Shed Insulation & Venting

[d1ode]

Trying to figure out best way to insulate/vent my shed. Here's my current situation... Renovating my shed and it has a new roof with a ridge vent. I am planning to insulate the inside of the roof and the walls with R13 or R19 fiberglass. The inside walls I will also put some OSB plywood on top of the insulation. Was also considering just using foam board on the inside of the roof so I have a cleaner roof for more storage space.

Question is... what sort of venting should I have? I currently have a ridge vent, but the fiberglass insulation is mostly blocking it. I can either block the vent or I can pull the fiberglass back a little so it doesn't block the vent. I can also install other vents somewhere else, but I don't have soffits or anything.

 

[drx2]

Are you planning on heating/cooling the space? If not, then I don't think the insulation would be of any benefit.

 

[d1ode]

I *might* heat or cool it in the future. But regardless, I thought insulation helps to keep the shed cooler in the summer and warmer in the winter?

 

[matt_i]

I *might* heat or cool it in the future. But regardless, I thought insulation helps to keep the shed cooler in the summer and warmer in the winter?

The insulation is a resistor in electrical analogy terms. It just slows the flow of heat transfer. But you still need some kind of heat source or driven heat transfer to really make it worthwhile imo.

 

[nadogail]

Do yo plan to add heat to your shed? Or remove heat from your shed?

IMHO, Insulation will be great to have in either case. To reduce solar heat gain you might add shade above or along side of your shed.

 

[d1ode]

Do yo plan to add heat to your shed? Or remove heat from your shed?

IMHO, Insulation will be great to have in either case. To reduce solar heat gain you might add shade above or along side of your shed.

Depends on how hot/cold it gets in there and how much I end up using the shed. I might add A/C or heat at some point in the future, but not at this time.

 

[bdbecker]

How are you planning on enclosing the ceiling - across the roof or across the rafters? Do you not have soffits at all, or just no soffit vents?

Ridge vents are meant to work with soffit vents to draw air through the attic. If you are just missing the soffit vents and are planning on enclosing the space at the rafters (creating a flat ceiling with attic space), adding vents to the soffit is not too difficult - I did it on my garage - just make sure you do the calculations to make sure you have the correct amount of net free intake vent area.

If there is no way to add soffit venting, removing the ridge vent and adding in gable venting is probably your best course of action. Gable vents aren't nearly as effective as a soffit/ridge system, but are better than nothing at all. Using gable vents with a ridge vent is not really recommended because it can cause the ridge vent to become an intake, sucking rain or snow into the attic.

If you are planning on enclosing the space at the roof (creating a vaulted ceiling with no attic space), that is a whole different can of worms.

 

[thammel]

Staple styrofoam insulation baffles to the underside of the roof sheathing first before insulating. That will allow air to flow from the eaves to the ridge vent. As said above, the insulation will flatten out the peaks and valleys of the temperature swings but the shed will still get hot in the summer and cold in the winter. If you want to do something in the shed in the winter a small heater would help a lot.

 

[Bretny]

By the looks of it you dont have much room for baffles and r12 alone. Are you running the insulation up the rafter or on the ceiling joists that are horizontal?

I find that ridge vents do a pretty poor job of venting on sunny days. Do you alreaty have gable vents like most sheds?

 

[d1ode]

How are you planning on enclosing the ceiling - across the roof or across the rafters? Do you not have soffits at all, or just no soffit vents?

I want to keep the vaulted ceiling with no attic space. The insulation is (and will be) along the rafters, on bottom of the roof.

Staple styrofoam insulation baffles to the underside of the roof sheathing first before insulating. That will allow air to flow from the eaves to the ridge vent. As said above, the insulation will flatten out the peaks and valleys of the temperature swings but the shed will still get hot in the summer and cold in the winter. If you want to do something in the shed in the winter a small heater would help a lot.

That's a good idea! But not sure how I will put in some soffit venting... See the photos below.

