[paulmars]

House built 1952. A few rafters cracked and one is split. Im considering adding supports. Advice?

4 pics: DIYnot > Network

Tks,
Pa

[dannac]

This may not apply to your area or situation, but in general.

[paulmars]

tks. My joists go the other direction. I have been installing collar braces and vertical supports. Throughout the attic. However, I thought that these splits/cracks needed something more, like maybe sister 2x6s.

tks
p

Why is the 90° better on the top opposed to the bottom, like I have done. I send post more pics.

[creahands]

The support wall going to the floor joists should be within a foot of the supporting wall/bearing wall. This will minimize stress on on floor beams and transfer most weight to wall.

Collar ties are usually installed at 1/3 of height down from ridge. Example: if ridge is 9 ft from floor then collar ties are 3 ft from ridge.

The knee wall supporting rafters at 1/3 up from floor. This will give best support to rafters.

The cracked rafters should be sistered and bolted together.

Chuck

[ma0641]

Agree with Chuck.

[paulmars]

What are the best strongest screws to use?

[ma0641]

For screwing sisters in, you can use drywall screws or deck screws, they have very high tensile strength. For ultimate connection strength use bolts.

[paulmars]

I've looked at the specs on the boxes of drywall at HD and they were the weakest that listed specs at all. Im sure many that had no specs were weaker, but still, Id like stronger. It's a toss up simpson or grk rss.

[creahands]

I would use 1/4'' bolts 2 feet apart and 1'' from the edge. Screws may shear after a time from the movement of the wood.

Chuck

[paulmars]

What type bolts, they have specs too.

P

[creahands]

Carriage bolts with a washer on the nut side

Chuck

[paulmars]

What's the best grade bolts to use for two 4' sisters, one each side of the 1st crack (wood knot)? I think four bolts would be good. Washers too.

[creahands]

Just so we are both on the same page. A sister is a full length beam that is attached to existing. What you are describing is call a scab. It will work fine on the knot.

Chuck