Replies

1. 
   Guest_ | Mar 31, 1999 10:44pm | #1

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   Only questions Rob,

   Is the wall in question, load bearing? Is there a roof directly on this garage and which way are the trusses, if any, run? It there is trusses, and they are running the width, then you don't have a load and all will be fine.

   If this is the lower part of a built in garage ie basement entry, and you have living quarters above, then you shouldn't mess with the headers.

   Could you give some indications on the above and the actual composition of the headers, 2x10? and do't forget to tell us the size of the window..

1. 
   Guest_ | Mar 31, 1999 11:34pm | #2

   *If you are giving us a header size of 4"x16"x20'then my guess is this is a load bearing header. Or, in another way, the door is not on the gable end of the roof. Need some of the details that Gabe asked for but sure, you probably can replace the wooden header with a steel one of less depth with a column in the center. Have a structual engineer come and look at it and have him design a replacement given your constraints.Dave

1. 
   Guest_ | Apr 01, 1999 02:33am | #3

   *There are only two ways to reduce the required depth of a beam. 1. Reduce the load or 2. reduce the span. Since you will effectively be reducing the span by 1/2, you can reduce the depth as follows if you don't change the species or grade (greatly simplified): DEFLECTION is proportional to the cube of the span. Resistance to deflection is proportional to the cube of the depth. So if you cut the span in half you can cut the depth in half. BENDING is proportional to the square of the span. Resistance to deflection is proportional to the square of the depth. You can cut the depth in half. SHEAR is proportional to the span. Resistance to shear is proportional to the depth. You can cut the depth in half. Check the exact figures with an engineer. Remember there will be a considerable load on the column you put in the middle, so be sure you have an adequate footing (footer for those who have a regional preference.)

1. 
   Guest_ | Apr 01, 1999 05:12pm | #4

   *Rob, the simple answer to your simple question is yes!Make sure you properly size the newer, smaller headers correctly for the load that it is supporting. If a drastic reduction is needed, consider some type of manufactured products; lvl's, microlams, steel, etc.Blue

2. 
   Rob_Scott | Apr 02, 1999 01:05am | #5

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   Thanks for all the info. Yes this is a load bearing wall. The rafters run perpendicular to this wall. The bottom of the header is approximatly 20 inches from the cealing. I was hoping to bring this up at least 6 to 8 inches. the existing door ways are 9 feet accros. The windows themselves are 96x48. If I start them 20 inches from the cealing they start pratically at floor level. My thinking was replace the one long header with two. Ad center supports between the two new windows. ?????

3. 
   Guest_ | Apr 02, 1999 01:54am | #6

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   OK Rob,

   Now that I know a little more about the job, I will make the following suggestions.

   Place a temporary support under the roof trusses.

   Cut out the header, at the main doorway in question, alltogether.

   Replace with a double 2X10 header, install jacks on both sides with the center posts as you indicated and all is well. (You could probably get away with 2x8s but why would you want to skimp at this point.)

   48" spans are certainly not a problem. But because of the load on the trusses, it's best to use good headers. Ya never know!!!!!

1. 
   Guest_ | Apr 02, 1999 02:32am | #7

   *Gabe, As long as he left 9.5" of header, couldnt he just cut out some of the existing header in place? Seems easier and cheaper than removing the existing header and replacing it.Just wondering. JonC

1. 
   Guest_ | Apr 02, 1999 03:18am | #8

   *Jon C.In the original post, he had indicated that the header height, for whatever reason, was 16".I don't think,(I may be wrong of course)that the actual header would be a 16" high wood beam. That would be one hell of a beam without a useful purpose. A lot of the time, builders added solid blocking to the inside of garage doors to attach the door openning mechanism to.If it were, then I couldn't see why you couldn't cut out what you didn't need in height and put in a post.Sure would be neat to have a look, for the hell of it.

