rim joist construction

[MikeT]

I was talking with my building "mentor" yesterday (via telephone) about my project, and he told me that when I construct my rim joist, I should double up the joists next to the wall(s).  He said the inspector will want to see it done this way.  I am having trouble envisioning what purpose this serves.  My mentor said that it is just what the inspector wants...

Am I misunderstanding what he is talking about?  

[PEG688]

He may be refering to Dbling up the joist under  the interior partions , walls that run parrell to your joist. If they are bearing walls you will need to do this , there also would be a beam or pony wall (direct bearing) under the wall / Dbl. joist. These beams / pony walls  would be supported by your footings / piers depending on what type foundation you have / use.  

If they are non - bearing (normal interior walls) walls it will create issues with plumbing / elec. wiring / heating ducts , that want to run down into the crawl space / basement.


The idea of Dbl,ing up under the walls is good as those walls , if they fall dead center between the joist would only be held up by the 3/4" subflooring.   Althought if you put D/W on the walls it becomes some what like a box beam , not a true one , but still the D/W nailed or screwed to the studs adds support.

 If you had a wall that did fall dead center over a joist bay , cross blocking that bay would be a better option , IF it is a plumbing , heat duct , electrical wall.

 Long answer   Hope it make sense :-/    

[MikeT]

Well the way I understand John's plans for the Victoria's Cottage, every wall is a bearing wall (side walls support part of the roof and the end walls carry the weight of the roof beams via the posts).  So does that mean for each of the walls that run parallel to the joists, I will double up on the joists at the ends?

[PEG688]

He shows on the plan where the dbls go. And your right , almost , the wall the ref and toilet are on is  a non -bearing wall,  at  a glance the only non Bearing wall on the mani level.

 I gotta go to work I'll add more tonight if John doesn't clear things up today.

Later

[John Raabe]

Mike:

RE: Victoria plans. Are you talking about the lower floor framing when doing a post and pier fourndation? If so look at the Post and Pier Foundation plan sheet 3, the double joists are shown at the gable end walls and the beams are shown on the load bearing walls. (The gable end walls are loaded at the centers with the point loads.)

If you are doing the stem wall foundation there is a double joist wall shown under the bathroom/kitchen wall.

You do not need to double the joists under a full support wall or other places on that plan.

[MikeT]

Thanks to John and PEG for the prompt and helpful responses thus far.  I can understand the double joists at the bathroom/kitchen wall.  But I am simply framing the bedroom floor.  Under that is a continuous 4' stem wall foundation on top of which are sitting 4' framed walls (framed in 2x6s at 16" o/c).

It is not a big deal in terms of cost or hassle, but I just do not see the value in doubling up floor joists that rest on top of the walls I have made.  But if that is part of the quirkiness of the local inspector, I guess I should do it.

I will study the original plans again tonight.  Perhaps I overlooked something when I modified them.

mt

[John Raabe]

No, I just think your friend was thinking of some other situation. I don't think you will need to double under the walls you describe. What would be the benefit?

[Amanda_931]

Bathtubs are heavy--especially when they're filled.

Double joists--or lots of blocking--sound pretty good.  I've lived in a couple of houses with sagging bathtubs.