Ridge Vents w Box Vents

[DogwoodTales]

My roof has some box vents along the back side of the house, but I'm thinking of upgrading to a ridge vent.
The soffit has some vents, but I'll probably have that replaced with full vented soffit.
The roof is a hip roof, so no gable vents.

So if I do this ... do I need to remove the existing box vents?

thanks

[Snipe Hunter]

My roof has some box vents along the back side of the house, but I'm thinking of upgrading to a ridge vent.
The soffit has some vents, but I'll probably have that replaced with full vented soffit.
The roof is a hip roof, so no gable vents.

So if I do this ... do I need to remove the existing box vents?

thanks

No. While it isn't 100% necessary to remove them but it's not a bad idea to disable them. It's difficult to cap them off from the inside because there isn't much to fasten to except the roof sheathing. You could simply wad up some insulation and stuff it in the holes. Maybe cut a wood plug and jamb it in the opening. If you have sufficient soffit vents and a sufficient ridge vent, nothing else is necessary. But leaving the box vents open probably won't hurt anything. Plug the holes in the sheathing and toss the box vents when you get a new roof.

The soffit should be vented the entire length, Not just every couple feet. Do you have vinyl soffit? The ridge vent should run between the 2nd truss on each end of the gable.


I find it interesting when I go out west and new homes have box vents. They haven't been used for new construction on the east coast for probably 30 years with the exception of areas that ridge vents aren't feasible.. like porch "Shed style" roofs or shed style roofs on additions. Don't forget to install baffles for new soffit vents.

[DogwoodTales]

Thanks
Yeah, by remove I meant the whole thing and plugging up the holes. If necessary I have access to disable them. 
The roof is only 5 years old, so if I don't remove them the boxes will be there for a while unless there's storm damage or similar.
If it was my house at the time I would have had a ridge vent put on rather than the box vents. Maybe they were just re-using existing vent holes.
The soffit is aluminum and has like a 6x12" vent every 8 feet or so. I'd like to increase that to full vent around the house to improve air flow. Yes, I'm aware of using baffles. 
I have a pro that I would use to install the vented soffit. He'll get it done in a day or two, while it would take me a week and a lot of choice words.
The ridge vent is simple enough that I could tackle that in an afternoon.

[KC]

No. While it isn't 100% necessary to remove them but it's not a bad idea to disable them. It's difficult to cap them off from the inside because there isn't much to fasten to except the roof sheathing. You could simply wad up some insulation and stuff it in the holes. Maybe cut a wood plug and jamb it in the opening. If you have sufficient soffit vents and a sufficient ridge vent, nothing else is necessary. But leaving the box vents open probably won't hurt anything. Plug the holes in the sheathing and toss the box vents when you get a new roof.

The soffit should be vented the entire length, Not just every couple feet. Do you have vinyl soffit? The ridge vent should run between the 2nd truss on each end of the gable.


I find it interesting when I go out west and new homes have box vents. They haven't been used for new construction on the east coast for probably 30 years with the exception of areas that ridge vents aren't feasible.. like porch "Shed style" roofs or shed style roofs on additions. Don't forget to install baffles for new soffit vents.

Some builders in south Texas were still using vents as recently as two years ago in higher end custom homes.

[Snipe Hunter]

Thanks
Yeah, by remove I meant the whole thing and plugging up the holes. If necessary I have access to disable them. 
The roof is only 5 years old, so if I don't remove them the boxes will be there for a while unless there's storm damage or similar.
If it was my house at the time I would have had a ridge vent put on rather than the box vents. Maybe they were just re-using existing vent holes.
The soffit is aluminum and has like a 6x12" vent every 8 feet or so. I'd like to increase that to full vent around the house to improve air flow. Yes, I'm aware of using baffles. 
I have a pro that I would use to install the vented soffit. He'll get it done in a day or two, while it would take me a week and a lot of choice words.
The ridge vent is simple enough that I could tackle that in an afternoon.

If you remove them you'll have to fill in the sheathing holes with new OSB/Plywood sheathing. Remove the shingles around the area and install new underlayment and re-shingle the area. Lots of work and hope the new shingles match. I wouldn't do it.

[Snipe Hunter]

Some builders in south Texas were still using vents as recently as two years ago in higher end custom homes.

I see it out west. They can be used here in new construction as long as the house still has a continuous ridge vent and soffit vents. Local code here requires ridge and soffit vents assuming the home has a soffit. If not, other ventilation is requires like powered vents.

The problem with box vents is they are usually not installed near the ridge so the heat is still stuck in the ridge and they only vent the area around the vent and not the entire roof cavity.

If you put on a new roof here, it is required by the roofer to cut in a ridge vent at the bare minimum. Roofs don't need a permit but code requires the ridge vent.

My guess is they still allow them out west because the humidity is lower? Drying the attic cavity isn't as big a deal maybe? But still, heat and UV are the asphalt shingle killers. I find more mold in attics than I do anywhere else in the house and it's because of poor ventilation.

[DogwoodTales]

thanks guys.

Most likely I'll just disable the box vent and won't bother removing them, but if I eventually do they're on the back of the house and color mismatch won't be seen from anywhere near the house.
During a bout of insomnia last night I saw a video that explained why box vents should be disabled when putting in a ridge vent - because the air will likely circulate between the ridge and the box vent. Makes sense.

In regards to having a hip roof - a videos said a ridge vent is not so good on a hip roof, but I don't understand why not.
I have a ranch house that's about 57-60 ft long with probably a 35 ft long ridge. There is a hip that extends out over the front porch about 10 feet.
I would think I would be okay with a ridge vent at least on the 35 ft long run. No?

[Snipe Hunter]

thanks guys.

Most likely I'll just disable the box vent and won't bother removing them, but if I eventually do they're on the back of the house and color mismatch won't be seen from anywhere near the house.
During a bout of insomnia last night I saw a video that explained why box vents should be disabled when putting in a ridge vent - because the air will likely circulate between the ridge and the box vent. Makes sense.

In regards to having a hip roof - a videos said a ridge vent is not so good on a hip roof, but I don't understand why not.
I have a ranch house that's about 57-60 ft long with probably a 35 ft long ridge. There is a hip that extends out over the front porch about 10 feet.
I would think I would be okay with a ridge vent at least on the 35 ft long run. No? <- No

I'd stay away from that video. There is nothing better than a ridge vent and sufficient soffit vents. A ridge vent without soffit vents is worthless. The whole idea is air movement. Heat rises creating the movement from the soffits out through the ridge vent creating convection. Without vented soffits, there is no air movement. A little heat will escape but not the moist air in the space.

There is an alternative to a soffit vent. It's a Shingle Over Vent. But now you're back to new shingles. Vented soffits are much easier to install.

[DogwoodTales]

""I would think I would be okay with a ridge vent at least on the 35 ft long run. No? <- No""

That "No" was a little confusing at first. It took me a moment to realize that you thought I meant a ridge vent without vented soffit.
I have partly vented soffit, but it's ugly and probably grossly insufficient and so I will have that replaced with full vented soffit all the way around the house.

thanks for your responses to all

[taxman]

Interesting conversation. A few questions from a non-builder;

In South Florida (near Ft. Lauderdale) the roofers do not use ridge vents and seem unfamiliar when I discuss it. 

Due to the heat buildup in attic, I had several vents added and a thermostat controlled attic fan near the top of ridge.  Keeps the attic down to 90+/- degrees in summer. 

Any reason ridge vents are inappropriate in hurricane areas? or high humidity?

I followed most of the conversation, except the mention of baffles when discussing soffit vents. Is that the internal blocker so the insulation doesn't block the vent?  

Thanks,