Author Topic: Room additions  (Read 4744 times)

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Offline devildog

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Room additions
« on: September 18, 2009, 02:03:47 PM »
I was wanting to know if anyone has added a room to the side of one of johns plans ,that wasnt on the plan . and if you did, was it approved by the building official without having to get an engineer to redesign it?
I have the VC plan,and it has a12x14 addition . But since our plans keep changing ,and my wife would like alittle bit larger house. We currently live in a700sq ft mobile home(4yrs now) with no storagespace and there is 3 of us , and this will be our permanant home.

Ive heard terrible stories of costly engineers upgrading plans,and would like to avoid this. what id like to do is purchase the20x30 1.5 story and add a 12x16 shed roof as a bedroom on the side. the building official for my area said when talking about the VC "as long as you have plans you hve no problem". In my oppinion, if  I have plans for the house and build the addition to code, there shouldnt be any problem.

 Im getting ready to take bids on a crawlspace foundation and need to get this figured out.Im calling the B.O. next week to talk to him about it, and just wanted to know if anyone has added to the plan, and what your experience was. Or maybe someone involved in construction has. thanks Darrell.

Here is pic of what I want to do exactly except w/ 20x30 as main structure.



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Offline devildog

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Re: Room additions
« Reply #1 on: September 18, 2009, 02:06:37 PM »
the picture is the 16x28
Some people spend an entire lifetime wondering if they made a difference in the world. But, the Marines don't have that problem.
Ronald Reagan, President of the United States; 1985

Offline John Raabe

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Re: Room additions
« Reply #2 on: September 18, 2009, 04:32:55 PM »
In the design of the shed roofed addition you are adding an additional load on the sidewall of the 16' wide cottage. The inexpensive way to build that at the foundation is to have a beam with 2 or 3 spot footers under it to carry the wall above and 1/2 of the shed roof addition load. Someone will have to size that beam and the footers (doesn't need to be an engineer or be expensive, but it will need to be someone who knows the local loads). This person can also size the rafters for your addition roof. The rest of your foundation would be the concrete crawlspace footing detail. You could also run the floor joists the 12' span direction and use the span chart link on this site to size those. That also adds 1/2 its load to the beam mentioned above.

If you were to do a gable roof (most easily done with trusses) that bear on the two sidewalls of the addition, then you are not adding new loads to the sidewall of the 16' wide cottage.

If you want to get the plans for the expanded floorplan worked out without hassling it yourself, check in with a local building designer for help.
None of us are as smart as all of us.

Offline Don_P

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Re: Room additions
« Reply #3 on: September 19, 2009, 05:48:41 AM »
I think this is what John is proposing. I put one pier under what looks like a loft post support to carry that point load straight down thru a pier then divided the remaining span in half. I drew in a triple 2x10 dropped girder spanning that resting on pilasters at the ends.

I've very conservatively interpolated from table R502.5(1). Its not quite a fit but he would probably go for it.
Table 802.5.1(3) and (5) are our rafter tables.

This pic is the way I would do it, another row of piers down the center of the main house and breaking that floor span in half, again a tripl 2x10 girder.

Offline John Raabe

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Re: Room additions
« Reply #4 on: September 19, 2009, 06:23:38 AM »
Helpful diagrams Don and perfectly valid analysis.
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Offline Don_P

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Re: Room additions
« Reply #5 on: September 19, 2009, 07:58:01 AM »
Well close  :-[
 Looks like I need to move one of my main house piers under the loft edge to support a post there as well.

Offline devildog

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Re: Room additions
« Reply #6 on: September 19, 2009, 08:37:41 AM »
thanks John, and Don for your help and the illustrations.  I'll talk to the building official next week to see what he says, he seems very laid back.

don did you mean there should be a pier directly under the loft beam? im not sure what all these plans detail because I havent purchased them yet. I wanted to make sure this would fly before dropping more money on plans.
Some people spend an entire lifetime wondering if they made a difference in the world. But, the Marines don't have that problem.
Ronald Reagan, President of the United States; 1985

Offline Don_P

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Re: Room additions
« Reply #7 on: September 19, 2009, 10:55:28 AM »
I'm just working off your drawing, it looks like the loft beam is supported at 3 points, the crawlspace wall, a pier under the short girder and a pier along the midline of the main house.

 

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