Some home designs cause attic layouts which need ventilation help. Installing a solar powered attic vent can be a great solution.
This is the second solar powered fan vent that I have installed. The first was a gable end vent, which I am using for air changes inside the attic near the HVAC system. That fan blows air over the main duct system to help drive the hot air away (an idea that I am experimenting with). Because of the U-shaped pattern of my home, one bedroom is exposed to three exterior walls with a low attic over this space. This room was in the front of the home, so soffit vents were not installed; however, there was a ridge vent. I did install some soffit vents, but the heat still builds up over this room. I decided upon a solar powered vent, since I do not have to run wiring; I am not using more electricity from the grid; and mechanical ventilation can help when passive means did not do enough.
There was a set of instructions that came with the vent, but my situation called for a change of plans. The steps are simple. Drill a hole between the two rafters from inside the attic where you want the vent to be paced. Push a nail through this hole to find it on the roof. Here was my problem. I had already been working in the attic earlier, and I was worn out from that experience. Because of the low attic space, I would have to crawl from one arm of the U to the other end with my cordless drill. Squeezing into a space where I would have limited movibility. I changed the steps to allow me the chance to do everything from on top of the roof.
Finding where to make the hole for the vent
I have a hip roof. I know that my rafters are roughly 20″ on center. Where my ridge (the top of the roof) met the two rafters going down for the hip, I measured 50″. This would place me between two rafters, but I knew that I would not be the middle. There would be a rafter coming down from the ridge, but due to other framing, that rafter might not be placed right where I was assuming. This means that I could be several inches off from the center, so I am not assuming this is my center; this is the spot where I will work.
Remove the shingles and roofing paper
I do not have spare shingles, and I wanted to re-use the existing shingles. These are composite shingles. I used a small crowbar to lift up the nails. I did have a drywall saw to cut the shingles too. I removed the complete shingle when possible to expose an area larger than what I would need. The drywall saw came in handy to cut the roof paper. A utility knife would work, but the drywall saw would cut the shingles, and I could use the saw for cutting the hole.
Planning the hole for my solar attic vent
My home was built in the sixties. This means that originally the home had wood shingles. I mention this because I have a slightly different framing situation than newer homes. On a newer home, the sheathing is attached to the rafters. With wood shingles, there are boards attached to the rafters, and the shingles are affixed to these boards. When the roof was switched over to composite shingles, the sheathing is placed on top of these boards. When looking down at my work area, I have more nails in the sheathing, so I cannot determine where the rafters are due to the nailing. Near my 50″ mark, I found a double row of nails. The instructions called for a saber saw, but most homeowners have a circular saw. I made two cuts on the inside of this row of nails. The sheathing came to an end close to my center point. I made a third cut connecting the two previous cuts at the bottom, being careful not to make these cuts very large. The dry wall saw completed my cuts, and the crowbar pried this piece out. This hole was large enough for my hand. I could feel and see the position of the rafters. Without having the drill hole center point, creating a smaller hole serves for finding the larger hole placement. What should be mentioned is that the attic vent should be near the ridge. I do have the ridge vent, but this attic vent should pull air through the soffit vents through the entire attic space. With heat rising, the best place is near the top.
Cutting a hole for the attic vent
I could use my scroll saw, but with sheathing and boards, the thickness may be a bit too great for my scroll saw. The instructions suggest having a 15″ circular hole for the opening. I thought that my circular saw would work well, but I could not have a circular hole. I made a rough octagon. The drywall saw and crowbar were used in conjunction with the circular saw to make an opening. This opening had the sides 15″ apart, but admittedly, this was not a perfect octagon. I then cleaned up my mess. I did not want to leave wood on the insulation (pushing down on the insulation does begin to cause it to loose its effectiveness; granted not much). Sweeping sawdust away from the roof space will mean that the attic vent flashing will sit flat against the sheathing.
Attaching the attic vent
I slipped the top flashing of the solar attic vent under a row of shingles. I then lifted up the vent to use my hand to find the hole to position the hole of the vent over it. Once in place, I screwed deck screws that came with the vent through the two holes for the vent flashing, which are now under a row of shingles. This helps prevent water from penetrating the roof. I use roof nails to affix and flatten the sheathing on the bottom part of the flashing. There was a bump up on one side of the flashing, so I nailed there too. I gave the vent two coats of paint on the ground. I use a spray paint meant for car parts (high temperature automotive paint can be found in spray cans at any automotive parts store). I did my touch up paint for any scratches that happened when installing the unit after the installation.
Re-shingling the roof
I have my fairly complete shingles set to one side. I place them over the sides of the vent flashing matching up to the ends from the previous shingle sheet. Covering over the sides of the flashing does help prevent moisture damage to the roof. Here a utility knife may have been better, but folding, bending, and cutting worked well. Do not place the shingles on top of the existing shingles to cut them (you may cut into the other shingles). By reusing the older shingles, you do not have the obvious color differences in shingles on the roof, so the unit looks more like it has been there. I start from the bottom, shingling my way up the vent, following and matching the existing rows. When I came to the last row to install, I had to cut off some of the top of the shingle to slide it under the top shingle row. Nails go above the darker black line on the shingles. This is a glue line, which helps keep the shingles together. Each nail is under another shingle, so they will not rust, allowing moisture penetration. The nails at the bottom of the solar attic vent flashing need to be caulked to protect them.
Final installation step
My unit had the solar panel already attached and wired to the unit. The panel sits atop of the vent. When exposed to the sun, the vent comes on, so I left a box over the panel during the installation. I removed the box. This roof is on the front of the home on a roof field facing west. I want the solar panel facing south. On this unit, wing nuts held the solar panel into position, so I could loosen them to face the panel in a south westerly direction (this is where the panel would obtain the most sun during the heat of the day. I tighten the wing nuts down when I have my desired position. Done.
The process took about an hour. With my low sloped roof, the work space was ideal. A higher sloped roof would be better for my home, but you need to take some precautions about slipping down the roof. I did this by myself. The task was really a one person job, except for one part: moving the solar attic vent up to the roof. The unit is not too heavy, but it is large (the one that I purchased – there are smaller ones). Going up the ladder, keeping the box on the panel, while not damaging any parts was a job that would have been better with two people on two ladders. This is on a front roof, and I now have a large unit sitting on this field, visible from the street. Most people do not like them here, because they are not beautiful; however, comfort inside the home is more important to me than having a beautiful roof line. This may be a consideration if selling a house. Considering the amount of heat which greeted me when I cut the hole, I am glad to have this vent.