1. 
   Guest_ | Apr 02, 1999 06:33am | #9

   *If you have a 16" deep header with double top plates you can gain 3" just by removing the top plates. As I said above you can reduce the depth of the header considerably.Ripping a 4x header 20' long in place sounds like a lot more work than removing and replacing it.Don't try to use doubled 2x lumber to replace a 4x.Gabe,If you think that a 16" deep header for a 20' span serves no useful purpose then think again.

1. 
   Guest_ | Apr 02, 1999 07:22am | #10

   *Mike, I know I've probably worked alone too much, which is why I enjoy this forum, but I just cant see how carving out 48+" rough openings in place is harder than removing a weight bearing 20' 4x16. I mean, a pass on each side with a circular saw, drill a starter hole and attack with a sawzall, or my personal weapon of choice for this, a chainsaw with a ripping chain. No temp bracing, no muscling around really big , heavy chunks of wood. Seems quick and easy for a guy working alone even with just basic tools. I feel like I'm missing something here. Hoping to learn something, JonC

2. 
   Guest_ | Apr 02, 1999 07:56am | #11

   *Gabe,I don't think the span is the 48". I think it is the 96".Rob,Please clarify. Is the window 4 feet high and eight feet wide, or 8 feet wide and 4 feet wide?Rich Beckman

3. 
   Guest_ | Apr 02, 1999 08:10am | #12

   *Rich, Scroll up to Rob's last message.

4. 
   Guest_ | Apr 02, 1999 04:43pm | #13

   *Morning Mike,I think we're all missing something here.None of us know what the existing header is made of.Is it a paralam, microlam, laminate, composite, steel, 2x (2x?), 4" x 16" wood beam, OWJ etc?Mike, you're right about the span in my presumption, for some reason I was still thinking that the two garage door opennings were divided with a post, although that's still not clear. He indicated that the windows would extend from the header to nearly touch the floor, which leads me to beleive that the width is 48" for each window, somehow 2 48" windows is less than the space of 1 standard 9'0" garage door. It would really help to know the intended spacing in this case. windows side by side, opposite ends with a framed wall between etc. Ya know what I mean?

5. 
   Guest_ | Apr 03, 1999 08:44am | #14

   *Jon,I assume you are referring to Rob's post #5. Apparantly that post is still unclear. I read it to mean that the windows are eight feet wide. Gabe clearly reads it to mean the windows are four feet wide. I do not presume to think that I read it correctly, but I do think that, given the differing readings, it is possible that it is unclear.Rich Beckman

6. 
   Guest_ | Apr 03, 1999 09:21am | #15

   *Rich,When he said that if he started them 20" from the ceiling they would go almost all the way to the floor, I took that to mean that they were 8' tall. Perhaps that is a mistaken assumption on my part.JonC

7. 
   Guest_ | Apr 03, 1999 10:40am | #16

   *Jon-I'm with you. I'd use a skill saw from each side for the horizontal cut and make the vertical cuts with a sawsall (probably the only indespensible tool in my truck) from the bottom.

8. 
   Guest_ | Apr 03, 1999 09:59pm | #17

   *Jon,And you may well be right!! But I read that as 20" from the ceiling plus the four foot window would put the bottom of the window closer than three or four feet to the floor (assuming an eight to nine foot ceiling). I would think the 20" plus eight feet means the bottom of the window is in the ground!Rob,Please help me clear up my confusion. Which is it?Rich Beckman

9. 
   Guest_ | Apr 03, 1999 10:35pm | #18

   *Jon,You be my man, dude. I would use a chainsaw for trim work if you all wouldn't ban me from Breaktime...Near the stream,J

4. 
   Rob_Scott | Apr 05, 1999 06:24pm | #19

   *
   First off thank you for all the interest and advice. Let me try to Clear a couple of things up
   1. The new windows are 8 feet wide by 5 feet tall.
   2. The existing header is 4 inches thick x 16 inches tall and 20 feet long.
   3. The header is a Solid wood product. I don't know what type.
   4. This is a load bearing wall. The header also supports the existing garage doors.
   5. The garage doors will be removed.
   6. The header has 4 inch cripple studs above them.
   7. There is a 4x4 post at the center point.
   8. In order to insulate the concrete slab I need to put in a raised sub floor. This will proably be about 10 inches in height.
   9. Starting at nine foot cealing to slab height, removing 20 at the top for the existing header and 10 at the bottom and you see my problem.

