Thread: Soffit blocks

This picture is in a new home, attic vented with ridge and soffit vents.

The builder advised that the AHJ required him to place blocks in the rafters (leaving a 1 inch space at top) to prevent wind blown snow from entering the attic via soffit vents. He said this was the code???

I like the idea of these, but Is anyone aware of a code requirement for these?

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He is probably interpreting a section that looks like this in the Codes due to the size of lumber used. It is to prevent lateral movement of the rafters.

Floor, attic and roof framing with a nominal depth-to-thickness ratio greater than or equal to 5:1 shall have one edge held in line for the entire span. Where the nominal depth-to-thickness ratio of the framing member exceeds 6:1, there shall be one line of bridging for each 8 feet (2438 mm) of span, unless both edges of the member are held in line. The bridging shall consist of not less than 1-inch by 3-inch (25 mm by 76 mm) lumber, double nailed at each end, of equivalent metal bracing of equal rigidity, full-depth solid blocking or other approved means. A line of bridging shall also be required at supports where equivalent lateral support is not otherwise provided.

And then he is applying this or similar in the Codes.

Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof framing members shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain. Blocking and bridging shall be arranged so as not to interfere with the movement of air. A minimum of 1 inch (25 mm) of airspace shall be provided between the insulation and the roof sheathing. The net free ventilating area shall not be less than 1/150 of the area of the space ventilated, with 50 percent of the required ventilating area provided by ventilators located in the upper portion of the space to be ventilated at least 3 feet (914 mm) above eave or cornice vents with the balance of the required ventilation provided by eave or cornice vents.

This is not from your code, I just grabbed it from the Florida Code that was handy and was made from the IBC and IRC. All of the codes were similar on this issue for quite some time now.

I'm thinking the AHJ may be related to the one here in NC that was requiring the contractor to caulk all roof wall intersections (siding to roofing)! They ain't all rocket scientist.

You mean like this Code section Vern?

Exterior and Adjacent Walls. Exterior and adjacent walls shall be sealed at the following locations:
1. Between windows and doors and their frames;
2. Between windows and door frames and the surrounding wall;
3. Between the foundation and wall assembly sill-plates;
4. Joints between exterior wall panels at changes in plane, such as with exterior sheathing at corners and changes in orientation;
5. Openings and cracks around all penetrations through the wall envelope such as utility services and plumbing;
6. Between the wall panels and top and bottom plates in exterior and adjacent walls. In frame construction, the crack between exterior and adjacent wall bottom plates and floors shall be sealed with caulking or gasket material. Gypsum board or other wall paneling on the interior surface of exterior and adjacent walls shall be sealed to the floor; and
7. Between walls and floor where the floor penetrates the wall.

Originally Posted by JeffGHooper

You mean like this Code section Vern?

Exterior and Adjacent Walls. Exterior and adjacent walls shall be sealed at the following locations:
1. Between windows and doors and their frames;
2. Between windows and door frames and the surrounding wall;
3. Between the foundation and wall assembly sill-plates;
4. Joints between exterior wall panels at changes in plane, such as with exterior sheathing at corners and changes in orientation;
5. Openings and cracks around all penetrations through the wall envelope such as utility services and plumbing;
6. Between the wall panels and top and bottom plates in exterior and adjacent walls. In frame construction, the crack between exterior and adjacent wall bottom plates and floors shall be sealed with caulking or gasket material. Gypsum board or other wall paneling on the interior surface of exterior and adjacent walls shall be sealed to the floor; and
7. Between walls and floor where the floor penetrates the wall.

NO, I mean sealing siding to shingles with caulk!

I misunderstood you. Sorry.

I cannot even envision a condition where that would occur, since flashing is required at every edge of a shingle application and abutment flashing at walls with a minimum separation between siding and shingles.

Do you mean where siding is placed down to a shingle deck?

If so there should be a 2" space where you see the step or wall abutment flashing.

What are they doing, cutting off the entire end of the caulking tube and rubbing it in with a softball?

Originally Posted by JeffGHooper

I misunderstood you. Sorry.

I cannot even envision a condition where that would occur, since flashing is required at every edge of a shingle application and abutment flashing at walls with a minimum separation between siding and shingles.

Do you mean where siding is placed down to a shingle deck?

If so there should be a 2" space where you see the step or wall abutment flashing.

What are they doing, cutting off the entire end of the caulking tube and rubbing it in with a softball?

You are correct. Contractor was on site when I called it out. He told me the AHJ made him caulk the joint. I felt sorry for him but at the same time could not understand why he did not challenge the AHJ before doing it. It was cement board siding (Hardie Board) caulked to the shingles. Happened several years ago and have not seen it since.