Ventilation helps to keep air moving in the shed. Warm air is capable of holding more moisture. When it rises, the moisture can condense on anything it touches, eventually the underside of your shed ceiling or roof sheathing.
It also condenses on anything that is colder than the air, so metal objects are common places for this to occur. Condensation usually takes place when the air is still. When the air is moving, moisture is unlikely to condense. Proper ventilation will keep the warmer, moisture-laden air moving and help it escape the shed.
The best place to install a vent is in the roof, since a roof vent is situated at the highest point in your shed, it will help this air to get out of the shed, carrying its moisture load with it.
Sufficient ventilation for the size shed you have goes a long way towards keeping excessive moisture out of your shed. Moisture can cause all sorts of problems, including mildew, mold, and eventual rot. Not only can your stored items become damaged by mold and mildew, but your yard machines will be more subject to rust.
Lawnmowers, tillers, string trimmers and ATVs can all be damaged by rust. In addition, battery-operated yard tools are becoming more popular. There are now battery-powered string trimmers, leaf blowers and lawnmowers. Even chain saws and snow blowers come in battery-powered models.
While batteries for these items are normally stored inside the house, the electronics in these items can be damaged by excess dampness in your shed. Of course, power tools, such as drills, power screwdrivers and staple guns, have long come in battery-powered forms, and these can be damaged as well.
What is the Best Way to Vent a Roof?
There are many types of roof venting available. Below are some of the most utilized, along with their pros and cons:
Ridge vents – These are usually installed when the roof is installed. They run along the ridgeline of the roof, formed as a sort of raised cover over the roofline, allowing air to escape.
- Pros: These vents are practically invisible to anyone looking at your roof. Some involve placing asphalt shingle roof caps on top of them after installation, making them blend in completely with the roof. They balance air temperature by allowing warmer air to escape the shed. When temperatures are cooler, the vent design allows the cold air’s pressure to keep the warmer inside air from escaping. The design leaves no access for rodents or other pests.
- Cons: While they can work without other vents, you really need to have sufficient intake vents to take advantage of this venting design. There is also a chance that rain could get in if rain blows in the right direction. Ridge vents can be more costly than other types of venting and don’t work as well in warmer climates.
Turbine vent – These vents consist of a wide, vertical pipe shape with a turbine on top, much like a mushroom shape. It turns with a breeze catching the turbine fins, causing it to spin. This turbine action creates suction which enables the turbine to draw more air out.
- Pros: This type of vent is relatively inexpensive and easy to install. They can be installed in as little as a half-hour or less. They don’t require any type of power. It can even be installed on metal roofing. Larger sheds simply need more than one.
- Cons: These vents do require at least a little breeze to work well. If you live in a southern climate, you may have many hot, humid days when the air is still. This means that on the days you want to vent to work the most, it may not work at all. While these vents come in various colors to match your roofing, especially with metal roofs, some people simply don’t like the looks of them.
Vented skylight – These vents provide a skylight as well as venting. Warm air rises then flows out. They can be opened whenever the sun is out or anytime no precipitation is expected.
- Pros: These skylights provide additional lighting in your shed without installing electricity, and the skylights themselves don’t need power.
- Cons: Unless you get an automatic skylight, you’ll have to go up to it and manually open and close it. Automatic skylights not only require power but are pretty costly themselves. Installation must be done carefully to prevent leaks. If anything gets in the way of closing the vent completely, such as a twig piece or acorn cap in the track, you’ll have rain coming in.
Roof vents – Roof vents or box vents are static vents placed near the roof ridge. They look like small boxes. They are covered to keep out rain and usually vent the warm air out of the sides or out from underneath a raised cap.
- Pros: These often come in colors to more closely match your roofing color. They can be installed on the side of the shed away from the street and so be out of sight. They don’t require power or much maintenance and are designed so that rodents can’t get in.
- Cons: While these vents do work with the natural convection in your shed, they work better with a breeze, which you may not have on those hot, humid days.
Cupola – Cupola vents are simply a cupola with venting installed in the sides rather than a window or some sort of decoration.
- Pros: These vents are very decorative, and don’t look like something utilitarian.
- Cons: These vents are not very effective by themselves and work best with intake vents. They are much more expensive than some other types of roof venting and sometimes not as functional.
If you need more ventilation, especially for air intake, you might consider drip edge vents. Most sheds don’t have soffits in their roof installation but just have overhangs. A drip edge vent is installed under the shingles or other roof covering at the edge of the overhang and provides intake venting in your shed.
How Much Shed Ventilation Should I Have?
This is an important consideration. You can actually have too much ventilation. Too much air exhaust leaves a bit of a vacuum, and some of the exhausted air can be pulled back in to compensate. Even precipitation can be pulled in.
Fortunately, it’s easy to figure out how much ventilation you need. Multiply the length of your shed by the width to figure out the square footage. Many building codes specify one square foot of ventilation for every 300 square feet of space if a vapor barrier was installed when the shed was built or installed. If there was no vapor barrier, the figure doubles to one square foot of ventilation for every 150 square feet of space.
How Many Roof Vents Do I Need?
There are many types of roof vents. These include ridge vents, turbines, power vents, box vents, and cupola vents. Soffit vents are common on homes, but most sheds are not built with soffits. As far as how many are needed for your shed, all your venting should follow the formula for ventilation.
Some venting can be designed for intake, working with the venting placed for exhaust. Your building supplier should be able to give you some advice on what would work best for your size shed, your climate, and the shed’s placement. How much sun and shade may have an impact on the types of ventilation that are best suited for you.
Where is the Best Location for a Roof Vent?