   I hope this is enough information

   Rob

5. 
   Guest_ | Apr 05, 1999 06:49pm | #20

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   Without going through the mental gymnastics myself of determining how much beam would be left I will say that as long as you leave 7.5" of beam you can span a 96" opening no sweat.

   er...as long as there is no second story or tile roof above it. (maybe even then, but I wouldn't be as sure)

1. 
   Guest_ | Apr 05, 1999 06:50pm | #21

   *Good Morning Rob,Thank you for the information. I guess most of us were out in left field.Instead of raising the water, let me suggest that you lower the bridge.There is no need to spend that kind of money to both raise the floor and change the header size or structural integrity.a) You could install a radiant floor.b) you could install a cork floor (or other insulated flooring)c) you could insulate the floor with high density SM, glue together t&g plywood sheating over top and carpet or whatever after.None of these would add more than 5/8" to 3", depending on which method you use.This way you do save all the structural work and headaches.Good Luck.

6. 
   Rob_Scott | Apr 05, 1999 07:18pm | #22

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   I am in the Seattle area and local code is r-19 for the floor over slab. I was going to extend my existing under floor heat ducting to this room.

1. 
   Rob_Scott | Apr 05, 1999 08:06pm | #23

   *Nope no second story or tile roof. How did you come up with the 7.5 ??? Please enlighten me.

7. 
   Guest_ | Apr 05, 1999 08:23pm | #24

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   Since most of the heat is lost around the edges, you only need to insulate the first two or three feet in from the perimeter. If local code will allow. I would use foam insulation since you would need less than 4 inches.

1. 
   Guest_ | Apr 05, 1999 08:24pm | #25

   *I too live/work in Puget Sound area and we have been using 4x8s to frame 8ft openings at least since 1977 when I got here. It will work, just be carefull not to "overcut" your vertical cuts (or plan on putting trimmers in and cut your beam 99")Glad the rain finally stopped, that was a rough one. Think Griffy will hit 70?

1. 
   Guest_ | Apr 05, 1999 08:32pm | #26

   *Rob, no guestamette can be accuratte without thouroughly understanding the loads that are imposed on this 16" manufactured beam.You say it is a bearing load, and that there is no second story over. I would then suspect that the roof system includes a cancentrated bearing point that lands midspan. Or, the openong was simply overbuilt, otherwise, a couple of 11 1/2" microlams would have been sufficient.If there is some type of midspan bearing, a 7 1/2" header may be insufficient. Carefully check to see what loads are being imposed, and then make sure your header is sized properly. This is nothing more than common sense!One other detail. The load is being transferred to the foundation at the existing posts. The new header will have a new post location. Make sure the new location has an apropriate foundation/pad.It probably will be ok, but if you are built on a grade beam, or framed on posts, you may need to add something at your foundation.Blue

8. 
   Rob_Scott | Apr 05, 1999 08:40pm | #27

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   The 4 x 8 sounds good to me. Im not sure if the local permit guy is going to want engeneering to support the structural change. As for 70 I think it all depends on what kind of year the guy behind him has (Jay?). If he hits then they have to pitch to Griffy if not, (only??) in the 40s.

1. 
   Rob_Scott | Apr 05, 1999 08:43pm | #28

   *Good point, I had planned to continue my existing stub wall across the bottom of the opening. The current is 6 inch tall 6 inch wide.

9. 
   Rob_Scott | Apr 06, 1999 12:41am | #29

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   I am converting my 30*24 garage into a family room. The two garage doors share a header that measures 4*16*20 with no center support. Is it possible to install a center support and lessen the size of the header? I need the additional inches for large windows that will take the place of the doors. Thanks for any info

10. 
    Guest_ | Apr 06, 1999 12:41am | #30

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    Blue-you're right, the thought never crossed my mind that the slab edge might not carry the new load. Sorry Rob. My bad.