How to seal the joints from air leaks???

[Builder-Bob]

What would you folks recommend to seal the timber joints that will be exposed to both outside elements and the interior (joints along outside walls)?  Seems like air leaks/drafts caused by timber shrinkage over time would be a problem. I certainly don't want to have caulking visible, either inside or outside.  I want to solve potential air leaks during construction...not after construction.

I understand "perfect" joints...but even these will shrink.

Thanks for all suggestions.

Bob

[Rooster]

Can you give us an example of an area or joint/wall configuration that you might be concerned about..any photos or drawings?

We're here to help!.......right guys?   

Rooster

[Jay C. White Cloud]

Ditto what Rooster said... ???  Most of the time you have some type of thermal brake, but in a few cases you may have a through tenon, or pass through beam.  Then I would just use an expansion foam from the outside before finishing the frame.

Regards,  jay

[Builder-Bob]

Maybe I'm on the wrong track concept/design wise...I would like to have the timber frame visible on both exterior and the interior...2x4 studs between the bents and plates.  Rather than covering the whole exterior with sheeting.

By air leaks at joints...I was refering to say...the joints of the top and bottom plates (or girts) between each bent.  The joint would be visible on both the exterior and interior.

Bob

[jueston]

I know at least one builder who wanted the frame exposed inside nd out. He routed a grove into all the posts and beams about a half inch deep he then slid the SIPs into these grooves. as the posts shrink, there will still be a visible gap between the exterior finish material and the beam, but it will be very small. As long as the groove is very tight, and sealed with foam, the shrinkage will bot introduce air leakage. But I didn't do this, i just read about it.

That being said, this method limits the amount of insulation because the thickness of the wall is limited by the posts.

[S.Hyland]

Builder Bob,
   I have been interested in what you are talking about. I am working on a W. Oak frame right now that will be exposed on the inside and the outside, with insulated walls grooved into the timbers. There is a thread on the Timber Framers Guild Forum, which deals with a lot of this.
   I used 10x10 posts, which can allow for a pretty good amount of insulation while still allowing the frame to stand proud about 1 1/4" on either side.
   I think that the main thing concerning the joint between insulated wall and timber frame is to allow it to move and still stay sealed. I'm using a foam gasket in the groove with a high compression recovery. It can squish and bounce back repeatedly. I'm hoping that this will allow the frame to move seasonally without breaking the seal.
  If you were to use spray foam or something similar to seal it, as soon as the wood began to shrink it would break the seal permanently.
  All this being said, I should stress that I have not actually seen how this will perform long term. I plan on making some test bents soon with some variations to really see what works best.

[Builder-Bob]

Builder Bob,
   I have been interested in what you are talking about. I am working on a W. Oak frame right now that will be exposed on the inside and the outside, with insulated walls grooved into the timbers. There is a thread on the Timber Framers Guild Forum, which deals with a lot of this.
   I used 10x10 posts, which can allow for a pretty good amount of insulation while still allowing the frame to stand proud about 1 1/4" on either side.
   I think that the main thing concerning the joint between insulated wall and timber frame is to allow it to move and still stay sealed. I'm using a foam gasket in the groove with a high compression recovery. It can squish and bounce back repeatedly. I'm hoping that this will allow the frame to move seasonally without breaking the seal.
  If you were to use spray foam or something similar to seal it, as soon as the wood began to shrink it would break the seal permanently.
  All this being said, I should stress that I have not actually seen how this will perform long term. I plan on making some test bents soon with some variations to really see what works best.

Thanks for the reply...sounds like your solution just might work.  What kind of foam strips are you thinking about using?  Brand? Is the foam in strips/rolls??

I'll try to find the threads in the TF forum.  Thanks again.

Bob

[Jay C. White Cloud]

Hi Builder-Bob,

I just got off the phone discussing this with Sean, (SHyland,) what you want to do, is how it was done, (still is in some area,) for thousands of years.  Most traditional timber frames that are for domestic use are "infill," timber frames.  Now what we need to do, or get from you, is a  design we can start playing with. 

Do you have a design?

Do you use Google Sketchup?

Do you have a site plan where the structure will go?

Once we can see a design our conversation can be less nebulous and move into some tangible solution for your chosen infill method.  We can also discuss any short comings/flaws in the process and how to address them, or consider other options.

Regards,  jay

[Builder-Bob]

Thanks guys...I have been trying to learn sketchup, but I am technology challenged!!! I have a long way to go learning sketchup before I can post any thing descriptive.

My design is a pretty simple floor plan. I like the idea of having the timbers (6" x 8") exposed on both the exterior and interior with infill with 2x6s on the 8" side of the beam, which should net about an inch of beam exposed inside and outside after sheeting. Since the joints on the outside walls will be visible/exposed to the elements of weather/wind/cold etc...I don't want to use caulking that will be visible on either the outside or interior.  I am trying to figure out how to seal the joint to prevent air leaks/cold drafts coming into the house.  I'm thinking it will need to be an expandable foam material that will expand when the joints shrink...but not be visible.