By the looks of it you dont have much room for baffles and r12 alone. Are you running the insulation up the rafter or on the ceiling joists that are horizontal?

I find that ridge vents do a pretty poor job of venting on sunny days. Do you alreaty have gable vents like most sheds?

Running the insulation on the rafters. Would really like to keep the "attic" space there exposed for storage purposes.
I do not currently have any gable vents.

 

[d1ode]

Attached are some additional photos. Any suggestions for how to put in soffit vents? Looks like there's a 2x4 and trim in my way.

The roofing & shingles are brand new, so I'm reluctant to rip that up and install edge vents under the shingles.

 

[yeldogt]

Foam will work but, to really seal it you will have to can foam the joints. .... batts will be easier. Just fill it up ....

What do you think you need soffit/ ridge venting for ... I wish people really understood what venting does or does not do. Tell me ... are you venting the walls. ??? What is the difference between the wall and the roof? Same construction ... does the sound side siding need to be vented?

 

[d1ode]

Foam will work but, to really seal it you will have to can foam the joints. .... batts will be easier. Just fill it up ....

What do you think you need soffit/ ridge venting for ... I wish people really understood what venting does or does not do. Tell me ... are you venting the walls. ??? What is the difference between the wall and the roof? Same construction ... does the sound side siding need to be vented?

I really I don't understand what venting does or doesn't do, which is why I'm asking the question here. Certainly I could block the ridge vent so it doesn't vent, but not sure which option would be better to do. I'm not currently venting the walls... only vent I currently have is the ridge vent.

 

[yeldogt]

Most people are coming around and not venting ... although unvented structures have been around for as long as vented.

There is plenty of information available on why not to use in attics and crawl spaces.

 

[d1ode]

Most people are coming around and not venting ... although unvented structures have been around for as long as vented.

There is plenty of information available on why not to use in attics and crawl spaces.

In my limited knowledge, seems like there might be a concern for moisture accumulation if it's totally sealed...?

 

[bdbecker]

I want to keep the vaulted ceiling with no attic space. The insulation is (and will be) along the rafters, on bottom of the roof...

Without rebuilding the rafters/roof to add soffit vents, and considering that you want vaulted ceilings, you might as well just get rid of the ridge vent and pack the cavities full of loose cellulose or spray foam insulation and have no venting at all. There's a lot of debate about the best way of doing this, so just be aware of what you're getting into.

https://inspectapedia.com/insulation/Insulate_Cathedral_Ceilings.php
http://www.applegateinsulation.com/Product-Info/Technical-Pages/249234.aspx
https://www.doityourself.com/stry/cathedral-ceiling-insulation-4-mistakes-to-avoid

 

[itb45]

for those saying no insulation is needed unless you have ac or heat, that is total BS. I just redid my detached garage, and when I was halfway done, I measured the temperature of the ceiling joists on the bottom, there was a huge temperature difference between the ones that had insulation and the ones that didn't.

My main garage has no insulation, right now if you walk in it anytime after mid day, you can barely breathe its so hot. The detached garage that has R13 in the walls and R30 in the roof, stays more comfortable than the house. Both garages face the exact same direction.

I would vent, there is a noticeable difference. Especially once the sun starts to go down, the attic cools much faster. Light wind pushes air up the soffits and hot air out the vents, without soffit vents you don't have a fully open system that can exhaust the hot air.

I just redid my detached garage, it had two spinning vents on the roof but no inlet vents.
I drilled two 2.5 inch holes between every rafter for sofit vents, then put 4ft baffles, and R30 insulation along the joists. Put the thickest insulation you can on the roof portion, makes a huge difference.

When I was installing the baffles, I could feel air coming in through the sofit vents.

 

[bdbecker]

for those saying no insulation is needed unless you have ac or heat, that is total BS. I just redid my detached garage, and when I was halfway done, I measured the temperature of the ceiling joists on the bottom, there was a huge temperature difference between the ones that had insulation and the ones that didn't.