Ridge vents are generally located all along the top ridge of the roof. For other types of roof venting, a common placement is in the center of the roof either on the ridge or as near to the top as possible. This will allow it to work in combination with vents in the sides of gable roofs or other vent placement. The roof vent will draw air up and out, while the side vents will draw fresh air in.
What Type of Roof Vent for a Metal Roof?
Ridge vents are the most popular venting for a metal roof. They are installed when the roof is installed and provide ventilation all along the ridgeline. Gable vents are often installed to work with ridge vents. Turbine vents are also used on metal roofs, with some colored to match the roofing.
Are Powered Roof Vents Worth the Cost?
Powered roof vents or attic fans work with a thermostat. When the heat builds up past the setpoint, a fan turns on, venting the warm air outside. While some people have these installed on their home roof to keep the attic from being too hot, they have downsides there, as they can fight with air conditioning.
For a shed, you need to have electricity run to your shed. You also may not be able to tell if the fan has stopped working unless you find that it just won’t go on even when you adjust the thermostat.
Solar-powered models are available, but you can have really hot days that are too cloudy to allow the fan to work, rendering them less than useful. Also, many models tested really don’t move that much air.
Actually, powered roof vents were designed to keep attics from getting too hot, not for cooling a shed. There really isn’t enough advantage in using one for your shed to justify the cost, even if you already have power run to your shed. Non-powered solutions will do just fine for a shed.
How to Install Roof Vents
Ridge vents – Remove the nails holding the shingle ridge cap in place. There are usually two nails in each cap, one on either side. A pry bar will help loosen the nails and help you pry off the shingle cap. Once you have the shingle caps off, cut the shingles back on either side. This is usually about three inches, but the ridge vent instructions should tell you how far to cut back on either side. Remove all the underlayment as well so that the wood sheathing is visible.
You’ll need to cut back the wood decking, usually so as to have an inch of clearance on either side of the ridge board or ridge pole. If you have a roof constructed with trusses, you may not have a ridge board. These require at least an inch of clearance on either side of the ridge.
Measure down from the ridge the proper distance. Marking your cutting line with a chalk line will help. Remove all the framing nails that run through your potential opening, then nail the decking back below the cut lines. Cut your decking along the chalk lines. A circular saw will work best for this. Be careful to adjust your depth of cut so that you only cut the decking boards and not into the rafters or trusses. Install new shingles to cover any exposed decking.
There are two main types of ridge vents. There is the shingle-over style and aluminum style. For the shingle-over venting, mark two chalk lines on either side of the ridge according to the manufacturer’s guide. Place the vent along the reference lines and nail it to the decking. Your installation guide should list the required nails. Then install asphalt shingle caps over the vent, again using the recommended nails in the guide.
For the aluminum vents, mark your distance lines as before. You’ll need polyurethane caulk to apply to the underside of the vent flanges. Place the venting into position, then nail it to the roof decking and rafters or trusses. Your installation guide should list the recommended nail placement. Install any connectors and the end caps to make sure the venting is watertight.
Turbine vents – As these vents don’t go right on the ridgeline, they are usually placed on the side of the roof that is seen less often. You’ll need to decide how many you want first, according to your shed size. If installing one, it goes toward the center of your roof length. If installing two, each should be placed a quarter of the length of the entire roof from the edge on either end. They should be installed near the peak of the roof so as to be exposed to wind from every direction.
Go inside your shed up to the roof with your turbine neck to trace an opening. Drill a hole all the way through the roof in the center of the circle you just made. Then go on top of the roof, place the turbine neck on the roof with your drill hole in the center and trace around it. This outlines the hole you will cut.
Remove the shingles that fall within the circle. You may need a reciprocating saw to cut through the decking. Loosen the shingles and underlayment at the corners so the vent’s base can slide underneath.
Install your base according to instructions, usually sliding it under nearby shingle edges on the top and sides and leaving the bottom part extending over the shingles. You’ll probably need sheet metal screws or specific nails for this, and the base should have pre-drilled holes. You will also need to use caulk before installing to seal the base to prevent leaks.
The top of the vent neck turns to adjust the tilt of the top so that the turbine part will be vertical. This should have a mechanism to allow it to be locked into place. Seal all seams on the neck and around the base and nail holes. Place the turbine on the neck and fasten. Check to see that the turbine turns freely.
Roof vents – Determine where you want your vent or vents. They should be positioned between rafters or trusses, usually on the side of the roof where they will be least visible. For most sheds, you won’t need more than one or two. From inside the shed, drill a hole through the roof in the middle of the space you want for your vent. Go up to the roof, locate the hole, and mark out the hole you’ll need with the drill hole in the center.
Then cut through the shingles and the roof decking. Use a pry bar to loosen the shingle edges around the hole. Put a thick bead of caulk all along the underside of the vent flange. Slide the top and sides underneath the shingles. The bottom edge of the flange goes over the shingles.
Fasten your vent to the roof with the recommended nails or screws. If your instructions don’t tell you how far apart to space your fasteners, a few inches apart should suffice. Caulking any exposed nails or screws will add to the moisture protection.
While having a roof vent or ridge vent is a great way to let out hot air, they work best when combined with other venting for intake, such as gable vents. Air circulates with fresh air coming in the gable vents and out the roof vents. On houses, this airflow is usually accomplished with soffit vents, and most sheds don’t have soffits, just roof overhangs.
If you don’t have gables or feel you need more ventilation, drip edge vents installed on your roof overhang will provide ventilation much like soffit vents.
Proper ventilation will not only prevent moisture problems but also keep fumes from gasoline-powered machines and other sources from collecting in your shed. It’s an important part of owning and maintaining a shed.