The timbers will probably come from Home Depot, rough sawn Doug Fir.
They will probably be air dryed to come extend, but more green than dry.

I could route grooves on the two facings of beam at the joints, fill with some kind of foam sheet/strip.  I thought about some caulk that would stay flexible and lay a bead aroung the end the beam close to the 4 edges. I thought about a sheet of 1/4" foam the size of the end of the beam (girt to bent) that would compress with the joint and hopefully expand back to fill any beam shrinkage.

We get a certain amount of wind and snow (not so much rain) here in Southern Oregon, the elevation is 5,000 feet. 

I also thought about wrapping the exterior with sheeting and then overlaying the sheeting with 2x6 rough sawn lumber to simulate the beams being exposed, then I wouldn't have to worry about the joints leaking air. This would be quicker than trying to carefully seal each joint on the outside walls.

Thanks for all imput.

Bob

[Builder-Bob]

Builder Bob,
   I have been interested in what you are talking about. I am working on a W. Oak frame right now that will be exposed on the inside and the outside, with insulated walls grooved into the timbers. There is a thread on the Timber Framers Guild Forum, which deals with a lot of this.
   I used 10x10 posts, which can allow for a pretty good amount of insulation while still allowing the frame to stand proud about 1 1/4" on either side.
   I think that the main thing concerning the joint between insulated wall and timber frame is to allow it to move and still stay sealed. I'm using a foam gasket in the groove with a high compression recovery. It can squish and bounce back repeatedly. I'm hoping that this will allow the frame to move seasonally without breaking the seal.
  If you were to use spray foam or something similar to seal it, as soon as the wood began to shrink it would break the seal permanently.
  All this being said, I should stress that I have not actually seen how this will perform long term. I plan on making some test bents soon with some variations to really see what works best.

I didn't have any luck finding infor on the TFGuild site about this subject.

If you have a link, please post it. Thanks.

[S.Hyland]

http://forums.tfguild.net/ubbthreads.php?ubb=showthreaded&Number=25255#Post25255
I apologize for not posting that sooner. Good luck!

[Builder-Bob]

Interesting read....thanks for the link.

[witterbound]

IMO, you would be miles ahead in the long run if you enclose your frame, like the vast majority of timber frames are these days, then add 1 inch trim boards on the outside to look like the frame shows out there.  Having the exposed frame just creates too many places to caulk and waterproof to keep from rotting.....

[Jay C. White Cloud]

IMO, you would be miles ahead in the long run if you enclose your frame, like the vast majority of timber frames are these days, then add 1 inch trim boards on the outside to look like the frame shows out there.  Having the exposed frame just creates too many places to caulk and waterproof to keep from rotting.....

Hello Witterbound,

I don't mean to sound overly challenging to your position but I would like to support BuilderBob in his endeavors with this project.  I concur that you can achieve thermal exclusion more effectively with "overlay," methods when dealing with timber frames, but not easier.  I would also add, through the history of timber framing, infill methods have been, (still are in the majority of places,)  the method of choice.  If you take most timber frames built today and include the fenestration they have in the walls it would not be much different than the thermal bridging you get in an exposed frame.  Reduce the windows by a small factor and you probably come close to breaking even within the thermal dynamics of the frame.  Infill timber framing is much easier than most overlay methods, and gasketing the frame against drafts is more than achievable with a myriad of ways.  I have had this discussion a number of times and one factor that seems to be overlooked but facilitates understanding about timber frame infills, is the consideration of log architecture.  Logs structure don't have the same R factor as most walls, yet when well built are just as efficient, and in some cases more so.  They simply just have more thermal mass than your average home, there by making them much better at storing heat.

Regards, 

Jay

P.S.  B.B. still waiting for a Sketchup drawing ;)

[S.Hyland]

On an entirely non-technical note... I really find the aesthetic of exposing the frame inside and out very attractive. Something that could not really be replicated by applying trim boards after the fact. I don't exactly know to convey it, but there is some thing about infill and exposed timbers both sides that seems very right and whole to me.
Something about the way it's all  so integrated perhaps. I really think the technical problems are quite solvable with the right attention to detail, without any excessive amount of effort.

[Jasperfield]

Builder-Bob,

I built my TF shop and left the frame (including braces) exposed. The reveal was 1.25" inside and out. All joinery was centered, including braces.

For infill, I ripped 2X4s to 3" and framed inside the "panel" sections. PS2000 double-sided, foil covered, foam insulation was installed between the 3" framing. Then, the inside and outside of the frame was covered with 1/4" plywood, tyvek, and then tarpaper (which overlapped just a bit for draft proofing). This was then covered with vertical shiplap pine which had the tongue trimmed back to give a 1/16th joint.

After the siding was applied the excess tarpaper was trimmed flush with its adjacent surface, thereby "disappearing". I have no drafts.

While determining a method to eliminate drafts, I reviewed many methods and materials. Most were too tedious, complex, high-tech & expensive, temperature sensitive, movement sensitive, interfered with joints, or just unproven and too costly.

