how do I support a ridge beam with a microlam

onyx 1

I'm presently thinking about blowing out the back wall of my house and extending into the screened in room . I figured everything out with the exception of supporting the ridge beam over the existing rear wall. I was told I would have to install a microlam or other beam from side to side of my house with a post to the ridge beam. The span would be about 25'. It has a vaulted ceiling with a roof pitch of about 4 in 12. It has 1 roof layer constructed on 1/2 plywood and 2x8 roof beams.
Could someone help me out with the calculations or point me in the right direction.

jaros bros.

Step 1: Call your local lumberyard and they will come out and size it for you.

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Josh Jaros Remodeling in The Woodlands, Texas
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Daniel Holzman

I had a very hard time understanding your post. As I understood it, you are planning to remove the back wall of your house, and extend the house into the screened porch area. I did not understand whether you plan to install a ridge beam that would cover the entire house, including the screened porch area, or whether you have an existing ridge beam that you planned to lengthen, or perhaps you were going to install an additional ridge beam for the expanded part of the house.

I also gathered that you were considering supporting the (possibly new) ridge beam on one side using a post attached to a newly installed microlam beam. I was not clear if you were looking for help designing the new transverse microlam beam, the post off the microlam, the (possibly new) ridge beam, or all three structural elements.

In any case, you should provide a clear, scaled drawing showing existing conditions and proposed conditions. This project may require a structural engineering stamp, you should check with your local code enforcement officer.

Gary in WA

While at the building department, verify the screened porch has the required footings, foundation stem wall, and sized floor joists to support the new loads, to satisfy your Insurance carrier. Very handy in case of a claim or future house sale.

Be safe, Gary

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onyx 1

The house has two existing ridge beams one on inside the house the other in the screened room I'm trying to figure out a microlam beam to replace the existing wall and support the splice at the existing ridge beams. The post isn't a problem. It is sizing that microlam. Right nowI'm loking to get more of an idea of size and if needed later I will get an engineers input if I do decide to remove the wall.

tpolk

if the clear span is 25' you may want to look at a steel I beam. Many times they will not need to be as massive as a wood beam of the same deflection strength and can be cheaper.

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The older I get the better I was

onyx 1

Anybody with a little more help on this one would be great

thanks

Rory Read

Onyx,

What everybody is saying is valid. This is not something you could or would even want to pull off without permits, plans and engineering. Now that's out of the way.

There are two articles at the UMass Amherst Building and Construction Technology site that you might want to start with:

http://bct.nrc.umass.edu/index.php/p...g-span-tables/

http://bct.nrc.umass.edu/index.php/p...s-and-headers/

You will have to work through your own house's dimensions and your local code books to figure the load that your new beam would be carrying.

Like the other responders to your question, I am not clear as to what the new beam is picking up. If it had nothing to do with the porch but was just holding up the rafters coming of the vaulted ceiling in the main house, and if it was the same length or less than the beam in the vaulted ceiling, and if that existing ridge beam was sized correctly, then your new beam might not be any larger than the current ridge beam. But that's a lot of "ifs" to get to a "might."

If the new wall header beam is also carrying half the load of the porch roof system because the porch is also vaulted, then the beam is going to size up from there, and you will have to work through all the tables to figure the load off the porch roof system and add that to load coming off the main house. If the porch is not vaulted and is built with a ridge board instead, then you may not be adding load from the porch at all. More ifs and maybes.

If you did figure all the loads out, you could size the engineered beam using tables available online from beam manufacturers.

The other responders are also calling attention to the fact that it's a lot more than the beam you will have to work through. For starters, it sounds quite likely that you would need some burly footings under the ends of this thing.

Sharpen your pencil, and good luck,

Rory
RDG Read Development LLC
Portland, OR

Scuba_Dave

For my addition roof with a 24' 6" span they spec'd out (3) 16" LVL's as a structural ridge beam for a full cathedral ceiling in the attic
Each one weighs close to 200 lbs
I opted to put rafter ties in the attic instead for a 9' ceiling

You need to have this beam engineered for your specific load
Many lumber stores that sell LVL's will be able to do this load calc for you
My lumber co spec'd it out & send the plan out for an engineer stamp - free