My main garage has no insulation, right now if you walk in it anytime after mid day, you can barely breathe its so hot. The detached garage that has R13 in the walls and R30 in the roof, stays more comfortable than the house. Both garages face the exact same direction.

I would vent, there is a noticeable difference. Especially once the sun starts to go down, the attic cools much faster. Light wind pushes air up the soffits and hot air out the vents, without soffit vents you don't have a fully open system that can exhaust the hot air.

I just redid my detached garage, it had two spinning vents on the roof but no inlet vents.
I drilled two 2.5 inch holes between every rafter for sofit vents, then put 4ft baffles, and R30 insulation along the joists. Put the thickest insulation you can on the roof portion, makes a huge difference.

When I was installing the baffles, I could feel air coming in through the sofit vents.

Totally agree. This is my first summer with an insulated ceiling and I can definitely tell a difference. I also got a dehumidifier which also makes a huge difference. When I go out to my garage on a humid 95 degree afternoon, low-mid 80's and dry air is actually pretty comfortable.

 

[d1ode]

for those saying no insulation is needed unless you have ac or heat, that is total BS. I just redid my detached garage, and when I was halfway done, I measured the temperature of the ceiling joists on the bottom, there was a huge temperature difference between the ones that had insulation and the ones that didn't.

My main garage has no insulation, right now if you walk in it anytime after mid day, you can barely breathe its so hot. The detached garage that has R13 in the walls and R30 in the roof, stays more comfortable than the house. Both garages face the exact same direction.

I would vent, there is a noticeable difference. Especially once the sun starts to go down, the attic cools much faster. Light wind pushes air up the soffits and hot air out the vents, without soffit vents you don't have a fully open system that can exhaust the hot air.

I just redid my detached garage, it had two spinning vents on the roof but no inlet vents.
I drilled two 2.5 inch holes between every rafter for sofit vents, then put 4ft baffles, and R30 insulation along the joists. Put the thickest insulation you can on the roof portion, makes a huge difference.

When I was installing the baffles, I could feel air coming in through the sofit vents.

Ah, okay! Sounds like I should go ahead and install baffle vents with a 2" hole in the "soffit" for a small 2" round soffit vent in each channel. Then put as much insulation on the baffle vents as I can. What do you guys think?

Rafter Vent
Top Plate Wind Block Seal
2 Inch Round Soffit Vent

 

[itb45]

I did 2 vents per channel.

I worked out the sq in of the roof vents, and then made sure I had the equivalent or more in sofit vents.

To cover the holes, I drilled a 2.5" hole, then took mesh screen cut into squares, placed it over the hole from the inside and pushed 2" black ABS pipe into it. Then put one screw threw the ABS to secure it so it doesn't fall out. From the outside you just see the mesh, actually came out really nice.

Was way cheaper than buying vents as I had a lot, and was going to be several hundred dollars in vents. That method cost me about $30

 

[Chuckster in NJ]

For a shed the "foil double bubble foil" should be more than adequate as an AFFORDABLE radiant barrier...... "IF" you are not conditioning the space.

BTW! Proper venting is a must to avoid moisture buildup.

 

[yeldogt]

Ventilation brings moisture .... it's not doing anything.

Having a hole in a building to bring in outside air -- it not that same as ventilating a roof.

Do some research on what those plastic baffles are doing -- and more important not doing.

Understand that fiberglass is the worst performing insulation .... it has one saving grace. It's the cheapest. Fiberglass insulation requires a VB on the heated side to protect it from human moisture created inside a house.

Venting a roof just pulls conditioned air from a building -- it also introduces humid air from outside to the very place you don't want it. GBA -- has a recent article about this.

Cathedral ceiling get packed .... if fiberglass use VB on heated side ... never a #1 like plastic. Plastic = bad. Bring the whole building in -- all conditioned.