This worked very well for me. Maybe you can use it, too.

[Jay C. White Cloud]

S. Hyland, you hit the nail on the head. You can spot a faux timber frame facade on a house a mile away.  The difference between the real thing is extreme.  I love building them this way when ever I get a chance.

[witterbound]

Where do you guys live where you see faux timber frames on the outside?  I guess I've seen some faux timber frame porches, as well as trim on the inside that is supposed to look like timberframe or posts and beam, but I don't recall seeing "siding" where someone wanted the outside to look a like a timberframe. 

[Jay C. White Cloud]

Hi Witterbound,

Go through most urban neighborhoods and just about any circa 1920 to 1940 faux Tudor, Craftsman, some Dutch Revival, just to name a few, will have some timber faux work.  There is a fine example on the campus of Dartmouth college and several at Harvard and Yale.  The better ones will use 50 mm to 75 mm slabs for the work (~2" to 3")

Here is a quote from "A Field Guide to Amercan Houses," by McAlester:

decorative half-timbering present on about half of the examples.

Regards,

jay

[Builder-Bob]

Builder-Bob,

I built my TF shop and left the frame (including braces) exposed. The reveal was 1.25" inside and out. All joinery was centered, including braces.

For infill, I ripped 2X4s to 3" and framed inside the "panel" sections. PS2000 double-sided, foil covered, foam insulation was installed between the 3" framing. Then, the inside and outside of the frame was covered with 1/4" plywood, tyvek, and then tarpaper (which overlapped just a bit for draft proofing). This was then covered with vertical shiplap pine which had the tongue trimmed back to give a 1/16th joint.

After the siding was applied the excess tarpaper was trimmed flush with its adjacent surface, thereby "disappearing". I have no drafts.

While determining a method to eliminate drafts, I reviewed many methods and materials. Most were too tedious, complex, high-tech & expensive, temperature sensitive, movement sensitive, interfered with joints, or just unproven and too costly.

This worked very well for me. Maybe you can use it, too.

This sounds like what I would like to acheive...thanks...could you post a couple pix maybe an interior corner detail and exterior???  I would appreciate it!!

[Builder-Bob]

Thanks..Jay C. for the private email!!!!

Bob

[witterbound]

Not much of the faux timberframe down here in the hills of arkansas.  Sounds like that's a good thing.  Good luck with your project.  Post pics when you're done.

[Builder-Bob]

After much thought and consideration of the pros/cons of building my house with the timbers exposed on both the interior and exterior...I think I will go with a tradition TF with the exterior wrapped with sheeting and then overlay some rough sawn 2x6 where the beams would be to resemble timbers.

This project is still in the design stage and probably won't start construction until spring of next year. I'm trying to do cash as I go so as not to have a mortgage.  It will definately be a work in progress over time.  My goal is to get it dried in and then live in it as I detail and finish it.

Thanks to all for your imput.

Bob

[Jay C. White Cloud]

Hey Builder-Bob,

I hope you felt supported in your desire to build with the infill method, and didn't get discouraged from some of the feedback.

I think I will go with a tradition TF with the exterior wrapped with sheeting...

By no mean is this the traditional method...infill is the traditional method.  You can still achieve your goal in this.  I will state that wiring, plumbing and mechanicals are more of a challenge with an infill method, but no more so than with the exterior encapsulation methods.  It isn't until you create an enlarge thermal envelope with wall trusses that mechanicals become easier.  So infill or wrap, the wiring, plumbing and mechanicals will be the same challenge, just different solutions.

Regards,

jay

[Rooster]

Bob,

It's nice that your time-frame for having this built is more than a year out...this will give you plenty of time to work out the details without trying to rush it.

...I think I will go with a tradition TF with the exterior wrapped with sheeting and then overlay some rough sawn 2x6 where the beams would be to resemble timbers.

Bob

I would try and talk you out of overlaying any horizontal or even diagonal trim boards on the outside of the exterior siding.  As the rain hits the exterior walls, and runs down the siding it will start to collect on the top surface of the trim board and eventually get behind the trim board causing large amounts of moisture to be trapped, causing the trim and the siding to eventually rot.  Caulking these long runs will help initially, but with expansion, contraction and warping of the trim board the caulk will fail.  It will be a never ending maintenance problem, and hard to keep up with especially farther up the walls.  If I had a nickel for every window frame, window jamb, door jamb, "dutch style" door with the cross-buck trim on the outside, that I have had to replace completely because of the water that got behind the unneccessary and usually "decorative" trim...well, you get the  picture. 

Think of the siding as a smooth skin of the building...designed to shed a lot of water and keep it away from the frame...any place where the water can "hold-up" can potentially cause rot.

Sorry to rain on your parade, (pun intended) but I don't want to see you have to do extra work down the road, or have to pay someone like me to fix it when you decide many years from now that you no longer want to climb ladders... ;)

Peace,

Rooster