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Rafter detail for added insulation

5813 Views 29 Replies 8 Participants Last post by  EricBrancard
Does anyone see any issues with this rafter/plate detail? Code says just 1.5" bearing required. It raises the height of the building, which is fine.

As long as I run the ceiling joists out, there is plenty of overlap area for the 14 nails required at the rafter/joist connection.

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If raising the roof height is not a problem, I sometimes put a rim on the ceiling and add a plate on top of the ceiling and rim. This gives you lots of room for insulation. You could add a little more overhang if the fascia height is a problem. In many years of hand framing roofs I have only had one inspector question my methods .
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If raising the roof height is not a problem, I sometimes put a rim on the ceiling and add a plate on top of the ceiling and rim. This gives you lots of room for insulation. You could add a little more overhang if the fascia height is a problem. In many years of hand framing roofs I have only had one inspector question my methods .
We almost always place the rafters on the floor joist box. Floor joists, plywood, plate, rafters.
This is an uninhabitable attic. But I see how this could work, you just need a connection equivalent to the rafter/joist connection to connect the rafter to the plate or plywood. H2.5 type strap. This roof requires 14 nails.
If raising the roof height is not a problem, I sometimes put a rim on the ceiling and add a plate on top of the ceiling and rim. This gives you lots of room for insulation. You could add a little more overhang if the fascia height is a problem. In many years of hand framing roofs I have only had one inspector question my methods .
I agree with this. I have never framed it this way myself but have seen it in many houses around here. Bump up the ceiling joists size for even more insulation space. If you're building a new roof though I'm sure the engineer or architect will ultimately decide. But you can suggest this to him.

Exterior proportions are the biggest issue with this. May have to do something to make sure it doesn't look like the fascia is way too high. Bigger overhangs or higher windows maybe...
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Too high looking fascia is a common issue, since 24" energy heel trusses are common. This is a little cabin project (times 2). Out of the city limits, no engineer or inspections, but that doesn't really change how I'd build.
Exterior proportions are the biggest issue with this. May have to do something to make sure it doesn't look like the fascia is way too high. Bigger overhangs or higher windows maybe...
This will also hinge on the height of the studs and the roof pitch.
You clearly are aware of the issues at hand so I would definitely build it with a plate on top of the joists. The style will dictate how you keep the proportions looking good. May have to draw a pretty detailed exterior view in order to decide how to rectify the fascia being higher.

If you are not fluent with sketch up or some other program it may be worth paying someone to draw an exterior view for you. It will be easier to play with and visualize the subtle changes that could make or break the look.

Nothing worse than finishing the exterior and realizing you should have used taller windows and a smaller frieze...
This will also hinge on the height of the studs and the roof pitch.
True. This is twice you've responded before me because I type so damn slow on my phone.
Why would you need to increase the ceiling joist size, if it is a attic/ just add the insulation there! Do the correct size joists as needed for the span/ etc. Put a 2x4 on the ceiling joist, and a small birds mouth, will help with the holding. Just my thought!
Why would you need to increase the ceiling joist size, if it is a attic/ just add the insulation there! Do the correct size joists as needed for the span/ etc. Put a 2x4 on the ceiling joist, and a small birds mouth, will help with the holding. Just my thought!
With 2x10 walls he is clearly trying to make this super insulated. The taller ceiling joists help to add a couple inches of insulation at the perimeter of the building. This is a classic weak spot for insulation as the roof deck always limits insulation height here as opposed to the middle of the attic.

But you are right, it may not justify the added cost.
Lay it out on a piece of PLYWOOD< done that hundreds of times, as needed! Then you can see, cut, and do as NEEDED!! DID I miss something here? Is this the DIY network?
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I've made this mistake before (out of proportion facade), your comments are making me think the added insulation is hardly worth it. I can model the energy savings and it's almost nothing. We just get obsessive about eliminating the "weak links" in the building envelope, but sometimes the benefits are too minimal.

That said, I still enjoy this discussion about options when it will work visually. Trusses rule here but for little projects like this I enjoy the occasional cut and stacked roof.
I've made this mistake before (out of proportion facade), your comments are making me think the added insulation is hardly worth it. I can model the energy savings and it's almost nothing. We just get obsessive about eliminating the "weak links" in the building envelope, but sometimes the benefits are too minimal.

That said, I still enjoy this discussion about options when it will work visually. Trusses rule here but for little projects like this I enjoy the occasional cut and stacked roof.
What is the insulation detail for the roof? Is it a vented assembly with FG?
What is the insulation detail for the roof? Is it a vented assembly with FG?
vented eaves and gable vents, cardboard baffles, 18" cellulose where possible.
Updated sketch with what's being proposed here. What's your preferred method of meeting the heel connection requirement to withstand 1300 pounds, in this case, of force? It's easy when you're face nailing rafter to joist.

Simpson LTS/MTS/HTS is what I'd normally see, usually nail through floor plywood into ceiling/floor joist. In this case just ceiling joist.

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Updated sketch with what's being proposed here. What's your preferred method of meeting the heel connection requirement to withstand 1300 pounds, in this case, of force? It's easy when you're face nailing rafter to joist.

Simpson LTS/MTS/HTS is what I'd normally see, usually nail through floor plywood into ceiling/floor joist. In this case just ceiling joist.
We bring the sheathing up to the plate the rafter is sitting on so it's tied in all the way. Then a combination of toe nailing and Simpson connectors is used to meet requirements.

There was another thing that one of the building departments requested in the past, this was before I was on my own. They wanted strips of 3/4" plywood or 2x4s nailed to the side of the rafter, run down behind the plate and then fastened to the floor joists. I'm wondering if this requirement could have just been met with a Simpson strap.
We bring the sheathing up to the plate the rafter is sitting on so it's tied in all the way. Then a combination of toe nailing and Simpson connectors is used to meet requirements.
I would too, I drew it kind of stupid:laughing: My right middle finger is all butchered and wrapped up so drawing is a little chore anyway.
Does anyone see any issues with this rafter/plate detail? Code says just 1.5" bearing required. It raises the height of the building, which is fine.

As long as I run the ceiling joists out, there is plenty of overlap area for the 14 nails required at the rafter/joist connection.
2x10 wall? Added insulation yes. take into account thermal bridging and what not.. use ICF man
2x10 wall? Added insulation yes. take into account thermal bridging and what not.. use ICF man
Could use a staggered stud wall too.
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