# Adding Microlam to garage, to support 2 doors and storage???



## 'Andyman (Sep 5, 2005)

*Microllam Joists*

Shannon,

I think the 18” deep joist is excessive for your requirements. Having said that, to comply with building codes, I would consider this storage space as being similar to uninhabitable attic space used for storage. Most codes, and I suspect New York’s call for a design live load of 20 lbs./sq.ft. The dead load would be the self weight of the joists and the plywood floor. Total load, 6 lbs/ft for the joist, 1.5 lbs/sq.ft. for the plywood and 20 lbs/sq.ft live load = 49 lbs./lineal ft on each joist. (40lbs live load, 9 lbs dead load) This is based on a strip load of 48 sq.ft. ( the area each joist supports) for a 24’-0” span and 2’-0” joist spacing . 

However, different manufacturers joist specs, taking into consideration the mechanical properties of the wood species used, will show slightly different spans and spacing for the loads.

Looking at Microllam specs, a 1 ¾” wide x 11 ¼” deep joist is good for 56 lbs/lineal ft total load and 41 lbs/lineal ft. live load. Where you intend to hang the garage doors, I would suggest bridging the bottom chords of two joists and hanging from there so that you distribute the additional point loads imposed by the doors over two joists.

To see the info I used, go to :

http://www.ki-lumber.com/engineered/TJI/2020.pdf#search='microllam%20lvl%20beams'

and download the .pdf file. Page 8 shows the load tables for various spans.

Hope this helps.


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## jbserra (Dec 14, 2006)

Wow, great information. I would like to do the exact same thing. I am really green when it comes to spans and loads.

Question, picture a garage 20 feet deep, 20 feet wide. Standing at the garage door looking in, can I run microlams at 8-10ft intervals left to right, and then run 2x8s front to back at 24" intervals in between the microlams? Will the microlams be able to support the 2x8s without any additional support from above or below? Maybe I can draw it:

2ft
|-|
__________
| | | | | | |
| | | | | | |
|mmmmmm| --
| | | | | | | | 8ft
| | | | | | | |
|mmmmmm| --
| | | | | | |
| | | | | | |
|mmmmmm|


m=microlam
|=2x6 or 2x8

With the cost of microlams, I can't have them every 24" left to right spanning 20ft a piece.

I would like to put drywall under, and insulation and storage above.

Is there ANY hope this could work or will I have to bite the bullet and span microlams left to right the whole depth of the garage?

Thanks!


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## mighty anvil (Oct 5, 2005)

*beam design*

I can't tell what you are supporting or what the tributary loading area is or what the doors might weigh so I can't tell you what you need but LVL's in NY state must be designed by an engineer. An engineer's certification can be provided by the manufacturer of the LVL's possibly through Home Depot. You can size them with a manufacturer's chart but the building department is required to ask for a stamp so why try to size it yourself? 

jbserra, if you are only spanning 20' supporting storage why not use 2x12's @ 16" o.c.?


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## ncgrogan (Dec 3, 2006)

You can't just size beams without knowing the exact situation they are going to be used in. You say there are no hurricanes or earthquakes where you are, but that does not matter. There are earthquake and wind uplift factors for the entire U.S. and they should not be ignored. Structural Engineering is not for a DIY in my opinion. The beam size is going to be dependent on the location of the loading, not just the magnitude as was mentioned above. You can't design a beam just on moment capacity for continuous loading as that chart does. You have to consider shear, torsion, connections, etc. and those are all contigent on how the floor and doors are posistioned and constructed. Hire a licensed engineer or have home depot some shop drawings for the project and have the manufacturers engineers do the calculations. Do what you want to, but owner/contractor modifications to buildings is one of the more common causes in building collapses. I'm not saying your house or garage is going to collapse, but at least you've been given fair warning that structural modifactions should be left to licensed engineers. There is a reason it's common place for structural engineers to have masters degrees in engineering , not just a bachelors. FWIW


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## Markustay (Oct 19, 2011)

New Member here - I found this thread because I am looking for a rough idea if something is possible, before I even buy the house.

I just have to comment on the OP - a little over a month ago, we had BOTH an Earthquake and a Hurricane in NY within two weeks of each other! Just goes to show, you can't count on nature to be cooperative when you do your Home Improvement. Sorry about the threadomancy.

Great Forum BTW - I will be picking through it from now on.


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## ddawg16 (Aug 15, 2011)

Sizing the beam for the span is the easy part.......your bigger problem is the footing and posts to support said beam(s). You can't just toss up a beam and hang stuff off it without taking into consideration the foundation. 

To illustrate....I have a 20x25 2-story garage. I have a 7x16 PSL beam spaning 20' across the middle of my garage. Holding that beam is a 4x6 post on each end. And under each post, my stem wall...which is sitting on a 3'x3' concrete pad 24" thick.

I'm willing to bet that the foundation for your garage is not designed for the kind of loads your talking about. Of course, if your the proverbial DIY'er who doesn't plan on getting engineering or pulling permits, you can do what ever you want.


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## Ron6519 (Mar 28, 2007)

jbserra said:


> Wow, great information. I would like to do the exact same thing. I am really green when it comes to spans and loads.
> 
> Question, picture a garage 20 feet deep, 20 feet wide. Standing at the garage door looking in, can I run microlams at 8-10ft intervals left to right, and then run 2x8s front to back at 24" intervals in between the microlams? Will the microlams be able to support the 2x8s without any additional support from above or below? Maybe I can draw it:
> 
> ...


You should start your own thread on this. Inter mingling threads is confusing and not polite.


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## Gary in WA (Mar 11, 2009)

Especially on a* 6 year old *thread....

Gary


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