Can I remove bird blocks?

[a57oval]

Hello all,

First of I am a homeowner and a newb to this forum. Please excuse my lack of knowledge in this area.

I am looking to drastically increase my air intake at the soffit. I came up with the idea of removing about 1/2 of the bird blocks, sheeting the underside of all the eaves(?) and installing a continous soffit vent.

I live in the pacific Northwest (Seattle WA area) and have been told different things by different people. 1 contractor has told me that the bird block are not necessary. Another contractor has told they are a structural componenet of the house and must stay.

I am lost. How should I proceed? I don't know which contractor is right. Can you guys shed some light? Thanks for any advice you can provide,
Peter

[Don_P]

They do improve the structure by helping to prevent the rafters from rolling over, however most houses do not have them, the fascia is also preventing roll. They are also preventing air from washing into the lower part of the insulation and reducing it's effectivenesss. Can you drill holes in them up near the roof sheathing... best of both worlds?

[a57oval]

Don P, thanks for responding.
I had thought about drilling more holes in them but was concerned about compromising the integrity of them. Currently they have 3 2 inch holes in each one. Another idea I had was to remove every other bird block and in those spaces and install a 2x4 down at the fascia. Between adding the 2x4 at the fascia, the existing bird blocks, and the new sheeting I will be adding to the eaves will I have done enough to maintain the integrity of the structure? Can I just remove them and not worry? Still confused,
Peter

[Don_P]

You can put me in the removal camp. I would install hurricane ties while you're up there if it is old enough not to have them. I've never seen a rafter roll but I've sure seen some roofs in the next field over.

[a57oval]

Don P,
Thanks again for responding. My house was built in 1989. Can hurricane ties be retrofitted without removing siding? I will do some googling on these. Thanks for your input. Anyone else? I would love to know if the bird block is a structural component of the house and if it is required.
Peter

[WireMan]

most under side of eaves in this area, that i have noticed, other than a brand new build, are not "closed" or covered, with soffit board. there for you see the bird blocks alot. To you guys that closed soffit is a standard, is bird blocking still used if you constantly use the soffit board and soffit vents? in that case is it really more less to keep the insulation in place at that point? ( besides the rafter rolling part )

[Don_P]

No, it is not used if there is a boxed soffit. The insulators are supposed to use a baffle at the lower edge to prevent wind washing into the insulation. After diagnosing some problems I've taken to doing that with scraps of plywood to form bird blocking that stops an inch or so under the sheathing. With sprayfoam the entire area is blocked solid.
Most birdblocked, open soffit houses here are older with flat ceilings and gable venting.

[WireMan]

Most birdblocked, open soffit houses here are older with flat ceilings and gable venting.

exactly the case such as my own home.

But that spurs a question, in my shed i built, it has a gambrel roof, and i put a 2x6 "bird block" in to stiffen the rafters/trusses, (what ever the true term is) and there is a 1/2" gap between the them and the roof sheating, planning on using soffit board and continues vent, is that gap sufficient, or would you suggest drilling holes? the inside is ( or will be ) sheet rocked like a vaulted ceiling. and i do have a ridge vent the length of the structure.
Thanks Don.
WM
refer to this post for pictures : http://www.construction-resource.com/forum/showthread.php?t=9275

[Don_P]

You will be fine if its just a general purpose shed since there are no major moisture generating sources inside and probably less heat to hold and transport moisture.

[ChrisVJ]

General requirement for venting a roof is 1/300 of the roof area. If your holes amount to half that they should be fine but you need the other half near or at the peak.

If I am doing 2x10 rafters I use 2x10 offcuts as blocks but place them vertically on the top plate, then they count as one end of the interval for blocking and also leave about an inch at the top for vent.

If you are putting on soffit and vent then why not just cut more holes in the top edge of the blocks or open it out with sabre saw? (Won't hurt the blocks structurally, they can be as little as 4" deep and still be legal blocking but in this location you do need to protect all except the top 2" of the opening from cold air.)

My current house has solid soffits and 2" holes along the facia. Hideous. We're changing that for t&g soffit with continuous vent and new cedar facias.