The Log house Project begins........

[tnmike]

Cut an oak beam or make a laminated oak beam to span the top log? Whatever you do I would make sure that the vertical beams on either side of the window carry the load. The article below is a really good one to refer to. It lists woods by species as to the strength in tension, deflection, shearing etc. Wood can be very strong especially in engineered beams, trusses and rafters. Cedar is a softwood and is pretty good under compression but poor under deflection.( especially compared to oak)

http://www.fpl.fs.fed.us/documnts/pdf1994/winan94a.pdf

You want to calculate beam deflection? The calculators in the link below will do it for you. Steel has no substitute under deflection loading. In your case steel would have been great just above the window opening. Not easily doable now so the top log is the next best bet. With the poor deflection properties of cedar I would want to make sure that ten foot span is not heavily loaded. Your glass will love you for it.

http://www.engineersedge.com/beam-deflection-menu.htm

Even though there is no deflection now, what happens when there is a foot or more of snow load on the roof? As I have said before I am a spectator throwing out suggestions that may help.

 

[boxygen]

You absolutely do not need any post underneath a ridge on a gable end of a regular gable roof. If the rafters are properly secured to the top of walls and your collar ties are all in place, then the ridge does absolutely nothing except aid in the installation of the rafters. You have some very beefy rafters and I would guess these still have a pretty good amount of moisture in them. As the timbers dry out they will naturally deflect a little, the timbers will shrink and the ridge height will lower slightly with all these little changes. By installing a post under the end of the ridge, as these little changes were happening the height of the ridge was unable to go down therefore putting more weight on the post deflecting the logs over the opening above. You can do virtually any window configuration you would like on the gable end and you dont need to add any structure to it. In fact you need to remove the post under the ridge, it is what is causing the problems. The only structural concern that needs to be thought about is adding some shear strength to the gable wall to resist wind loading. In reality, that is probably negligible with the size of all the timbers you have used. That building isnt going anywhere. The only time a post under the ridge is necessary is when you have a vaulted ceiling with no collar ties. In that case the ridge is sized like a beam to hold the weight of the rafters so the exterior walls dont bow out.
No offense to the other responses but these guys were just guessing. This is exactly what an engineer would tell you. I know its hard to believe one person over another in an internet forum. Here is an article that I found very quickly on Google to back this up. Structural Support - Structural Ridge Beam - Belmar, NJ
Goodluck. Progress looks great.:thumbsup:

 

[MotorSeven]

Thanks Box, yes I do understand that a the rafters/ridge beam are capable of supporting the roof without ridge posts. I did not know about the settling, but it makes sense and as it is right now, it can only settle so far, then it is done. I think using all three -Collar Ties, Tie poles and the Ridge Post make it all stronger? Each backs the other up, all are subject to fail if improperly spaced/attached.
Once I put in the Crows foot bracing my problem was solved, so I am not too concerned about further movement. I think we have sidetracked a little here, at this point I don't perceive a problem with the structure as it is. These questions of load came about when we discussed removing the ridge support and bracing....I am not removing it, just going to work it all into the window scheme.

 

[boxygen]

Motor,
Do as you would like, after all its your house so whatever makes you sleep at night is important. I saw that you were designing around the ridge post and braces and I thought it was silly because not only is it NOT making it stronger, it is creating a problem, not solving one. From what I am gathering you were taking two extra steps (designing a window around post and adding a beam to stop deflection at the door below)to solve a problem that was created by doing something unecessary.
I agree with you that there are no problems with the structure, except for the ridge post . In fact the building is definitely overbuilt which isnt a bad thing. I know you were talking about the window design so my structual advise was meant to help the window design. Just so my points are clear.

1. Remove the Ridgepost because it is not making anything stronger, and creating problems for other parts of the building.
2. Add no extra cost or structural members
3. DESIGN ABSOLUTELY ANY WINDOW YOU CAN DREAM UP WITHOUT LIMITATIONS OF A POST AND KNEE BRACES!!!

However, if you LIKE the design of teh post and knee braces and like working that into your design scheme then that is another story. But that is not what I was getting out of the discussion.

I respectfully disagree if you decide to keep the post on gable but salute you and this great country to do whatever you want to do on your own home:thumbsup:

Honestly im not trying to be abrasive and I've tried to present the facts as objectively as possible to help you make an informed decision(not an easy thing to do on the internet). This is what I'm paid very fairly to do everyday. I get very little satisfaction about being "right" but great satisfaction in finding an appropriate solution that makes a better product in the end.
Any builder worth his salt will give you the same advise.
Best,

 

[MotorSeven]

No, no Box, no abrasion felt...not even 4,000 grit:laughing:

We agree on everything except the removal of the post. I see it as a back-up, you say it can cause problems, I disagree and this is why:

-The rafter roof without ridge posts pushes out on the walls(we agree here).
-Collar ties and tie poles are supposed to keep the walls from spreading(again we agree).
-My joe schmoe theory is that the walls cannot spread unless the ridge beam w/rafters attached moves down( I think we also agree)
-If the ridge post pushed down(other than settling) then something else is failing(don't know if you agree here)
-Having all three prevents catastrophic movement(here we disagree)

So my question is, if the collar ties and the tie poles are doing their job, no weight is on the ridge post. If they are not and the ridge post catches this weight, what harm is done? Once the weight is all settled out on the ridge posts(and I have three of them), the three collar ties and the tie poles, it should be done moving. Except for the log walls themselves shrinking/settling and they will, all of these things will settle together(hopefully). If you can explaing this specific harm, I am all ears(don't sand them off with 40 grit)

 

[Iplayfarmer]

I like your chosen window design. I think it meets your requirements of fitting in with the general appearance and style of the building while standing out as different from the average log house.

