Venting a Four Season Attic and a Bad Air Switch
This weekend I finally got around to a project that I had been putting off for some time.
That’s because there’s no work we really need to do on the new building. The sand base has yet to be prepared by our concrete contractor in preparation for the vapor barrier, foam, and radiant heat tubing prior to the concrete floor being poured.
And right now there’s no point in spending any more time and or money on the new building when the real work we need to do before winter is predicated on having the concrete floor installed.
In the meantime I figured I might as well work on some other projects I’d been doing my best to avoid.
A little less than four years ago we paid someone to add a four season porch to the house. They framed, sided and shingled the addition. That left all the interior work, including electrical, insulation and drywalling to me.
I completed most of the other work that first winter after the four season was added except for some of the drywall (leaving the ceiling and the wall adjoining the house without).
But from that there the project languished for a couple of reasons. One reason is because of the problem I am about to describe.
The four season ceiling was vaulted, and the interior wall that separated the room from the roof space where the new roof joined the existing roof created a little “attic” space. This little space had no airflow at all, and on sunny days it turned into a oven, a fact I noticed soon after the addition was built.
On sunny days we noticed a “hot roof smell” coming from that area, and the four season area itself also got quite warm on sunny days, even in the winter.
Initially I had tried to seal the wall there to separate this space from the rest of the room. I installed fiberglass insulation and a poly vapor barrier over the wall.
However I noticed in short order that this didn’t do the job, and noticed the hot roof/tar-paper smell on sunny days. I tried to rectify this problem by gluing/sealing the vapor barrier at the bottom edge, which helped a bit but didn’t make the problem go away.
It was then that I realized that I was going to have to do something completely different to solve the heat and odor problem.
I pondered the problem for quite a while, in part because I really didn’t want to tear up the insulation that I’d already installed and start all over and because I had plenty of other projects to do as well.
Intuitively I also knew that if I just sealed the space better I would have another problem, as it would create a totally sealed little box that would heat up on sunny days with the heat having no where to escape. Attics are normally vented to deal with that issue, allowing air to come in through the soffits and letting hot air escape out ridge or roof vents.
So I had to figure out some way to vent the space.
Years literally went by as I researched and otherwise ignored the problem. After thinking about it again this year I finally got around to a fix.
Knowing that the space would be unbearably hot I had waited for some cooler days to start the project. Even with the temps only in the 80′s this week, I knew the attic space would rise to over 100 degrees during the day and I would have to be working in it.
When we bought the house it had a ridge vent, but after our roof shingles were replaced after the hailstorm in 2006 they replaced the ridge vent with regular square roof vents.
However, when they added the four season, the contractor used a ridge vent on it. (The ridge vent is the dark section at the ridge line of the roof.)
From an examination of the roof outside it was clear that the ridge vent they had installed on the four season ran past the wall that divided the room from the roof section in question.
I thus reasoned that if I could get simply get some airflow into that space that the hot air would move out through the ridge vent.
So I removed the existing vapor barrier and insulation on the wall so that I would have access to the little “attic” space.
Initially I was just going to cut some holes in the roof in that space, exposing the new space to the rest of the attic space in the house. Because the four season was an addition, the roof in that area was shingled.
After marking out where I would cut, I realized that I would later have to crawl around in the area for the next step, so I decided to remove the shingles in that area before cutting the holes so I wouldn’t later be crawling around on the abrasive shingles.
Even though the temperatures outside were only in the 80′s, it was a hot, sweaty and uncomfortable experience working in the attic space there.
Having removed the shingles, I cut two holes into the roof sheathing between the rafters, opening the space to the rest of the house’s attic. The instant I opened the first hole the space felt cooler.
Since the main part of the house’s attic was already vented, with fresh air coming in through soffit vents, it would serve as an air source for the addition roof space that when heated would vent out the ridge vent.
Only the ridge vent in that area was mostly blocked by a section of the rafter ridge beam (itself a short section just running from the existing roof to the main ridge beam of the porch) so I cut it out after first supporting the part that was left with a vertical brace.
The main ridge beam (a microlam beam) of the four season porch rests on studs on the section of wall I was insulating, the end of which is visible on the left side of the following photo.
