support beams in the attic.

jerfitz5 · Post by **jerfitz5** » Sun Oct 12, 2003 9:25 pm

A new issue in the attic.
The attic has wood beams about 2m over the floor. If I try to build the cut room under these beams I will have really low ceilings. (180cm) Not enough room for drum overheads. If I build over the beams then the beams will cut throught the walls. If I seal off the beams where the go through the walls will I still manage some degree of isolation?

giles117 · Post by **giles117** » Sun Oct 12, 2003 11:04 pm

Yes you will have a some degree of isolation, however, if the beams travel the length of the Live and Control rooms, the vibrations from either room will travel the length of the beam. Are these support beams? Do you have any pics?

Kinda difficult for me to advise without a visual reference.

Bryan Giles

jerfitz5 · Post by **jerfitz5** » Mon Oct 13, 2003 10:40 am

Hi Giles, thanks for the responce.
Yes they are support beams. Here is a picture. My rendering skills are a little limited but maybe you can get the idea.

giles117 · Post by **giles117** » Mon Oct 13, 2003 10:51 am

So all the beams running crosswise are supporting something. I wonder if the same Idea used in basements to relocate jackposts can be done here?

The issue becomes what are they supporting down in the middle. A photo would be cool. If they are not physically touching anything else, perhaps support posts can be place towards the end of these beams to so that they maintain the roof support needed. Then you cut the middle portion out giving you the headroom you seek.

I am guessing.. as this kind of structural work I have never done and I realize roofs have to be designed to support a great amount of weight, especially in snow climates.

I cede the floor.

John, Steve??

Bryan Giles

eric · Post by **eric** » Mon Oct 13, 2003 2:04 pm

When constructing a roof there are two basic methods for supporting the rafters.( the angled sides that the roofing sits on) You need to understand that the concept is to create a triangle with the shape of the roof. The rafters are the two sides with the third side being the bottom chord of the design. Are you with me so far? The botom chord is generally refered to as a collar tie. In other words if I put a bunch of wieght on the peak of the roof ( triangle ) it wont spread out and flatten. This is what the collar tie does, it keeps the triangle from spreading out by holding the rafters together at some point. There are some specific rules to follow which are usually dictated by local codes ,snow loads and things like that as to how far up the triangle the ties can be. Ther are too many variables to give an easy number.
The second method is to use a large beam at the top of the peak. This allows the weight to be put on the beam and stops the downward force from spreading out the roof. you then have no need to use ties as the load is actually on the beam which won't move downward.Are you with me so far?
Simply put if you don't have a large supportive beam running down the peak of the roofline, removing the collar ties, which probably have sheetrock attached to them( the ceiling), would be a really bad idea.
In looking at you drawing I would guess the you have the collar ties in place and that would mean you would want to leave things as are.Hope that helps
Eric

giles117 · Post by **giles117** » Mon Oct 13, 2003 2:14 pm

Thanks for the education Eric. I didn't want to give him bad info. That totally makes sense.

In the last home I remodeled, the roof was designed similar to what you described, (The triangle vibe), except they used the ceiling of the 2nd floor, or floor of the attic however you wanna look at it, to be the collar.

I was able to enjoy full standing height for most of the attic (It was my old office. hot as hell in the summer though)

Had to install a furnace/air-con for the attic and second floor (well not had to, but what the heck it was cheap to do)

Bryan Giles

jerfitz5 · Post by **jerfitz5** » Mon Oct 13, 2003 8:17 pm

Thanks for the informative replies.
This is the situation. The house is 120 years old so I dont want to risk any structural changes at this point plus my wife would never go for it. So that leaves me with the choice of...

1. having a cut room with under 180cm ceilings which I can't imagine is accousticly ideal. I am a towering 5'4". Not an issue for me but my drummer has ape arms and I don't want him scraping the paint off the ceiling.

or

2. building around the beams and having some headroom and being astheticly pleasing (also very important to me) at the risk of traveling vabrations.

Hmmm.

Thanks again for the enlightenment. johnsayersd.com rules,

Jeremy

Post by **John Sayers** » Tue Oct 14, 2003 8:39 am

Eric's correct Jeremy - you'll have to live with the cross beams. I'd drywall up to the peak of the roof and use the whole volume. YOu'll get some sound transfer through the beams but you'll have to live with it - unless you go to the trouble of sealing each beam off individually.

cheers
john

jerfitz5 · Post by **jerfitz5** » Tue Oct 14, 2003 7:08 pm

As I thought. You realize that the 5 cross beams run all the way to the rafters so either way I have to cut around those peckers. As I am writing this e mail my roof guy calls and suggests we get a new roof including all new beams and rafters. $. So I will talk to him about Erics idea of the big post in the center but either way the project goes on hold till spring. Thanks for helping me out and in the words of the governor of the state of California...I'll be back.
Jeremy

frederic · Post by **frederic** » Wed Oct 15, 2003 8:49 am

You have been given excellent information, but let me add another option for you.