Good job.

 

[hawkeye08]

I wonder if the initial deflection was caused by the vertical post not shrinking as much as the horizontal walls and thereby causing the extra load that you solved with the crows foot?

It is a bit of fun to think about this, wish I was closer, would enjoy giving you a hand.

 

[boxygen]

No, no Box, no abrasion felt...not even 4,000 grit:laughing:

We agree on everything except the removal of the post. I see it as a back-up, you say it can cause problems, I disagree and this is why:

-The rafter roof without ridge posts pushes out on the walls(we agree here).
-Collar ties and tie poles are supposed to keep the walls from spreading(again we agree).
-My joe schmoe theory is that the walls cannot spread unless the ridge beam w/rafters attached moves down( I think we also agree) Agree-If the ridge post pushed down(other than settling) then something else is failing(don't know if you agree here) Agree-Having all three prevents catastrophic movement(here we disagree)
Yes we disagree here, somewhat. The gable ends where it is posted would have to have a bomb hit them to fail. If you have a collar tie fail the ridge will deflect independent of the gable ends. Yes the ends will pick up some of the load until your window below wont open and then sag in the middle because the ridge is acting like a beam. I dont remember the dimensions of your building or ridge beam but it has to be a very large beam over the length not to deflect (30')
So my question is, if the collar ties and the tie poles are doing their job, no weight is on the ridge post. Yes If teh collar ties are doing their job, there is no stress on the ridge or postIf they are not and the ridge post catches this weight, what harm is done? No harm is done, except you cant design any window you want Once the weight is all settled out on the ridge posts(and I have three of them), Ah ha! I didnt realize you had a post in the middle too! this is good because it takes the span out of the ridge allowing it to act more like a beamthe three collar ties and the tie poles, it should be done moving. Correct it shouldnt move once its dried out. I would trim the post once things have stablized so there is very little weight on it and so it isnt deflecting the opening below. Except for the log walls themselves shrinking/settling and they will, all of these things will settle together(hopefully). Yes everything will shrink somewhat the same however the length of the post wont since it doesnt shrink in that dimensionIf you can explaing this specific harm, I am all ears(don't sand them off with 40 grit)

I think we are starting to understand each other a little better.

Bottom line is you are taking the belt and suspenders approach which is fine as long as the posts have a clear path to the foundation without deflection, which right now they dont at least on one gable end. Since we are trying to keep this on topic of windows, it seems like you could get rid of the suspenders and open your options for windows. Only you can make this value judgment. THe fact that you have noticed defection in your opening below is what made me pipe up. If that was a solid wall below, I never would have said anything. Once the rest of the gable end wall is built, it will make it so ridgid that the triangle between the wall below acting like a collar tie and the rafters will never allow the ridge to move, with or without the post. Are the gable end walls solid logs also?

 

[boxygen]

I wonder if the initial deflection was caused by the vertical post not shrinking as much as the horizontal walls and thereby causing the extra load that you solved with the crows foot?

It is a bit of fun to think about this, wish I was closer, would enjoy giving you a hand.

Yes, there should be no load on that post unless things are shrinking!

 

[EddieWalker]

You absolutely do not need any post underneath a ridge on a gable end of a regular gable roof. If the rafters are properly secured to the top of walls and your collar ties are all in place, then the ridge does absolutely nothing except aid in the installation of the rafters. You have some very beefy rafters and I would guess these still have a pretty good amount of moisture in them. As the timbers dry out they will naturally deflect a little, the timbers will shrink and the ridge height will lower slightly with all these little changes. By installing a post under the end of the ridge, as these little changes were happening the height of the ridge was unable to go down therefore putting more weight on the post deflecting the logs over the opening above. You can do virtually any window configuration you would like on the gable end and you dont need to add any structure to it. In fact you need to remove the post under the ridge, it is what is causing the problems. The only structural concern that needs to be thought about is adding some shear strength to the gable wall to resist wind loading. In reality, that is probably negligible with the size of all the timbers you have used. That building isnt going anywhere. The only time a post under the ridge is necessary is when you have a vaulted ceiling with no collar ties. In that case the ridge is sized like a beam to hold the weight of the rafters so the exterior walls dont bow out.
No offense to the other responses but these guys were just guessing. This is exactly what an engineer would tell you. I know its hard to believe one person over another in an internet forum. Here is an article that I found very quickly on Google to back this up. Structural Support - Structural Ridge Beam - Belmar, NJ
Goodluck. Progress looks great.:thumbsup:

How many collar ties did you see in this house? As one of those guys who are just guessing, and not an "engineer" I'm curious about your advise.

I see two collar ties at the midway point. While fine for the size and design of the structure they in no way look like a truss to me.

Due to the size and span of the roof, removing the ridge post is an important structural part of this rooof to hold the ridge beam in place. Nowhere is there a truss in this building, and the end walls are not continous to hold up the ridge beam.

Removing the ridge beam seems like a very bad idea!!!!!!!!!!!

Are you an engineer? Did you look at the roof design? have you ever built anything?

Eddie