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

[MotorSeven]

Any tricks on cutting the birds mouth, I mess them up every time.

The trick I saw them do on my house in '83 was a rafter length template...I think it was a 22' long 1x6 and it had a movable section of plywood at the top to set the ridge angle, and another movable section that goes over the wall to set the birds mouth. Once the first section of ridge was up, they put the template up there and adjusted the plates. They then slid it down the ridge on both sides double checking it. Once they had the angles locked down where they wanted them, they simply placed the template on the rafter laying on the ground and transferred the marks. Quick work with a chainsaw had all the rafters ready in no time.

'83 was a long long time ago.....so foggy memory could be an issue



So, I googled my fingers off ref the roof insulation and I have read that a vertical airspace is recommended to allow the hot air to travel up to the vented peak taking any moisture with it. My current design only had horizontal airspace. Should I add vertical 1x6's over the foam board from eave to peak, then grid over them with the horizontal purlins? Since I am using metal which will allow air flow over the purlin in the ribs of the metal will I really need the vertical strips of wood?

Other methods are similar to what I have in mind & some even have zero dead air space....decking, tar paper, foam board then OSB, then shingle or metal. It is confusing, with recommendations for and against airspace:confused2:

On top of that, some think tar paper is bad and thing the new breathable house wrap stuff should be used instead. I gotta say, tar paper has been around a long time and it works.

 

[lamarbur]

Years ago when we were really interested in log homes, I bought several tapes from the "Hometime show". They built two Maple Island log homes. Both, they turned 1 X 6's vertical, screwed them to the roof, then laid two sets of two inch styrofoam insulation board which left a one inch gap for air movement,, On this they put the usual plywood, then finished off with shingles.

 

[tony Cecil]

Again, my house was built forty years ago....The cross beams, wind beams, and the three inch by six inch V tong and groove are totally exposed up to the peak of the ceiling-roof-..

As I really just found out about the small V going all the way to the exposed outside, if you did your roof the same way, you too would have this very small air space.....A fine `mountaineer`built this cabin the old fashioned way....There is the rest of the underlayment as I previously described, and as I really was involved with the replacement of the roof---ever day--I know it is slightly overdone, as I wanted it to really last, I don`t think you should have any moisture problem, as I haven`t.....I too was reading the same stuff you are, and worried alot about it..

The old roof that I took off was more the way you describe what you are thinking of doing, except it had `special` Canadian cedar shakes---the rough kind---that came from the best part of the log...It lasted way longer than the sawn type....When it was being removed, it had the nailer made out of `heart` pine....It was affixed with three inch long galvanised nails, and it took a crew about three weeks just remove them....There was a very heavy gauge of tar paper, the two by four spacer, with the `tough` type of strofoam(sp) then the nailer(heart pine` and again very heavy tarpaper strips under each layer of shingle.....The tarpaper was fine ad it had been there from the beginning......Now I used the sort of plastic tar with a bunch of rough sandy stuff stuck to it for traction `Grace` , on top of the vantec...
I wouldn`t think it would make any difference if you used a good exterior grade of plywood, and further if you were to use vantec, it is really heavy in the five eights thickness...really heavy imo....vantec has a machined sort of tong and groove that doesn`t let you nail it tooo close to each sheet...Another thing to be careful of ....And one more thing we glued and nailed the vantec to the spacers.....Of course after a good many of the sheets were already up I got concerned about the sapacing...Luckily the product already had that done...Whew...and further with the tarpaper, don`t let it try to bridge any decent sized crack between sheets, as for some reason it will break there pre-maturely.....Tony

 

[MotorSeven]

I got the 5x10x14' ridge supports up today. I used a set of pulleys I bought at an auction for $7 ea. One is a double pulley, the other a single...both look like old cast barn pulleys.
I have borrowed about 1/3 of the scaffolding that I need...still working on the rest.

Here are the pulleys:

I hooked one to the top of the scaffold and the other to a lift strap on the ridge support beam. I did learn that scaffolding likes to separate when used as a hoisting tower....had to pin all the sections together with 8" log screws.


I learned that the rafter layout can be done on the interior floor. Find center on all 4 walls, then pop lines. Once you know your pitch and ridge pole length, measure up from the center line(in the direction of a gable end) and mark that on the floor. Add the thickness of the ridge rafter, then measure back to the wall the length of the rafter. Where it falls on the wall is where it birds mouth sits. Mine fell on the large french door opening, so I could see the necessary angles needed for the birds mouth. I must have made a mistake on the length of the ridge pole because I figured it for a 11/12 pitch, but when it was layed out on the floor it was closer to a 10/12.............so a 10/12 it will be. I was able to lay the template down and have it stick out of the doorway so I could see the actual total length of the rafter.

This must all sound confusing, but it really worked like a charm. I marked the template plywood "plates" and cut the rafter/ridge beam angle, then marked and cut the birds mouth in the other section of plywood. I then built up 4 bucks of scaffold and put the template on the wall on all 4 corners of the house...it fit

 

[MotorSeven]

The layout of the top of the rafter on the floor & the template:

The birds mouth layout as it will be over the wall"

Overall pic of the template then the floor layout method:

 

[MotorSeven]

I hope the pic's help explain the layout method...it is a really cool tool.

The other gable ridge support is up:

I ran three screws through the tail into the wall to stabilize the ridge support. I will add some lateral stabilizer boards before the ridge gets placed on top of it...don't want anything to fall:

Tomorrow I transfer all the rafters from the stickered stack to my trailer for transport up to the house site. I will template and cut them all as I move them so they will be ready to go up on Friday. I will also cut the ridge beam splice so the two sections can be put up separably then mated(44' total length)

I am feeling a little better today about all this....so far so good{knock on Hemlock}

 

[MotorSeven]

Thanks Tony, that helps.... I think I will stick to my original design. 2x6 decking, 30 weight tar paper, 3" beaded Styrofoam, horizontal 1x6 purlins, Tin. I hope it will outlast me......

I bought 45 - 3/8ths inch x 12" structural self tapping wood screws to attach the rafters to the wall and ridge beam. I didn't think my 1/4"x10" log screws that I used to screw down the logs had enough shear strength. these thing use T-40 Torx bit and are very beefy...the price was beefy too...$2.70 ea..........ouch.

 

[MotorSeven]

I spent 8 solid hrs cutting out the rafters and loading them on my trailer. My driveway up to the house has 2 moderate to steep inclines. I made it up the first one spinning most of the way(4WD Low), but on the second incline all 4 tires were spinning & I came to a stop. Best estimate is about 10k lbs on the trailer, with most of the weight back off the hitch. I locked the brake, put it in park, jammed a big rock under the trailer tire and walked down the driveway to my neighbors. He gave me a ride down to my tractor where I grabbed a 30' tow strap, then squeaked by the truck in the ditch. We hooked up the tow strap and pulled the truck/trailer up the hill. I was very lucky it did not pull me backwards down the hill.

Anyway, they are on site ready for the Crane. I am picking up 8 more bucks of scaffold in the AM.

First rafter layout:

Birds Mouth:

Sasquatch Saw:

 

[MotorSeven]

Loaded:

Ridge rafter joint:

 

[MotorSeven]

I think I killed the Sasquatch Saw on the last cut....sounds like the brushes went South. I am pretty much done with it so I am glad it lasted this long. It is a back breaker, and the guard really gets in the way on every cut(so I locked it open). But...it did give me nice square cuts.