# Hip roof -- Ridge vent or fan?



## golem (Jul 21, 2016)

I'm getting differing professional opinions about venting my hip roof and would like to solicit yours. Some say ridge vent only, others say no ridge vent while keeping the vent fan. Only one has suggested ridge and hip venting (with no fan).

The ridge apex is a scant 3' long so based on ridge vent install guidelines I figure that would mean less than 2' of actual venting. Would prefer passive venting but not sure if additional hip venting would be be wise or cost effective. 

I installed the attic/roof fan about 10 years ago and it seems to work fine although it does run nearly continuously for about 7 months out of the year, have to assume it's a fair bit of kWh's. Replaced the motor once but most likely due to minimal soffit venting which I've since more than doubled at time of vinyl install.

Also attached a pic that shows cable stand-offs screwed into the shingles. There has to be a better way...suggestions?



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## nealtw (Jul 21, 2016)

Ridge vents on the hip could or would just provide a short circuit.
You could add a couple box vents but they would need some kind of flapper for when the fan runs so they don't create a short circuit.
I don't see any vents on the lower roof, if the fan is working for that roof too, I would isolate that and add ridge or box vent for that one.


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## golem (Jul 21, 2016)

Thanks for the reply *nealtw*!

Absolutely -- Ridge vent and no fan or vice-versa, no tug-o-war.

One-way passive in conjunction with a fan is an option I didn't consider. Thanks for adding another bolt to the quiver!

No, no venting on the lower roof aside from soffit and a single gable louver. That roof will definitely be getting a full length ridge vent at time of re-roof.

Just did a bit more research and, although I can't find many examples, a ridge in combination with hip vents is looking like a viable option. I have to wonder if an option (both operationally and aesthetically) would be to have the hip vents extend only half way down the hip peaks?


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## nealtw (Jul 21, 2016)

Close the gable vent it will short circuit the system.
Under the ridge vent you cut plywood away, say 2" by 2 ft and maybe 2 ft down each hip. Below that plywood is a ridge board or block that closes some of that gap so count on one inch.
So that might give you 120 sq. inches.
I have never seen ridge vents on a hip so I would limit how far down you went, as far as looks you could do the whole ridge with out cutting all the plywood.
Any more than a couple feet on the hip could effect the structure strength.
I would leave that roof as is and make the other roof passive. That should cut the fan use or cool the hip roof better.


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## nealtw (Jul 21, 2016)

After thinking about it, you can not do ridge on the hip, as the end of the sheet would not be supported.


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## Snoonyb (Jul 21, 2016)

Do not block the gable end vent because it's the venting relief for that roofed area.
The free space in the tie-in so minimal as not to affect the venting of the hipped roof area.

Instead install an exhaust fan there for that area.

The simplest solution is another exhaust fan.

Remember, these are temp. controlled, and you set the temperature.

Which then begs the question, how well are your attics insulated.

These exhaust fans are also available solar powered, so were I you, I'd do the math.

What are those cables for?


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## golem (Jul 21, 2016)

Appreciate the replies!

_I really didn't state previously so, just wanted to note -- Although I've done most of my own home improvements (windows, doors, siding, etc.) the roof is a job I prefer to sub for convenience._

As mentioned earlier one roofer did make a passing mention of ridge style vents on the hips. The following image is what had me musing the possibility of half-length vents. 
.




From what I can see the lower roof does not share a breezeway with the hip. As was stated by *nealtw* -- I was always under the impression gable vents combined with a ridge vent is a definite no no in most circumstances. 

Yes, the current vent fan is temp controlled. I've adjusted it a number of times but, while it does seem to effect duty cycle, it runs nearly non-stop during the warmer months.

The attic is not insulated well at the moment. Still has nothing more that 50 year old blown in at 4"-5". I'll likely be laying some batt next month, hopefully coinciding with the re-roof.

Location is Mid-Atlantic (Washington DC suburbs).


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## nealtw (Jul 21, 2016)

As I mentioned, there would be nothing holding up the end of the sheeting or ship lap.


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## Snoonyb (Jul 21, 2016)

Both gable and ridge vents are passive and are affected, as you found, by the area of the eave vents and keeping them open.

Given your temp. zone I'd add R30 unfaced, and you may find that your current venting is sufficient.

What are the cables for?


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## golem (Jul 21, 2016)

nealtw said:


> As I mentioned, there would be nothing holding up the end of the sheeting or ship lap.


I hear ya! Was just figuring there must be some sort of mitigation to the possible weakening. Maybe gusseting or simply intermittent perforation of the sheathing.

>>> A short article about hip venting.

.


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## golem (Jul 21, 2016)

Snoonyb said:


> Both gable and ridge vents are passive and are affected, as you found, by the area of the eave vents and keeping them open.
> 
> Given your temp. zone I'd add R30 unfaced, and you may find that your current venting is sufficient.
> 
> What are the cables for?



Yeah, I nearly tripled the eve venting when installing the soffits/siding. 

My local ELCO and county are providing incentives which gives nearly 60% back on product cost. I only have about 1,200 sq/ft. and the OC R30 unfaced that I figured I'd use is $559 a pallet. Two would do so I just have to call out to my ELCO's list of contractors to see whether I can get them to do it for the same price (after rebate) as I could myself (rebate is only for qualified contractor installs).

Sorry 'bout that. Those cables are COAX to an OTA HD antenna, rotary antenna motor power and, ahem, ground cable.


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## nealtw (Jul 21, 2016)

golem said:


> I hear ya! Was just figuring there must be some sort of mitigation to the possible weakening. Maybe gusseting or simply intermittent perforation of the sheathing.
> 
> >>> A short article about hip venting.
> 
> .



Not worth the effort.


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## Snoonyb (Jul 21, 2016)

I would think that through the attic or tight to the eaves would be an aesthetic solution for the coax an a driven ground rod will satisfy the lightning concern.

Unless of course, when the wind blows, there is a pleasing harmonic balance.


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## golem (Jul 21, 2016)

Snoonyb said:


> I would think that through the attic or tight to the eaves would be an aesthetic solution for the coax an a driven ground rod will satisfy the lightning concern.
> 
> Unless of course, when the wind blows, there is a pleasing harmonic balance.


Since the chimney (which the antenna is attached to) is just out of picture and basically in the center of the roof the cables must traverse the roof. The path they take now is nearly the shortest distance and decidedly most visually discrete since it is the rear slope of the roof. Was hoping there might be acceptable options aside from a weatherhead mast or conduit penetration flashing.


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