Venting Attic

[Oldmandan]

Hi,
I've been searching the www for an answer to my problem for awhile now, but no luck. Hopefully somebody here has the knowledge to get me in the right direction.

I have a condo, with a loft that has been added by the previous owner. I use it as an office, but it gets so hot up there, I can't go up there in the summer. It can get as hot as 108-110 in August. As a point of reference, the condo is approx. 1400sq. ft. in Anaheim,CA

I've attached a diagram below. The loft only spans half the width of the house, the other half of the house has a normal attic which connect to the small area in front of the loft. I have used my friends smoke machine to blow smoke up into the roof vents of the small attic area, and it just lingers. The whirlybird on the other side of the house is apparently not strong enough to vent this small area. My first thought is to put a attic fan in the smaller area, but everything I read says it must be placed just shy of the roofs peak?

So my questions are?
1. Is it recommended to remove the batting behind the wall?
2. What is the best location for the new attic fan?

I'm open to getting a second attic fan for the larger side of the house if it's needed.

 

[nealtw]

Is there a clear path for air to travel from the lower roof to the roof with the whirly vent?
Your picture also shows something that looks like a vent between the two roofs which should not be there. I would also be looking at the venting in the ceiling/roof over the new loft

 

[Oldmandan]

Is there a clear path for air to travel from the lower roof to the roof with the whirly vent?

Hi Neal, thanks for your quick response. Yes it's clear, but it has to make a 90 degree turn to get to it, and after my smoke test I can see that the smoke would not go that direction. It just lingered in the lower roof area until it dissipated?

Your picture also shows something that looks like a vent between the two roofs which should not be there.

Correct, there's a vent there, Should I block that off? I neglected to draw the other 2 small 1" tall vents on the roof of the larger attic area. I added them to the picture below. I've wondered if all these vents so close to the whirlybird was keeping it from working well?

I would also be looking at the venting in the ceiling/roof over the new loft

The roof above the loft has no attic, it's a vaulted ceiling all the way down to the first floor. Is there some sort of special vent than can be used for vaulted ceiling applications?

Again, thanks for your reply

 

[Oldmandan]

Here's a birdseye view

 

[nealtw]

How it should be is intake vents at the soffets and exhaust vent on one side of the ridge
When the whirlly was added the other shoud have been closed as it will just pull air from the easiest path, the gable vent in the wall should be closed. My guess is the the whirly was installed when the loft was finnished to help with venting that roof.
You could just staple cardboard over these holes from the inside and do your smoke test.
Above the loft there should be a space above the insulation for air to flow from soffet to the ridge.

 

[Oldmandan]

Neal, I will try that. Thanks for your help

 

[joecaption]

The vent you have now would vent one rafter bay and that's it.
With a shed style roof there is a way to do it with a venting system that's built in to the highest part of the roof, and is attached to the wall.
I'll see if I can find a picture of it.

 

[joecaption]

DCI Products, Inc. - SmartVent Shed Roof Application

Another way is to install a square gable vent in a side wall outside.
It would go in the area between the ceiling and roof rafters.
That would only work if it was not a catheral ceiling.

 

[nealtw]

Joe: It looks like the vaulted ceiling was part of the origanel construction and hopefully was strapped which would allow air flow to the vents. I was just going after one problem at a time to see if he can get air to move thru the shed attic. The next question is if there is soffet vents both ends of the building and somehow test the airflow espeacially like you say the vaulted roof.

 

[Oldmandan]

Correct, the vaulted roof was original. As far as I can see there is no venting at all in the vaulted ceiling area of the house.

I like the idea of the smartvent, it seams ideal for what I need. However, I don't think the association is going to allow me to do that level of construction without a contractor, if they even approve it.

I've thought about putting a fan between the 2 roofs to draw air out of the shed roof into the larger roof, controlled by a thermostat? It might just be easier to put another whirlybird or attic fan on the shed roof though?

 

[nealtw]

On the bottom of the shed roof, you are showing a vent. Do you have soffit vents across the bottom and if you do, do you also have soffit vents at the bottom of the long vaulted roof? What Joe was talking about was a vent at top of the vaulted roof above the windows. If there is 1x4 or 2x4 cross strapping on top of the rafters, the top vent may not be required. If you add another vent the shed roof, you would need to block the air flow from that area to the main attic.

 

[Oldmandan]

Neal,
Yes, there are soffit vents at the bottom of the shed roof. But none at the bottom of the vaulted roof. I can't see any venting at the top of the vaulted roof above the windows, but I will take a closer look once it stops raining.

I blocked the vents in the main attic yesterday, and will smoke test it again sometime this week.

 

[nealtw]

While you are up there have a look at the construction of the roof/ceiling over the vaulted area, If there is no venting there you might be fighting a losing battle.

