insulating just under the roof deck?

 

[Oldbear]

Couple of other things to consider. . .
What is the truss spacing? 16" or 24" will make it easy for fiberglass batts, but if they are 4' spacing then you need to change you plans.

What is the load ratings on the bottom of the truss? Can you screw up drywall or OSB?

Seems like you are planning on insulating the bottom chord. What about leaving the truss web open and insulating above the top chord (e.g., insulate the roof or use SIPs), or insulating just under the roof deck?

Depending on local building codes you might not be able to insulate the top portion of a truss. Here in Alberta we need (or the inspectors wants to see) some air flow between the roofing layer and the insulation to prevent moisture build up and then mold. We need to have vapour barrier on the conditioned side of the insulation. I can't imagine trying to seal around all the beams in the trusses.

You could spray foam - but it would be on the underside of the roof - you'd have to respray if you replaced anything. You can do blown-in, but need to find a contractor that will do the small space.

If done it would look awesome though. You could stain and finish the exposed wood to look like old barn beams... excuse me while I go rethink my current shop design.

 

[BIG-BRO]

You mentioned doing the wall electrical yourself later, but bear in mind that you may need to run wires up over the ceiling to get to "other" wall, etc. Might be hard to spec having builder only do ceiling wiring and finish a ceiling without doing most of your other wiring.

 

[madmaxnj]

Better check if the type of RV you are considering will fit in a building with only 12’ wall height.

My fifth wheel needs a 14’ door.

It would just be a smaller class C motorhome. A lot of them are over 11', but also a bunch in the 10-10'5" range. Even new Winnebago Aspect is 10'4". Trailers and toy haulers are bigger; which I was originally thinking. But its easier to have a class C and just pull a small bike trailer, than have a 30-34' RV. Thanks for the info though.

 

[madmaxnj]

Couple of other things to consider. . .
What is the truss spacing? 16" or 24" will make it easy for fiberglass batts, but if they are 4' spacing then you need to change you plans.

What is the load ratings on the bottom of the truss? Can you screw up drywall or OSB?

Seems like you are planning on insulating the bottom chord. What about leaving the truss web open and insulating above the top chord (e.g., insulate the roof or use SIPs), or insulating just under the roof deck?

24" OC. I haven't contacted the builder yet to ask about the insulation and OSB on the walls. As others have stated, I'd rather have the airflow soffit to ridge vent, than insulate the top cord. I hear its also better for shingle temp and their lifespan as well.

 

[madmaxnj]

If done it would look awesome though. You could stain and finish the exposed wood to look like old barn beams... excuse me while I go rethink my current shop design.

I was going to paint it gloss white for light reflection. Stained might look pretty cool though. I saw a thread up here of a guy that did his is #1 or #2 plywood (no defects on the surface), looked pretty cool.

 

[madmaxnj]

You mentioned doing the wall electrical yourself later, but bear in mind that you may need to run wires up over the ceiling to get to "other" wall, etc. Might be hard to spec having builder only do ceiling wiring and finish a ceiling without doing most of your other wiring.

The wiring routing has had me thinking... I am spec'ing 1' overhangs on all sides. The panel will be in the front corner. I should be able to route through the gable end overhang to get over to the other side. Yeah, that should work.

 

[stm317]

I was going to paint it gloss white for light reflection. Stained might look pretty cool though. I saw a thread up here of a guy that did his is #1 or #2 plywood (no defects on the surface), looked pretty cool.

I know I already mentioned it, but if you're doing a ceiling, it's probably worth looking into metal liner panel. It comes pre painted, reflects a bunch of light, and will probably be cheaper than plywood or OSB by the time you paint/stain it. Should save some time compared to hanging/painting another material too.

 

[madmaxnj]

I know I already mentioned it, but if you're doing a ceiling, it's probably worth looking into metal liner panel. It comes pre painted, reflects a bunch of light, and will probably be cheaper than plywood or OSB by the time you paint/stain it. Should save some time compared to hanging/painting another material too.

Part of the reason I'm planning on OSB instead of sheetrock on the ceiling is so I can hang lightweight LED lights and I don't have to get the mounting screws in the ceiling joists. So the lights can go where ever I want. Depending on what I finally get they can go flush or hange. OSB should be fine holding up some lights.

Now you do have me thinking about the interior walls however. With the 12' walls I could do a row of OSB horizontal, so I if I want to have high shelving, spotlights, fans, old signs, neons, etc, I can mount to the studs/OSB. But I can also do something else on the lower 8' vertically. On the lower side of things, I'd probably have most things on wheels so they can be moved around, or put on dollies to move around. Really try to limit or have nothing mounted to the wall on the low side. Steel panels may work there. Do you have a link on what you used in your garage?

Hmm, I would outlets mounted low though. Not sure how that works. And windows, and doors, and a circuit panel. So I'd need tin snips, or nibblers, and then something to trim the cut edge. On walls may not be a good idea. OSB or plywood is just so easy to work with. Even though you need a saw, drill, cutter, I find that easier than dealing with drywall even.

 

[stm317]

There are countless threads around GJ that discuss the various benefits and drawbacks of different wall/ceiling materials, so I won't go into tons of depth here about them. I mentioned the metal option because you said once before that this project doesn't have an unlimited budget, and metal liner panel can be cheaper than hanging and painting OSB. If you're more comfortable with OSB, there's nothing wrong with that but you should educate yourself on all of the options so that you can make a better choice for what will work best for your budget and goals. Nothing worse than finishing a project and regretting a material choice later on. Learn about all of the options, and make a choice that you're most comfortable with.

