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This is a follow on question from here:

Floor joists connection to eaves

Since this question, I have been told I need 8" joists for my span and I have exposed my eaves area to see what space I've got.

Not much. From the face of the brick (internally) to touching the felt going out, just over 3". From the inner face of the brick to touching the felt going up, just over 3". I basically have a triangular space with 3" depth and height.

enter image description here

From what I can guess, this doesn't seem like enough space to try and fit an 8" joist into. If I cut the joist to fit that gap I believe I simply wouldn't have enough material in play to resist shearing stresses.

What I am after is something like a reverse joist hanger. Hangers hook onto a receiving entity and hold the joist in a cup.

What I need is something like a joist splice as shown here:

http://www.joist-repair.co.uk/

But that instead of connecting two joists, simply connects on the end of a joist and extends outwards. I've drawn what I'd like to try and find:

enter image description here

My theory being that a steel bracket occupying the small space will have much better strength than the joist with little material. So basically, it's some form of extension bracket.

Is there any such device or other way to solve this issue without affecting changes to the eaves area of the roof?

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I'd consult an engineer and then go to a fabricator to build exactly that for you. –  DA01 Oct 27 '11 at 14:45
    
@DA01 Yeah I was thinking about fabrication, in that case as you say I'd need someone to run the numbers for me. –  Adam Houldsworth Oct 27 '11 at 14:47
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1 Answer 1

up vote 5 down vote accepted

enter image description here

There is a simple answer to this. Cut the angle matching the roof on the ceiling joist, slide it in on top of your wall and attach it to the side of the rafter. Then attach them together with small lags or carriage bolts. If you look at your picture the 8" joist will be in contact with the rafter well beyond your walls. The rafters will help carry the weight of the floor joists through the rafters down to the walls.

Don't worry about the rafters, you will be applying the weight soo close to the wall it will not put more stress on your rafters.

Construction adhesive would be a good idea too. Your Lag spacing may vary depending on the thickness of your rafter. Keep lags 2" from all edges and 3" from each other. Pre drill all the holes you don't want to risk splitting your rafter. Lags should be 3/8" or less. There is also of high strength screws/ lags that are smaller but just as strong as a standard lags that would work good.

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That's not a bad idea, I need to confirm the dimensions of my rafters and get back to you. With the minimum distance you've specified, I don't know how many bolts I can get in. I'm fairly certain that if I place the bolt in the centre of the rafter it will be with 2" from both edges already :-( –  Adam Houldsworth Oct 27 '11 at 18:57
    
I've decided to take this approach in conjunction with sistering a small section of joist in parallel with the main beam in order to get more material on the brickwork - all bolted together. –  Adam Houldsworth Oct 31 '11 at 9:00
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