After that was done, I went about properly sealing off the space. This time I used some two inch thick extruded polystyrene foam that we had left over from the building project.
The pieces were cut at angles to match the pitch of the roof, and had to be in small enough sections to fit between the spaces in the wall studs as they were to be nailed against the backs of the wall studs.
I tried to make sure they fit snugly and then nailed the foam to the backs of the studs with nails and washers. I got most of the opening covered with foam sheets before evening, leaving a single gap between studs open so that I could still climb into the space.
My plan was to then use expanding foam to seal the edges and any other gaps in the foam from the back (inside of the attic space), but the two cans of foam I had were over a year old and the valves were stuck and I broke them trying to get them to dispense foam.
Since it was too late to get out to the hardware store that night the project went on hold until I could get out and buy some expanding foam.
The next day I had to run to the dog grooming shop to repair the home-made dog bathing pump I installed this last winter. Kim told me that the pump would no longer turn on and off with the air switch/assembly.
I suspected a problem with the ground fault interrupter, and after checking out the assembly found that the problem was that the rubber “bulb” (the manufacturer calls it the “foot pedal”) wasn’t “puffing” out any air when pressed, and thus not activating the air switch it was connected to via a section of tubing.
I had received a new rubber bulb with the air switch when I bought it but opted to use the existing one that controlled the old pump that was already mounted on the wall. At the time I thought nothing could go wrong with a rubber bulb and tube.
Thus I neglected to bring the new bulb with me, not having suspected that part at all as being causal to the pump not working.
However, I discovered that the problem was in fact that the bulb was no longer blowing out any air when squeezed.
I inspected both the bulb and the tubing for damage, and finding none had to put on my thinking cap.
Since the sealed bulb connects to a tube that connects to the air switch, I deduced that there must be a valve on the bulb to return new air to the bulb after it was squeezed. There’s a metal bulging part on the top of the bulb that the tube connects to that was obviously that valve.
Figuring the air intake on the valve might be clogged I tried soaking it in hot water to clean it off without success. Eventually in the process of messing around with it I accidentally broke the valve apart. When I did so it was obvious that it was badly corroded.
So I pulled the remains of the broken valve out of the bulb, and found after removing it that simply sticking the tube into opening of the bulb worked as a temporary fix since enough air leaked around the junction of the tube and bulb to allow new air to be drawn into the bulb, yet sealed tightly enough that air was blown through the tubing when the bulb was squeezed.
I’ll have to head back to switch the bulb out with the new one soon though.
(Edit 9-2-2010: I found that the new switch bulb doesn’t have a valve at all. After holding a finger over the hose connection on the new bulb and squeezing it I found the bulb does not refill with air. It’s obviously just a nipple for the hose connection. There must be enough air leaking at the air switch connection itself to return air to the bulb.)
When I got back home it was back to my insulation project.
I finished cutting the last pieces of rigid foam to fit the attic space. I had to wait to put in the last pieces that would completely seal the space until I’d foamed the cracks on the foam that were already installed from the back.
Once I’d sprayed in the expanding foam I affixed the last pieces in the opening I’d left for access using construction adhesive and strings run through the foam tied to nails on the fronts of the studs which acted as temporary clamps until the glue set.
The next day after the foam had cured I replaced all the fiberglass insulation in between the wall studs.
When I pulled out the insulation at the start of this latest attempt at this project I had noticed that some mice had been tunneling through the attic insulation, so I decided to add strips of wall sheathing to the gaps below the roof sheathing and between the rafters that were created when they cut away the roof overhang to at least try and keep the mice in the attic.
Then I foamed all the gaps that hadn’t yet been covered.
Once that foam cures I need to trim off any that has expanded out beyond the plane of the studs since it will be drywalled. Then I need to replace the vapor barrier.
Of course after I completed all this work I remembered why I put this project off until now…
Now I’ll monitor the area for a while to ensure the problem has indeed been fixed too.
Filed under: Building Construction 2009-10, Dog Grooming Business, Home, Home Projects on August 29th, 2010 | No Comments »