Personally, I have a vaulted ceiling. I'm still finishing the inside of the building, but my plan is to have gloss white liner panel on the ceiling because it has many of the same benefits of OSB (Impact resistant, easily replaced if damaged, can anchor lightweight items pretty much anywhere on the panel) but it usually works out to be cheaper and goes up faster (the "goes up faster" part might really impact your price if somebody else will be doing the work for you). It will reflect a bit more light than painted OSB, and be easier for me to clean if necessary. I want my ceiling to be maintenance free. I also like the look, but that's personal preference.

I don't care for liner panel on walls. The ribs make it difficult to have shelves or things flush up against the wall, and walls are far more likely to be impacted than a ceiling. Impacts with drywall cause holes. Impacts with metal cause dents. Impacts with OSB usually don't do much at all, so my walls will likely be painted OSB with FRP panels on the lowest 4 ft for easy maintenance/clean up.

Finding examples of vaulted cielings with liner panel isn't easy. These are the best that I could do on short notice:

 

[tinysparky]

why not just do large rolls of 2" batt insulation to act as condensation blanket and to give you some min. r value.

I have been going back and forth on my scissor trusses as well, but mine are 12' apart with my purlins only 24". I am leaning towards insulating with an r15 in the purlins and calling it good for now. just want to stop condesnation.

 

[smz]

Built a 40x60 in Minnesota. 12'sidewalls with 3/12 inside 6/12 outside scissors.
White steel on ceiling with 6 mil vapor on top then 16 inches cellulose.
Sidewalls are housewrap under outside steel then 1.5 spray foam and then r30 fiberglass inside that.
Mistakes- spray foam on outside wall collects moisture that travels through fiberglass from inside, freezes, and then thaws on warmer days. Articles online talk about this "flash and batt" problem where in northern climates the spray foam should really be on the back of inside steel, then fiberglass toward outside.
On ceiling the cellulose slides down the vapor barrier and bunches up above the overhead door, I assume from door vibration. Also next time I would put housewrap under roof steel before installing. I think this would help with condensation forming and dripping.

 

[stm317]

Built a 40x60 in Minnesota. 12'sidewalls with 3/12 inside 6/12 outside scissors.
White steel on ceiling with 6 mil vapor on top then 16 inches cellulose.
Sidewalls are housewrap under outside steel then 1.5 spray foam and then r30 fiberglass inside that.
Mistakes- spray foam on outside wall collects moisture that travels through fiberglass from inside, freezes, and then thaws on warmer days. Articles online talk about this "flash and batt" problem where in northern climates the spray foam should really be on the back of inside steel, then fiberglass toward outside.
On ceiling the cellulose slides down the vapor barrier and bunches up above the overhead door, I assume from door vibration. Also next time I would put housewrap under roof steel before installing. I think this would help with condensation forming and dripping.

Any pictures of your building? It sounds very similar to what I'll likely end up with. What evidence are you seeing of the moisture issues in your walls? Is the building conditioned at all?

 

[smz]

Reached through fiberglass and found ice and moisture on face of spray foam. Fine homebuilding magazine has an article called flash and batt which explains well.
Building is 132' by 40'. First 45 x 40 is cold storage, then 60' x 40' heated, then 30'x 40' heated which will eventually be dedicated as garage for house that attaches to end. This "garage" has 9' ceilings so trusses were made so a 18' x 30' room is above it.

 

[smz]

House is 42' x 50' with 18' ceiling in front half and a loft in back half, rooms below and a couple in loft. Loft has a door that goes into room above garage, the a door on end of that room that goes into shop so that I could bring things like pool table into house loft by lifting them up with forklift.
All heated areas have floor heat, which boiler is not connected yet. Using a house furnace for now. Had the shell put up by builders and am have done cement, walls, elect, plumbing,heating and etc myself. Been an EXPERIENCE!
Definitely would do some things different.

 

[Skiff Builder]

Max,
Have you considered a conventional stick framed roof?
Using 2x10's on 16"o.c. your looking at:
50 rafters- 2x10x16', Lowes Butler NJ price 26.06ea= $1303. Plus lvl for structural ridge.
Height from top of wall plate to underside of ridge would be about 3'9". To top of ridge about 4'9".
After the ridge is up, two good carpenters can cut and install those rafters in a good day.
More space for you and toys in the garage.


You can get r30 or r38 in there

 

[Patrobot]

We also used 4/12 scissors trusses and left our vaulted ceiling open. Because I want the highest possible ceilings to accommodate our lift and collect warm air in the summer months I'm only going to insulate between the trusses. Rigid foam is easiest but expensive. I mean this is an accessory building that is already more energy efficient than our home built in the 80's.

 

[yeldogt]

24" OC. I haven't contacted the builder yet to ask about the insulation and OSB on the walls. As others have stated, I'd rather have the airflow soffit to ridge vent, than insulate the top cord. I hear its also better for shingle temp and their lifespan as well.

You will see that the shingle manufacturers have changed on this -- I have built many houses w/o venting on purpose. The new energy audits in NJ have you remove the vents -- in our climate they waste energy and cause more problems.

My first project (almost 40 years ago) was recently expanded and they removed the batt insulation filling the bays on the full roof deck in what was the attic. It looked like the day it was installed.

The key to any project is proper product -- property installed. Never use plastic or any products that restrict drying --

The one project where I did 24" OC .. I regretted. For the small cost upgrade -- I would stick with 16OC and a proper roof deck.