 

[notmrjohn]

Do not remove the batting between loft and attic, you may want to add some with a reflective facing toward attic.
Block the wall (gable vent), are there intake vents at bottom under that roof?
Turbine may be pulling air thru the 2 small vents. You want air to enter low and exit high. As neal sed any exit vent will "pull air from the easiest path," use something more rain, heat resistant than cardboard. Painted plywood, foil clad insulation panel. Secure it cause vents will try to suck it off.
You could duct from lower attic thru gable vent area, but it would have to be engineered so as not to make that easiest path, leaving large area unvented.
A long weather shielded "ridge vent" at top of lower roof, with intakes (soffet vents) low would be better than turbine or powered vent, but hot air would rise against loft wall, possibly damaging siding. (Should have looked at smart vent link earlier)
But all that removes heat from that attic, not loft. Is venting space in cathedral not connected to rest of attic? And there's that misplaced vent there too. Need soffet vents below. Smartvent again?
Or joe's wall vents. ( hello, joe, whadda ya know? fancy meeting you here. I got here by US mail, poor mike These folks will soon be sorry.)
But loft is still heat trap. heat from room rises, can't circulate due to half wall. Do those windows open? Of course not who would want windows that open? Vents thru wall above windows, dampered, thermostatically controlled. But will loose heat from room. Fans above wall, not ceiling fans, to push air back down or fans in loft floor registers would help circulation.

 

[slownsteady]

I'm surprised your condo association will let you do anything to the roof or walls beyond the paint.
If your unit is a standalone, maybe you could try something. But then again, what you do to the vents may affect your neighbors.
Years ago, I was in a loft that had a recirculation fan (don't know the real name for it) which was basically a fan fitted into a long vertical tube that stretched from the loft down to the first floor. It would not eliminate the heat from your condo, but it would move it around, cooling the loft somewhat. More efficient than your typical Hunter Douglas ceiling fan.

 

[Wuzzat?]

So with a loft you are working against the Stack Effect.

I've heard 5 to 60 Air Changes per Hour (ACH) with avg. 10 ACH being
recommended for this application. The conversion from room volume to CFM is not too difficult. The air intake area should be 4x the area swept out by the fan blades.

Experiment first with a box fan to see what kind of temp. reduction you can get. The fan maker can help you with what kind of CFM you can expect.

Also check to see if your outlets can support a window AC. If a 1 kw room heater or toaster doesn't pop a breaker you might be good to go on this.

Here's your cooling degree days for Anaheim.
http://www.weatherdatadepot.com/?pi_ad_id=6251685145&gclid=CP-JvIDgxLICFcne4AodG2cAwQ

An additional constraint could be fan noise.

 

[notmrjohn]

"a fan fitted into a long vertical tube" I like slow's idea, even if we don't know its name.:trophy:

All that venting and blocking of attics isn't going to help much with Wuzzat's Stack Effect, that I called a heat trap. Air flow thru cathedral could help prevent some heat transfer from up there. But attic ventilation is really more for moisture control, insulation stops heat transfer.
Tube could be disguised as pilaster or column with inlet register, outlets with dampers in loft. Sound insulated tube and fan isolating mounts would cut down on noise. Slownsteady fan even quieter. Carry tube up near ceiling, get some air to move out of top corner. Strong flow from tube against short wall would help overcome damming effect. And don't think it would violate any condo rules. If condo cops are even aware of it.:hide:

 

[Wuzzat?]

And if the downstairs is cool enough the OP could have a fan pushing air down into the downstairs through a tube. The hot air rising doesn't need a fan.

The thing with the tube is, you don't want to defeat firebreaks and somewhere I saw a tube damper that closes when it detects excessive temps. as would result from a fire. The bimetallic element acts a motor for the damper plate.

This firebreak thing is kind of what's keeping me from putting in a between-joist laundry chute from an upstairs closet floor to the downstairs laundry room ceiling.

You can do it, we can help!

 

[notmrjohn]

Laundry chute; spring loaded, fire resistant "damper", weight of clothes opens it. Damper close to opening so you can push thru stuck over alls, push flap open for lighweight Victoria's Secret dainties. Don't think there's really enough room inside walls though, you'd have to build it out some. opening high enuff so kid can't crawl through and play with matches after landing on soft clothes.

To my mind, or whatever it is I have in place of one, cold air should go up. Loft already warm, pulling air out of it means more warm air at ceiling level moves in. Cool air coming up pushes warm air out of loft. Pulling air down would mean cooler air at floor level, which warms and rises. Using tube with registers at various heights in loft, including one near ceiling, various directions, and adjustable dampers, in winter close off registers that might blow on occupant, send air against ceiling to blow out down slope under ceiling pushing warm air down wall to mix with cooler air below. Like winter time reversed ceiling fan. Reversible, multi speed fan?

 

[GBR]

So... what did the C.A. let you do almost 8 months ago?

Gary