2M would be approximately 6 1/2 ', which is rather low.

If you were to double up the stringers, you could move them 1/3 of the way up from where they are now, towards the peak.

This is what I just finished doing, actually, in my garage loft. I moved the stringers up taking the prior 6'1" ceiling to a nice, comfortable 7' high ceiling.

My stringers were nailed in on one side of the joists making the peak, so I cut them down, doubled them up (one on each side of the joists) and used deck screws.

Before I cut anything, I cut down a 1/2" diameter hardwood dowel just short of the height between the peak's main joist, and the floor, and wedged a bathroom scale between the bottom of the dowel and the floor. As I removed stringers, I carefully watched the scale to see if the "weight" changed. If the weight went up, I then know I cut out something structurally important, and could put it back if I had to.

I verified my stringers provided nothing structurally, the scale's indication never changed.

Another "trick" to keeping things from bowing out while you modify the structure, is to put in several screw eyes with a lag-bolt thread in the sides, then run steel cable between them with a turnbuckle in the center. Then you make it tight, and the cables will support the roof through tension.

giles117 · Post by **giles117** » Wed Oct 15, 2003 8:55 am

That is a brilliant Idea Frederic. he'd only have to move 2 of the beams up to provide the height for drums if he wanted to keep the labor to a minimum as well.

Bryan Giles

eric · Post by **eric** » Wed Oct 15, 2003 11:00 am

O.K
In response to Fredericks post "beware". Weight bearings capacities are often calculated based on dead loads. however you also need to calculate things like sheer, which is essentially motion in a structure. Put up the house of cards and see that you can put lots of wieght on it. As soon as the load becomes eccentric to any side however,Boom it loses it's ability to stand. Sometimes it takes a long time for a house to settle after you alter it's base. Structures don't always fail in a catastrophic manner. sometimes things just sag.The first thing you usually notice would be cracks in walls or doors that just don't close like they once did. Of course living in a 100 year old house you may have a little of that already. The fact that a scale says nothing has moved does not mean that it isn't ready to. Many codes are based on snow loads that may occur only once in 100 years.
The best and smartest thing to do is get someone who knows about your local stuff. Building departments can help and lots of guys in the construction business can tell you what to do. Don't mess with a structure unless you know what you are getting into.
Just my own two cents worth.
Eric

frederic · Post by **frederic** » Wed Oct 15, 2003 12:01 pm

In response to Fredericks post "beware".

Fair enough. I had hoped that I presented a fair experience of what I did. I do have the advantage that my house was built in 1941, thus whatever settling it could do, it has done.

little of that already. The fact that a scale says nothing has moved does not mean that it isn't ready to. Many codes are based on snow loads that may occur only once in 100 years.

I would agree, my scale indication only indicates nothing moved not that its ready to move.

However, moving my stringers up a foot, and doubling them up, provides approximately equal strength to the original stringer that was there in the first place, all other things being equal.

Anyway Eric, your comments were good and well thought out. I do hope he acquires professional services to evaluate moving them. But I do believe moving some of the stringer's up won't cause him any grief.

Though, you're all welcomed to call me in 20 years and ask if my garage loft is still there

eric · Post by **eric** » Wed Oct 15, 2003 12:47 pm

To be honest You probably made it stronger.
The old Norwegian carpenter I worked for said you could go 1/3 the way down the rafter and be safe. Nowadays it''s trusses with engineering calculations attached.With the way lawyers work around here if you goof,look out! For all the roofs I have framed up, either stick built or truss, There is always a safety factor built in just in case Santa comes to your house first and has a full load of toys. ( new preamps and compressors?) I have also seen first hand what happens if you remove the wrong stick from the logpile. I certainly am not implying that you have ruined your house by moving a couple of collar ties. Just watch out on Christmas Eve. hahaha
Eric

frederic · Post by **frederic** » Wed Oct 15, 2003 11:33 pm

eric wrote:To be honest You probably made it stronger.
the wrong stick from the logpile. I certainly am not implying that you have ruined your house by moving a couple of collar ties. Just watch out on Christmas Eve. hahaha
Eric

heh-heh.

I think a lot of the strength comes from the way the initial construction was done, on this house. The rafters are 2x16's in most places, 2x12 in other places, made in the day where a 2x16 is really 2" x 16".

I just wish it had the perimeter I and H beams around the corners like the rest of the house. Then I could have put my vehicle lift and my overhead crane in the garage underneath and not worry about the overhead joists (the studio floor) sagging. So, I chose to put the weight on top, rather than underneath.

heh-heh.